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<title>About this Documentation Node.js v0.10.24 Manual &amp; Documentation</title>
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<h1>Node.js v0.10.24 Manual &amp; Documentation</h1>
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<h2>Table of Contents</h2>
<ul>
<li><a href="#all_about_this_documentation">About this Documentation</a><ul>
<li><a href="#all_stability_index">Stability Index</a></li>
<li><a href="#all_json_output">JSON Output</a></li>
</ul>
</li>
<li><a href="#all_synopsis">Synopsis</a></li>
<li><a href="#all_global_objects">Global Objects</a><ul>
<li><a href="#all_global">global</a></li>
<li><a href="#all_process">process</a></li>
<li><a href="#all_console">console</a></li>
<li><a href="#all_class_buffer">Class: Buffer</a></li>
<li><a href="#all_require">require()</a><ul>
<li><a href="#all_require_resolve">require.resolve()</a></li>
<li><a href="#all_require_cache">require.cache</a></li>
<li><a href="#all_require_extensions">require.extensions</a></li>
</ul>
</li>
<li><a href="#all_filename">__filename</a></li>
<li><a href="#all_dirname">__dirname</a></li>
<li><a href="#all_module">module</a></li>
<li><a href="#all_exports">exports</a></li>
<li><a href="#all_settimeout_cb_ms">setTimeout(cb, ms)</a></li>
<li><a href="#all_cleartimeout_t">clearTimeout(t)</a></li>
<li><a href="#all_setinterval_cb_ms">setInterval(cb, ms)</a></li>
<li><a href="#all_clearinterval_t">clearInterval(t)</a></li>
</ul>
</li>
<li><a href="#all_console_1">console</a><ul>
<li><a href="#all_console_log_data">console.log([data], [...])</a></li>
<li><a href="#all_console_info_data">console.info([data], [...])</a></li>
<li><a href="#all_console_error_data">console.error([data], [...])</a></li>
<li><a href="#all_console_warn_data">console.warn([data], [...])</a></li>
<li><a href="#all_console_dir_obj">console.dir(obj)</a></li>
<li><a href="#all_console_time_label">console.time(label)</a></li>
<li><a href="#all_console_timeend_label">console.timeEnd(label)</a></li>
<li><a href="#all_console_trace_label">console.trace(label)</a></li>
<li><a href="#all_console_assert_expression_message">console.assert(expression, [message])</a></li>
</ul>
</li>
<li><a href="#all_timers">Timers</a><ul>
<li><a href="#all_settimeout_callback_delay_arg">setTimeout(callback, delay, [arg], [...])</a></li>
<li><a href="#all_cleartimeout_timeoutid">clearTimeout(timeoutId)</a></li>
<li><a href="#all_setinterval_callback_delay_arg">setInterval(callback, delay, [arg], [...])</a></li>
<li><a href="#all_clearinterval_intervalid">clearInterval(intervalId)</a></li>
<li><a href="#all_unref">unref()</a></li>
<li><a href="#all_ref">ref()</a></li>
<li><a href="#all_setimmediate_callback_arg">setImmediate(callback, [arg], [...])</a></li>
<li><a href="#all_clearimmediate_immediateid">clearImmediate(immediateId)</a></li>
</ul>
</li>
<li><a href="#all_modules">Modules</a><ul>
<li><a href="#all_cycles">Cycles</a></li>
<li><a href="#all_core_modules">Core Modules</a></li>
<li><a href="#all_file_modules">File Modules</a></li>
<li><a href="#all_loading_from_node_modules_folders">Loading from <code>node_modules</code> Folders</a></li>
<li><a href="#all_folders_as_modules">Folders as Modules</a></li>
<li><a href="#all_caching">Caching</a><ul>
<li><a href="#all_module_caching_caveats">Module Caching Caveats</a></li>
</ul>
</li>
<li><a href="#all_the_module_object">The <code>module</code> Object</a><ul>
<li><a href="#all_module_exports">module.exports</a><ul>
<li><a href="#all_exports_alias">exports alias</a></li>
</ul>
</li>
<li><a href="#all_module_require_id">module.require(id)</a></li>
<li><a href="#all_module_id">module.id</a></li>
<li><a href="#all_module_filename">module.filename</a></li>
<li><a href="#all_module_loaded">module.loaded</a></li>
<li><a href="#all_module_parent">module.parent</a></li>
<li><a href="#all_module_children">module.children</a></li>
</ul>
</li>
<li><a href="#all_all_together">All Together...</a></li>
<li><a href="#all_loading_from_the_global_folders">Loading from the global folders</a></li>
<li><a href="#all_accessing_the_main_module">Accessing the main module</a></li>
<li><a href="#all_addenda_package_manager_tips">Addenda: Package Manager Tips</a></li>
</ul>
</li>
<li><a href="#all_addons">Addons</a><ul>
<li><a href="#all_hello_world">Hello world</a></li>
<li><a href="#all_addon_patterns">Addon patterns</a><ul>
<li><a href="#all_function_arguments">Function arguments</a></li>
<li><a href="#all_callbacks">Callbacks</a></li>
<li><a href="#all_object_factory">Object factory</a></li>
<li><a href="#all_function_factory">Function factory</a></li>
<li><a href="#all_wrapping_c_objects">Wrapping C++ objects</a></li>
<li><a href="#all_factory_of_wrapped_objects">Factory of wrapped objects</a></li>
<li><a href="#all_passing_wrapped_objects_around">Passing wrapped objects around</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_process_1">process</a><ul>
<li><a href="#all_event_exit">Event: &#39;exit&#39;</a></li>
<li><a href="#all_event_uncaughtexception">Event: &#39;uncaughtException&#39;</a></li>
<li><a href="#all_signal_events">Signal Events</a></li>
<li><a href="#all_process_stdout">process.stdout</a></li>
<li><a href="#all_process_stderr">process.stderr</a></li>
<li><a href="#all_process_stdin">process.stdin</a></li>
<li><a href="#all_process_argv">process.argv</a></li>
<li><a href="#all_process_execpath">process.execPath</a></li>
<li><a href="#all_process_execargv">process.execArgv</a></li>
<li><a href="#all_process_abort">process.abort()</a></li>
<li><a href="#all_process_chdir_directory">process.chdir(directory)</a></li>
<li><a href="#all_process_cwd">process.cwd()</a></li>
<li><a href="#all_process_env">process.env</a></li>
<li><a href="#all_process_exit_code">process.exit([code])</a></li>
<li><a href="#all_process_getgid">process.getgid()</a></li>
<li><a href="#all_process_setgid_id">process.setgid(id)</a></li>
<li><a href="#all_process_getuid">process.getuid()</a></li>
<li><a href="#all_process_setuid_id">process.setuid(id)</a></li>
<li><a href="#all_process_getgroups">process.getgroups()</a></li>
<li><a href="#all_process_setgroups_groups">process.setgroups(groups)</a></li>
<li><a href="#all_process_initgroups_user_extra_group">process.initgroups(user, extra_group)</a></li>
<li><a href="#all_process_version">process.version</a></li>
<li><a href="#all_process_versions">process.versions</a></li>
<li><a href="#all_process_config">process.config</a></li>
<li><a href="#all_process_kill_pid_signal">process.kill(pid, [signal])</a></li>
<li><a href="#all_process_pid">process.pid</a></li>
<li><a href="#all_process_title">process.title</a></li>
<li><a href="#all_process_arch">process.arch</a></li>
<li><a href="#all_process_platform">process.platform</a></li>
<li><a href="#all_process_memoryusage">process.memoryUsage()</a></li>
<li><a href="#all_process_nexttick_callback">process.nextTick(callback)</a></li>
<li><a href="#all_process_maxtickdepth">process.maxTickDepth</a></li>
<li><a href="#all_process_umask_mask">process.umask([mask])</a></li>
<li><a href="#all_process_uptime">process.uptime()</a></li>
<li><a href="#all_process_hrtime">process.hrtime()</a></li>
</ul>
</li>
<li><a href="#all_util">util</a><ul>
<li><a href="#all_util_format_format">util.format(format, [...])</a></li>
<li><a href="#all_util_debug_string">util.debug(string)</a></li>
<li><a href="#all_util_error">util.error([...])</a></li>
<li><a href="#all_util_puts">util.puts([...])</a></li>
<li><a href="#all_util_print">util.print([...])</a></li>
<li><a href="#all_util_log_string">util.log(string)</a></li>
<li><a href="#all_util_inspect_object_options">util.inspect(object, [options])</a><ul>
<li><a href="#all_customizing_util_inspect_colors">Customizing <code>util.inspect</code> colors</a></li>
</ul>
</li>
<li><a href="#all_util_isarray_object">util.isArray(object)</a></li>
<li><a href="#all_util_isregexp_object">util.isRegExp(object)</a></li>
<li><a href="#all_util_isdate_object">util.isDate(object)</a></li>
<li><a href="#all_util_iserror_object">util.isError(object)</a></li>
<li><a href="#all_util_pump_readablestream_writablestream_callback">util.pump(readableStream, writableStream, [callback])</a></li>
<li><a href="#all_util_inherits_constructor_superconstructor">util.inherits(constructor, superConstructor)</a></li>
</ul>
</li>
<li><a href="#all_events">Events</a><ul>
<li><a href="#all_class_events_eventemitter">Class: events.EventEmitter</a><ul>
<li><a href="#all_emitter_addlistener_event_listener">emitter.addListener(event, listener)</a></li>
<li><a href="#all_emitter_on_event_listener">emitter.on(event, listener)</a></li>
<li><a href="#all_emitter_once_event_listener">emitter.once(event, listener)</a></li>
<li><a href="#all_emitter_removelistener_event_listener">emitter.removeListener(event, listener)</a></li>
<li><a href="#all_emitter_removealllisteners_event">emitter.removeAllListeners([event])</a></li>
<li><a href="#all_emitter_setmaxlisteners_n">emitter.setMaxListeners(n)</a></li>
<li><a href="#all_emitter_listeners_event">emitter.listeners(event)</a></li>
<li><a href="#all_emitter_emit_event_arg1_arg2">emitter.emit(event, [arg1], [arg2], [...])</a></li>
<li><a href="#all_class_method_eventemitter_listenercount_emitter_event">Class Method: EventEmitter.listenerCount(emitter, event)</a></li>
<li><a href="#all_event_newlistener">Event: &#39;newListener&#39;</a></li>
<li><a href="#all_event_removelistener">Event: &#39;removeListener&#39;</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_domain">Domain</a><ul>
<li><a href="#all_warning_don_t_ignore_errors">Warning: Don&#39;t Ignore Errors!</a></li>
<li><a href="#all_additions_to_error_objects">Additions to Error objects</a></li>
<li><a href="#all_implicit_binding">Implicit Binding</a></li>
<li><a href="#all_explicit_binding">Explicit Binding</a></li>
<li><a href="#all_domain_create">domain.create()</a></li>
<li><a href="#all_class_domain">Class: Domain</a><ul>
<li><a href="#all_domain_run_fn">domain.run(fn)</a></li>
<li><a href="#all_domain_members">domain.members</a></li>
<li><a href="#all_domain_add_emitter">domain.add(emitter)</a></li>
<li><a href="#all_domain_remove_emitter">domain.remove(emitter)</a></li>
<li><a href="#all_domain_bind_callback">domain.bind(callback)</a><ul>
<li><a href="#all_example">Example</a></li>
</ul>
</li>
<li><a href="#all_domain_intercept_callback">domain.intercept(callback)</a><ul>
<li><a href="#all_example_1">Example</a></li>
</ul>
</li>
<li><a href="#all_domain_enter">domain.enter()</a></li>
<li><a href="#all_domain_exit">domain.exit()</a></li>
<li><a href="#all_domain_dispose">domain.dispose()</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_buffer">Buffer</a><ul>
<li><a href="#all_class_buffer_1">Class: Buffer</a><ul>
<li><a href="#all_new_buffer_size">new Buffer(size)</a></li>
<li><a href="#all_new_buffer_array">new Buffer(array)</a></li>
<li><a href="#all_new_buffer_str_encoding">new Buffer(str, [encoding])</a></li>
<li><a href="#all_class_method_buffer_isencoding_encoding">Class Method: Buffer.isEncoding(encoding)</a></li>
<li><a href="#all_buf_write_string_offset_length_encoding">buf.write(string, [offset], [length], [encoding])</a></li>
<li><a href="#all_buf_tostring_encoding_start_end">buf.toString([encoding], [start], [end])</a></li>
<li><a href="#all_buf_tojson">buf.toJSON()</a></li>
<li><a href="#all_buf_index">buf[index]</a></li>
<li><a href="#all_class_method_buffer_isbuffer_obj">Class Method: Buffer.isBuffer(obj)</a></li>
<li><a href="#all_class_method_buffer_bytelength_string_encoding">Class Method: Buffer.byteLength(string, [encoding])</a></li>
<li><a href="#all_class_method_buffer_concat_list_totallength">Class Method: Buffer.concat(list, [totalLength])</a></li>
<li><a href="#all_buf_length">buf.length</a></li>
<li><a href="#all_buf_copy_targetbuffer_targetstart_sourcestart_sourceend">buf.copy(targetBuffer, [targetStart], [sourceStart], [sourceEnd])</a></li>
<li><a href="#all_buf_slice_start_end">buf.slice([start], [end])</a></li>
<li><a href="#all_buf_readuint8_offset_noassert">buf.readUInt8(offset, [noAssert])</a></li>
<li><a href="#all_buf_readuint16le_offset_noassert">buf.readUInt16LE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readuint16be_offset_noassert">buf.readUInt16BE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readuint32le_offset_noassert">buf.readUInt32LE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readuint32be_offset_noassert">buf.readUInt32BE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readint8_offset_noassert">buf.readInt8(offset, [noAssert])</a></li>
<li><a href="#all_buf_readint16le_offset_noassert">buf.readInt16LE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readint16be_offset_noassert">buf.readInt16BE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readint32le_offset_noassert">buf.readInt32LE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readint32be_offset_noassert">buf.readInt32BE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readfloatle_offset_noassert">buf.readFloatLE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readfloatbe_offset_noassert">buf.readFloatBE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readdoublele_offset_noassert">buf.readDoubleLE(offset, [noAssert])</a></li>
<li><a href="#all_buf_readdoublebe_offset_noassert">buf.readDoubleBE(offset, [noAssert])</a></li>
<li><a href="#all_buf_writeuint8_value_offset_noassert">buf.writeUInt8(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeuint16le_value_offset_noassert">buf.writeUInt16LE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeuint16be_value_offset_noassert">buf.writeUInt16BE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeuint32le_value_offset_noassert">buf.writeUInt32LE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeuint32be_value_offset_noassert">buf.writeUInt32BE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeint8_value_offset_noassert">buf.writeInt8(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeint16le_value_offset_noassert">buf.writeInt16LE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeint16be_value_offset_noassert">buf.writeInt16BE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeint32le_value_offset_noassert">buf.writeInt32LE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writeint32be_value_offset_noassert">buf.writeInt32BE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writefloatle_value_offset_noassert">buf.writeFloatLE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writefloatbe_value_offset_noassert">buf.writeFloatBE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writedoublele_value_offset_noassert">buf.writeDoubleLE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_writedoublebe_value_offset_noassert">buf.writeDoubleBE(value, offset, [noAssert])</a></li>
<li><a href="#all_buf_fill_value_offset_end">buf.fill(value, [offset], [end])</a></li>
</ul>
</li>
<li><a href="#all_buffer_inspect_max_bytes">buffer.INSPECT_MAX_BYTES</a></li>
<li><a href="#all_class_slowbuffer">Class: SlowBuffer</a></li>
</ul>
</li>
<li><a href="#all_stream">Stream</a><ul>
<li><a href="#all_api_for_stream_consumers">API for Stream Consumers</a><ul>
<li><a href="#all_class_stream_readable">Class: stream.Readable</a><ul>
<li><a href="#all_event_readable">Event: &#39;readable&#39;</a></li>
<li><a href="#all_event_data">Event: &#39;data&#39;</a></li>
<li><a href="#all_event_end">Event: &#39;end&#39;</a></li>
<li><a href="#all_event_close">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_error">Event: &#39;error&#39;</a></li>
<li><a href="#all_readable_read_size">readable.read([size])</a></li>
<li><a href="#all_readable_setencoding_encoding">readable.setEncoding(encoding)</a></li>
<li><a href="#all_readable_resume">readable.resume()</a></li>
<li><a href="#all_readable_pause">readable.pause()</a></li>
<li><a href="#all_readable_pipe_destination_options">readable.pipe(destination, [options])</a></li>
<li><a href="#all_readable_unpipe_destination">readable.unpipe([destination])</a></li>
<li><a href="#all_readable_unshift_chunk">readable.unshift(chunk)</a></li>
<li><a href="#all_readable_wrap_stream">readable.wrap(stream)</a></li>
</ul>
</li>
<li><a href="#all_class_stream_writable">Class: stream.Writable</a><ul>
<li><a href="#all_writable_write_chunk_encoding_callback">writable.write(chunk, [encoding], [callback])</a></li>
<li><a href="#all_event_drain">Event: &#39;drain&#39;</a></li>
<li><a href="#all_writable_end_chunk_encoding_callback">writable.end([chunk], [encoding], [callback])</a></li>
<li><a href="#all_event_finish">Event: &#39;finish&#39;</a></li>
<li><a href="#all_event_pipe">Event: &#39;pipe&#39;</a></li>
<li><a href="#all_event_unpipe">Event: &#39;unpipe&#39;</a></li>
<li><a href="#all_event_error_1">Event: &#39;error&#39;</a></li>
</ul>
</li>
<li><a href="#all_class_stream_duplex">Class: stream.Duplex</a></li>
<li><a href="#all_class_stream_transform">Class: stream.Transform</a></li>
</ul>
</li>
<li><a href="#all_api_for_stream_implementors">API for Stream Implementors</a><ul>
<li><a href="#all_class_stream_readable_1">Class: stream.Readable</a><ul>
<li><a href="#all_example_a_counting_stream">Example: A Counting Stream</a></li>
<li><a href="#all_example_simpleprotocol_v1_sub_optimal">Example: SimpleProtocol v1 (Sub-optimal)</a></li>
<li><a href="#all_new_stream_readable_options">new stream.Readable([options])</a></li>
<li><a href="#all_readable_read_size_1">readable._read(size)</a></li>
<li><a href="#all_readable_push_chunk_encoding">readable.push(chunk, [encoding])</a></li>
</ul>
</li>
<li><a href="#all_class_stream_writable_1">Class: stream.Writable</a><ul>
<li><a href="#all_new_stream_writable_options">new stream.Writable([options])</a></li>
<li><a href="#all_writable_write_chunk_encoding_callback_1">writable._write(chunk, encoding, callback)</a></li>
</ul>
</li>
<li><a href="#all_class_stream_duplex_1">Class: stream.Duplex</a><ul>
<li><a href="#all_new_stream_duplex_options">new stream.Duplex(options)</a></li>
</ul>
</li>
<li><a href="#all_class_stream_transform_1">Class: stream.Transform</a><ul>
<li><a href="#all_new_stream_transform_options">new stream.Transform([options])</a></li>
<li><a href="#all_transform_transform_chunk_encoding_callback">transform._transform(chunk, encoding, callback)</a></li>
<li><a href="#all_transform_flush_callback">transform._flush(callback)</a></li>
<li><a href="#all_example_simpleprotocol_parser_v2">Example: <code>SimpleProtocol</code> parser v2</a></li>
</ul>
</li>
<li><a href="#all_class_stream_passthrough">Class: stream.PassThrough</a></li>
</ul>
</li>
<li><a href="#all_streams_under_the_hood">Streams: Under the Hood</a><ul>
<li><a href="#all_buffering">Buffering</a></li>
<li><a href="#all_stream_read_0"><code>stream.read(0)</code></a></li>
<li><a href="#all_stream_push"><code>stream.push(&#39;&#39;)</code></a></li>
<li><a href="#all_compatibility_with_older_node_versions">Compatibility with Older Node Versions</a></li>
<li><a href="#all_object_mode">Object Mode</a></li>
<li><a href="#all_state_objects">State Objects</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_crypto">Crypto</a><ul>
<li><a href="#all_crypto_getciphers">crypto.getCiphers()</a></li>
<li><a href="#all_crypto_gethashes">crypto.getHashes()</a></li>
<li><a href="#all_crypto_createcredentials_details">crypto.createCredentials(details)</a></li>
<li><a href="#all_crypto_createhash_algorithm">crypto.createHash(algorithm)</a></li>
<li><a href="#all_class_hash">Class: Hash</a><ul>
<li><a href="#all_hash_update_data_input_encoding">hash.update(data, [input_encoding])</a></li>
<li><a href="#all_hash_digest_encoding">hash.digest([encoding])</a></li>
</ul>
</li>
<li><a href="#all_crypto_createhmac_algorithm_key">crypto.createHmac(algorithm, key)</a></li>
<li><a href="#all_class_hmac">Class: Hmac</a><ul>
<li><a href="#all_hmac_update_data">hmac.update(data)</a></li>
<li><a href="#all_hmac_digest_encoding">hmac.digest([encoding])</a></li>
</ul>
</li>
<li><a href="#all_crypto_createcipher_algorithm_password">crypto.createCipher(algorithm, password)</a></li>
<li><a href="#all_crypto_createcipheriv_algorithm_key_iv">crypto.createCipheriv(algorithm, key, iv)</a></li>
<li><a href="#all_class_cipher">Class: Cipher</a><ul>
<li><a href="#all_cipher_update_data_input_encoding_output_encoding">cipher.update(data, [input_encoding], [output_encoding])</a></li>
<li><a href="#all_cipher_final_output_encoding">cipher.final([output_encoding])</a></li>
<li><a href="#all_cipher_setautopadding_auto_padding_true">cipher.setAutoPadding(auto_padding=true)</a></li>
</ul>
</li>
<li><a href="#all_crypto_createdecipher_algorithm_password">crypto.createDecipher(algorithm, password)</a></li>
<li><a href="#all_crypto_createdecipheriv_algorithm_key_iv">crypto.createDecipheriv(algorithm, key, iv)</a></li>
<li><a href="#all_class_decipher">Class: Decipher</a><ul>
<li><a href="#all_decipher_update_data_input_encoding_output_encoding">decipher.update(data, [input_encoding], [output_encoding])</a></li>
<li><a href="#all_decipher_final_output_encoding">decipher.final([output_encoding])</a></li>
<li><a href="#all_decipher_setautopadding_auto_padding_true">decipher.setAutoPadding(auto_padding=true)</a></li>
</ul>
</li>
<li><a href="#all_crypto_createsign_algorithm">crypto.createSign(algorithm)</a></li>
<li><a href="#all_class_sign">Class: Sign</a><ul>
<li><a href="#all_sign_update_data">sign.update(data)</a></li>
<li><a href="#all_sign_sign_private_key_output_format">sign.sign(private_key, [output_format])</a></li>
</ul>
</li>
<li><a href="#all_crypto_createverify_algorithm">crypto.createVerify(algorithm)</a></li>
<li><a href="#all_class_verify">Class: Verify</a><ul>
<li><a href="#all_verifier_update_data">verifier.update(data)</a></li>
<li><a href="#all_verifier_verify_object_signature_signature_format">verifier.verify(object, signature, [signature_format])</a></li>
</ul>
</li>
<li><a href="#all_crypto_creatediffiehellman_prime_length">crypto.createDiffieHellman(prime_length)</a></li>
<li><a href="#all_crypto_creatediffiehellman_prime_encoding">crypto.createDiffieHellman(prime, [encoding])</a></li>
<li><a href="#all_class_diffiehellman">Class: DiffieHellman</a><ul>
<li><a href="#all_diffiehellman_generatekeys_encoding">diffieHellman.generateKeys([encoding])</a></li>
<li><a href="#all_diffiehellman_computesecret_other_public_key_input_encoding_output_encoding">diffieHellman.computeSecret(other_public_key, [input_encoding], [output_encoding])</a></li>
<li><a href="#all_diffiehellman_getprime_encoding">diffieHellman.getPrime([encoding])</a></li>
<li><a href="#all_diffiehellman_getgenerator_encoding">diffieHellman.getGenerator([encoding])</a></li>
<li><a href="#all_diffiehellman_getpublickey_encoding">diffieHellman.getPublicKey([encoding])</a></li>
<li><a href="#all_diffiehellman_getprivatekey_encoding">diffieHellman.getPrivateKey([encoding])</a></li>
<li><a href="#all_diffiehellman_setpublickey_public_key_encoding">diffieHellman.setPublicKey(public_key, [encoding])</a></li>
<li><a href="#all_diffiehellman_setprivatekey_private_key_encoding">diffieHellman.setPrivateKey(private_key, [encoding])</a></li>
</ul>
</li>
<li><a href="#all_crypto_getdiffiehellman_group_name">crypto.getDiffieHellman(group_name)</a></li>
<li><a href="#all_crypto_pbkdf2_password_salt_iterations_keylen_callback">crypto.pbkdf2(password, salt, iterations, keylen, callback)</a></li>
<li><a href="#all_crypto_pbkdf2sync_password_salt_iterations_keylen">crypto.pbkdf2Sync(password, salt, iterations, keylen)</a></li>
<li><a href="#all_crypto_randombytes_size_callback">crypto.randomBytes(size, [callback])</a></li>
<li><a href="#all_crypto_pseudorandombytes_size_callback">crypto.pseudoRandomBytes(size, [callback])</a></li>
<li><a href="#all_crypto_default_encoding">crypto.DEFAULT_ENCODING</a></li>
<li><a href="#all_recent_api_changes">Recent API Changes</a></li>
</ul>
</li>
<li><a href="#all_tls_ssl">TLS (SSL)</a><ul>
<li><a href="#all_client_initiated_renegotiation_attack_mitigation">Client-initiated renegotiation attack mitigation</a></li>
<li><a href="#all_npn_and_sni">NPN and SNI</a></li>
<li><a href="#all_tls_getciphers">tls.getCiphers()</a></li>
<li><a href="#all_tls_createserver_options_secureconnectionlistener">tls.createServer(options, [secureConnectionListener])</a></li>
<li><a href="#all_tls_slab_buffer_size">tls.SLAB_BUFFER_SIZE</a></li>
<li><a href="#all_tls_connect_options_callback">tls.connect(options, [callback])</a></li>
<li><a href="#all_tls_connect_port_host_options_callback">tls.connect(port, [host], [options], [callback])</a></li>
<li><a href="#all_tls_createsecurepair_credentials_isserver_requestcert_rejectunauthorized">tls.createSecurePair([credentials], [isServer], [requestCert], [rejectUnauthorized])</a></li>
<li><a href="#all_class_securepair">Class: SecurePair</a><ul>
<li><a href="#all_event_secure">Event: &#39;secure&#39;</a></li>
</ul>
</li>
<li><a href="#all_class_tls_server">Class: tls.Server</a><ul>
<li><a href="#all_event_secureconnection">Event: &#39;secureConnection&#39;</a></li>
<li><a href="#all_event_clienterror">Event: &#39;clientError&#39;</a></li>
<li><a href="#all_event_newsession">Event: &#39;newSession&#39;</a></li>
<li><a href="#all_event_resumesession">Event: &#39;resumeSession&#39;</a></li>
<li><a href="#all_server_listen_port_host_callback">server.listen(port, [host], [callback])</a></li>
<li><a href="#all_server_close">server.close()</a></li>
<li><a href="#all_server_address">server.address()</a></li>
<li><a href="#all_server_addcontext_hostname_credentials">server.addContext(hostname, credentials)</a></li>
<li><a href="#all_server_maxconnections">server.maxConnections</a></li>
<li><a href="#all_server_connections">server.connections</a></li>
</ul>
</li>
<li><a href="#all_class_cryptostream">Class: CryptoStream</a><ul>
<li><a href="#all_cryptostream_byteswritten">cryptoStream.bytesWritten</a></li>
</ul>
</li>
<li><a href="#all_class_tls_cleartextstream">Class: tls.CleartextStream</a><ul>
<li><a href="#all_event_secureconnect">Event: &#39;secureConnect&#39;</a></li>
<li><a href="#all_cleartextstream_authorized">cleartextStream.authorized</a></li>
<li><a href="#all_cleartextstream_authorizationerror">cleartextStream.authorizationError</a></li>
<li><a href="#all_cleartextstream_getpeercertificate">cleartextStream.getPeerCertificate()</a></li>
<li><a href="#all_cleartextstream_getcipher">cleartextStream.getCipher()</a></li>
<li><a href="#all_cleartextstream_address">cleartextStream.address()</a></li>
<li><a href="#all_cleartextstream_remoteaddress">cleartextStream.remoteAddress</a></li>
<li><a href="#all_cleartextstream_remoteport">cleartextStream.remotePort</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_stringdecoder">StringDecoder</a><ul>
<li><a href="#all_class_stringdecoder">Class: StringDecoder</a><ul>
<li><a href="#all_decoder_write_buffer">decoder.write(buffer)</a></li>
<li><a href="#all_decoder_end">decoder.end()</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_file_system">File System</a><ul>
<li><a href="#all_fs_rename_oldpath_newpath_callback">fs.rename(oldPath, newPath, callback)</a></li>
<li><a href="#all_fs_renamesync_oldpath_newpath">fs.renameSync(oldPath, newPath)</a></li>
<li><a href="#all_fs_ftruncate_fd_len_callback">fs.ftruncate(fd, len, callback)</a></li>
<li><a href="#all_fs_ftruncatesync_fd_len">fs.ftruncateSync(fd, len)</a></li>
<li><a href="#all_fs_truncate_path_len_callback">fs.truncate(path, len, callback)</a></li>
<li><a href="#all_fs_truncatesync_path_len">fs.truncateSync(path, len)</a></li>
<li><a href="#all_fs_chown_path_uid_gid_callback">fs.chown(path, uid, gid, callback)</a></li>
<li><a href="#all_fs_chownsync_path_uid_gid">fs.chownSync(path, uid, gid)</a></li>
<li><a href="#all_fs_fchown_fd_uid_gid_callback">fs.fchown(fd, uid, gid, callback)</a></li>
<li><a href="#all_fs_fchownsync_fd_uid_gid">fs.fchownSync(fd, uid, gid)</a></li>
<li><a href="#all_fs_lchown_path_uid_gid_callback">fs.lchown(path, uid, gid, callback)</a></li>
<li><a href="#all_fs_lchownsync_path_uid_gid">fs.lchownSync(path, uid, gid)</a></li>
<li><a href="#all_fs_chmod_path_mode_callback">fs.chmod(path, mode, callback)</a></li>
<li><a href="#all_fs_chmodsync_path_mode">fs.chmodSync(path, mode)</a></li>
<li><a href="#all_fs_fchmod_fd_mode_callback">fs.fchmod(fd, mode, callback)</a></li>
<li><a href="#all_fs_fchmodsync_fd_mode">fs.fchmodSync(fd, mode)</a></li>
<li><a href="#all_fs_lchmod_path_mode_callback">fs.lchmod(path, mode, callback)</a></li>
<li><a href="#all_fs_lchmodsync_path_mode">fs.lchmodSync(path, mode)</a></li>
<li><a href="#all_fs_stat_path_callback">fs.stat(path, callback)</a></li>
<li><a href="#all_fs_lstat_path_callback">fs.lstat(path, callback)</a></li>
<li><a href="#all_fs_fstat_fd_callback">fs.fstat(fd, callback)</a></li>
<li><a href="#all_fs_statsync_path">fs.statSync(path)</a></li>
<li><a href="#all_fs_lstatsync_path">fs.lstatSync(path)</a></li>
<li><a href="#all_fs_fstatsync_fd">fs.fstatSync(fd)</a></li>
<li><a href="#all_fs_link_srcpath_dstpath_callback">fs.link(srcpath, dstpath, callback)</a></li>
<li><a href="#all_fs_linksync_srcpath_dstpath">fs.linkSync(srcpath, dstpath)</a></li>
<li><a href="#all_fs_symlink_srcpath_dstpath_type_callback">fs.symlink(srcpath, dstpath, [type], callback)</a></li>
<li><a href="#all_fs_symlinksync_srcpath_dstpath_type">fs.symlinkSync(srcpath, dstpath, [type])</a></li>
<li><a href="#all_fs_readlink_path_callback">fs.readlink(path, callback)</a></li>
<li><a href="#all_fs_readlinksync_path">fs.readlinkSync(path)</a></li>
<li><a href="#all_fs_realpath_path_cache_callback">fs.realpath(path, [cache], callback)</a></li>
<li><a href="#all_fs_realpathsync_path_cache">fs.realpathSync(path, [cache])</a></li>
<li><a href="#all_fs_unlink_path_callback">fs.unlink(path, callback)</a></li>
<li><a href="#all_fs_unlinksync_path">fs.unlinkSync(path)</a></li>
<li><a href="#all_fs_rmdir_path_callback">fs.rmdir(path, callback)</a></li>
<li><a href="#all_fs_rmdirsync_path">fs.rmdirSync(path)</a></li>
<li><a href="#all_fs_mkdir_path_mode_callback">fs.mkdir(path, [mode], callback)</a></li>
<li><a href="#all_fs_mkdirsync_path_mode">fs.mkdirSync(path, [mode])</a></li>
<li><a href="#all_fs_readdir_path_callback">fs.readdir(path, callback)</a></li>
<li><a href="#all_fs_readdirsync_path">fs.readdirSync(path)</a></li>
<li><a href="#all_fs_close_fd_callback">fs.close(fd, callback)</a></li>
<li><a href="#all_fs_closesync_fd">fs.closeSync(fd)</a></li>
<li><a href="#all_fs_open_path_flags_mode_callback">fs.open(path, flags, [mode], callback)</a></li>
<li><a href="#all_fs_opensync_path_flags_mode">fs.openSync(path, flags, [mode])</a></li>
<li><a href="#all_fs_utimes_path_atime_mtime_callback">fs.utimes(path, atime, mtime, callback)</a></li>
<li><a href="#all_fs_utimessync_path_atime_mtime">fs.utimesSync(path, atime, mtime)</a></li>
<li><a href="#all_fs_futimes_fd_atime_mtime_callback">fs.futimes(fd, atime, mtime, callback)</a></li>
<li><a href="#all_fs_futimessync_fd_atime_mtime">fs.futimesSync(fd, atime, mtime)</a></li>
<li><a href="#all_fs_fsync_fd_callback">fs.fsync(fd, callback)</a></li>
<li><a href="#all_fs_fsyncsync_fd">fs.fsyncSync(fd)</a></li>
<li><a href="#all_fs_write_fd_buffer_offset_length_position_callback">fs.write(fd, buffer, offset, length, position, callback)</a></li>
<li><a href="#all_fs_writesync_fd_buffer_offset_length_position">fs.writeSync(fd, buffer, offset, length, position)</a></li>
<li><a href="#all_fs_read_fd_buffer_offset_length_position_callback">fs.read(fd, buffer, offset, length, position, callback)</a></li>
<li><a href="#all_fs_readsync_fd_buffer_offset_length_position">fs.readSync(fd, buffer, offset, length, position)</a></li>
<li><a href="#all_fs_readfile_filename_options_callback">fs.readFile(filename, [options], callback)</a></li>
<li><a href="#all_fs_readfilesync_filename_options">fs.readFileSync(filename, [options])</a></li>
<li><a href="#all_fs_writefile_filename_data_options_callback">fs.writeFile(filename, data, [options], callback)</a></li>
<li><a href="#all_fs_writefilesync_filename_data_options">fs.writeFileSync(filename, data, [options])</a></li>
<li><a href="#all_fs_appendfile_filename_data_options_callback">fs.appendFile(filename, data, [options], callback)</a></li>
<li><a href="#all_fs_appendfilesync_filename_data_options">fs.appendFileSync(filename, data, [options])</a></li>
<li><a href="#all_fs_watchfile_filename_options_listener">fs.watchFile(filename, [options], listener)</a></li>
<li><a href="#all_fs_unwatchfile_filename_listener">fs.unwatchFile(filename, [listener])</a></li>
<li><a href="#all_fs_watch_filename_options_listener">fs.watch(filename, [options], [listener])</a><ul>
<li><a href="#all_caveats">Caveats</a><ul>
<li><a href="#all_availability">Availability</a></li>
<li><a href="#all_filename_argument">Filename Argument</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_fs_exists_path_callback">fs.exists(path, callback)</a></li>
<li><a href="#all_fs_existssync_path">fs.existsSync(path)</a></li>
<li><a href="#all_class_fs_stats">Class: fs.Stats</a></li>
<li><a href="#all_fs_createreadstream_path_options">fs.createReadStream(path, [options])</a></li>
<li><a href="#all_class_fs_readstream">Class: fs.ReadStream</a><ul>
<li><a href="#all_event_open">Event: &#39;open&#39;</a></li>
</ul>
</li>
<li><a href="#all_fs_createwritestream_path_options">fs.createWriteStream(path, [options])</a></li>
<li><a href="#all_class_fs_writestream">Class: fs.WriteStream</a><ul>
<li><a href="#all_event_open_1">Event: &#39;open&#39;</a></li>
<li><a href="#all_file_byteswritten">file.bytesWritten</a></li>
</ul>
</li>
<li><a href="#all_class_fs_fswatcher">Class: fs.FSWatcher</a><ul>
<li><a href="#all_watcher_close">watcher.close()</a></li>
<li><a href="#all_event_change">Event: &#39;change&#39;</a></li>
<li><a href="#all_event_error_2">Event: &#39;error&#39;</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_path">Path</a><ul>
<li><a href="#all_path_normalize_p">path.normalize(p)</a></li>
<li><a href="#all_path_join_path1_path2">path.join([path1], [path2], [...])</a></li>
<li><a href="#all_path_resolve_from_to">path.resolve([from ...], to)</a></li>
<li><a href="#all_path_relative_from_to">path.relative(from, to)</a></li>
<li><a href="#all_path_dirname_p">path.dirname(p)</a></li>
<li><a href="#all_path_basename_p_ext">path.basename(p, [ext])</a></li>
<li><a href="#all_path_extname_p">path.extname(p)</a></li>
<li><a href="#all_path_sep">path.sep</a></li>
<li><a href="#all_path_delimiter">path.delimiter</a></li>
</ul>
</li>
<li><a href="#all_net">net</a><ul>
<li><a href="#all_net_createserver_options_connectionlistener">net.createServer([options], [connectionListener])</a></li>
<li><a href="#all_net_connect_options_connectionlistener">net.connect(options, [connectionListener])</a></li>
<li><a href="#all_net_createconnection_options_connectionlistener">net.createConnection(options, [connectionListener])</a></li>
<li><a href="#all_net_connect_port_host_connectlistener">net.connect(port, [host], [connectListener])</a></li>
<li><a href="#all_net_createconnection_port_host_connectlistener">net.createConnection(port, [host], [connectListener])</a></li>
<li><a href="#all_net_connect_path_connectlistener">net.connect(path, [connectListener])</a></li>
<li><a href="#all_net_createconnection_path_connectlistener">net.createConnection(path, [connectListener])</a></li>
<li><a href="#all_class_net_server">Class: net.Server</a><ul>
<li><a href="#all_server_listen_port_host_backlog_callback">server.listen(port, [host], [backlog], [callback])</a></li>
<li><a href="#all_server_listen_path_callback">server.listen(path, [callback])</a></li>
<li><a href="#all_server_listen_handle_callback">server.listen(handle, [callback])</a></li>
<li><a href="#all_server_close_callback">server.close([callback])</a></li>
<li><a href="#all_server_address_1">server.address()</a></li>
<li><a href="#all_server_unref">server.unref()</a></li>
<li><a href="#all_server_ref">server.ref()</a></li>
<li><a href="#all_server_maxconnections_1">server.maxConnections</a></li>
<li><a href="#all_server_connections_1">server.connections</a></li>
<li><a href="#all_server_getconnections_callback">server.getConnections(callback)</a></li>
<li><a href="#all_event_listening">Event: &#39;listening&#39;</a></li>
<li><a href="#all_event_connection">Event: &#39;connection&#39;</a></li>
<li><a href="#all_event_close_1">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_error_3">Event: &#39;error&#39;</a></li>
</ul>
</li>
<li><a href="#all_class_net_socket">Class: net.Socket</a><ul>
<li><a href="#all_new_net_socket_options">new net.Socket([options])</a></li>
<li><a href="#all_socket_connect_port_host_connectlistener">socket.connect(port, [host], [connectListener])</a></li>
<li><a href="#all_socket_connect_path_connectlistener">socket.connect(path, [connectListener])</a></li>
<li><a href="#all_socket_buffersize">socket.bufferSize</a></li>
<li><a href="#all_socket_setencoding_encoding">socket.setEncoding([encoding])</a></li>
<li><a href="#all_socket_write_data_encoding_callback">socket.write(data, [encoding], [callback])</a></li>
<li><a href="#all_socket_end_data_encoding">socket.end([data], [encoding])</a></li>
<li><a href="#all_socket_destroy">socket.destroy()</a></li>
<li><a href="#all_socket_pause">socket.pause()</a></li>
<li><a href="#all_socket_resume">socket.resume()</a></li>
<li><a href="#all_socket_settimeout_timeout_callback">socket.setTimeout(timeout, [callback])</a></li>
<li><a href="#all_socket_setnodelay_nodelay">socket.setNoDelay([noDelay])</a></li>
<li><a href="#all_socket_setkeepalive_enable_initialdelay">socket.setKeepAlive([enable], [initialDelay])</a></li>
<li><a href="#all_socket_address">socket.address()</a></li>
<li><a href="#all_socket_unref">socket.unref()</a></li>
<li><a href="#all_socket_ref">socket.ref()</a></li>
<li><a href="#all_socket_remoteaddress">socket.remoteAddress</a></li>
<li><a href="#all_socket_remoteport">socket.remotePort</a></li>
<li><a href="#all_socket_localaddress">socket.localAddress</a></li>
<li><a href="#all_socket_localport">socket.localPort</a></li>
<li><a href="#all_socket_bytesread">socket.bytesRead</a></li>
<li><a href="#all_socket_byteswritten">socket.bytesWritten</a></li>
<li><a href="#all_event_connect">Event: &#39;connect&#39;</a></li>
<li><a href="#all_event_data_1">Event: &#39;data&#39;</a></li>
<li><a href="#all_event_end_1">Event: &#39;end&#39;</a></li>
<li><a href="#all_event_timeout">Event: &#39;timeout&#39;</a></li>
<li><a href="#all_event_drain_1">Event: &#39;drain&#39;</a></li>
<li><a href="#all_event_error_4">Event: &#39;error&#39;</a></li>
<li><a href="#all_event_close_2">Event: &#39;close&#39;</a></li>
</ul>
</li>
<li><a href="#all_net_isip_input">net.isIP(input)</a></li>
<li><a href="#all_net_isipv4_input">net.isIPv4(input)</a></li>
<li><a href="#all_net_isipv6_input">net.isIPv6(input)</a></li>
</ul>
</li>
<li><a href="#all_udp_datagram_sockets">UDP / Datagram Sockets</a><ul>
<li><a href="#all_dgram_createsocket_type_callback">dgram.createSocket(type, [callback])</a></li>
<li><a href="#all_class_dgram_socket">Class: dgram.Socket</a><ul>
<li><a href="#all_event_message">Event: &#39;message&#39;</a></li>
<li><a href="#all_event_listening_1">Event: &#39;listening&#39;</a></li>
<li><a href="#all_event_close_3">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_error_5">Event: &#39;error&#39;</a></li>
<li><a href="#all_socket_send_buf_offset_length_port_address_callback">socket.send(buf, offset, length, port, address, [callback])</a></li>
<li><a href="#all_socket_bind_port_address_callback">socket.bind(port, [address], [callback])</a></li>
<li><a href="#all_socket_close">socket.close()</a></li>
<li><a href="#all_socket_address_1">socket.address()</a></li>
<li><a href="#all_socket_setbroadcast_flag">socket.setBroadcast(flag)</a></li>
<li><a href="#all_socket_setttl_ttl">socket.setTTL(ttl)</a></li>
<li><a href="#all_socket_setmulticastttl_ttl">socket.setMulticastTTL(ttl)</a></li>
<li><a href="#all_socket_setmulticastloopback_flag">socket.setMulticastLoopback(flag)</a></li>
<li><a href="#all_socket_addmembership_multicastaddress_multicastinterface">socket.addMembership(multicastAddress, [multicastInterface])</a></li>
<li><a href="#all_socket_dropmembership_multicastaddress_multicastinterface">socket.dropMembership(multicastAddress, [multicastInterface])</a></li>
<li><a href="#all_socket_unref_1">socket.unref()</a></li>
<li><a href="#all_socket_ref_1">socket.ref()</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_dns">DNS</a><ul>
<li><a href="#all_dns_lookup_domain_family_callback">dns.lookup(domain, [family], callback)</a></li>
<li><a href="#all_dns_resolve_domain_rrtype_callback">dns.resolve(domain, [rrtype], callback)</a></li>
<li><a href="#all_dns_resolve4_domain_callback">dns.resolve4(domain, callback)</a></li>
<li><a href="#all_dns_resolve6_domain_callback">dns.resolve6(domain, callback)</a></li>
<li><a href="#all_dns_resolvemx_domain_callback">dns.resolveMx(domain, callback)</a></li>
<li><a href="#all_dns_resolvetxt_domain_callback">dns.resolveTxt(domain, callback)</a></li>
<li><a href="#all_dns_resolvesrv_domain_callback">dns.resolveSrv(domain, callback)</a></li>
<li><a href="#all_dns_resolvens_domain_callback">dns.resolveNs(domain, callback)</a></li>
<li><a href="#all_dns_resolvecname_domain_callback">dns.resolveCname(domain, callback)</a></li>
<li><a href="#all_dns_reverse_ip_callback">dns.reverse(ip, callback)</a></li>
<li><a href="#all_error_codes">Error codes</a></li>
</ul>
</li>
<li><a href="#all_http">HTTP</a><ul>
<li><a href="#all_http_status_codes">http.STATUS_CODES</a></li>
<li><a href="#all_http_createserver_requestlistener">http.createServer([requestListener])</a></li>
<li><a href="#all_http_createclient_port_host">http.createClient([port], [host])</a></li>
<li><a href="#all_class_http_server">Class: http.Server</a><ul>
<li><a href="#all_event_request">Event: &#39;request&#39;</a></li>
<li><a href="#all_event_connection_1">Event: &#39;connection&#39;</a></li>
<li><a href="#all_event_close_4">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_checkcontinue">Event: &#39;checkContinue&#39;</a></li>
<li><a href="#all_event_connect_1">Event: &#39;connect&#39;</a></li>
<li><a href="#all_event_upgrade">Event: &#39;upgrade&#39;</a></li>
<li><a href="#all_event_clienterror_1">Event: &#39;clientError&#39;</a></li>
<li><a href="#all_server_listen_port_hostname_backlog_callback">server.listen(port, [hostname], [backlog], [callback])</a></li>
<li><a href="#all_server_listen_path_callback_1">server.listen(path, [callback])</a></li>
<li><a href="#all_server_listen_handle_callback_1">server.listen(handle, [callback])</a></li>
<li><a href="#all_server_close_callback_1">server.close([callback])</a></li>
<li><a href="#all_server_maxheaderscount">server.maxHeadersCount</a></li>
<li><a href="#all_server_settimeout_msecs_callback">server.setTimeout(msecs, callback)</a></li>
<li><a href="#all_server_timeout">server.timeout</a></li>
</ul>
</li>
<li><a href="#all_class_http_serverresponse">Class: http.ServerResponse</a><ul>
<li><a href="#all_event_close_5">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_finish_1">Event: &#39;finish&#39;</a></li>
<li><a href="#all_response_writecontinue">response.writeContinue()</a></li>
<li><a href="#all_response_writehead_statuscode_reasonphrase_headers">response.writeHead(statusCode, [reasonPhrase], [headers])</a></li>
<li><a href="#all_response_settimeout_msecs_callback">response.setTimeout(msecs, callback)</a></li>
<li><a href="#all_response_statuscode">response.statusCode</a></li>
<li><a href="#all_response_setheader_name_value">response.setHeader(name, value)</a></li>
<li><a href="#all_response_headerssent">response.headersSent</a></li>
<li><a href="#all_response_senddate">response.sendDate</a></li>
<li><a href="#all_response_getheader_name">response.getHeader(name)</a></li>
<li><a href="#all_response_removeheader_name">response.removeHeader(name)</a></li>
<li><a href="#all_response_write_chunk_encoding">response.write(chunk, [encoding])</a></li>
<li><a href="#all_response_addtrailers_headers">response.addTrailers(headers)</a></li>
<li><a href="#all_response_end_data_encoding">response.end([data], [encoding])</a></li>
</ul>
</li>
<li><a href="#all_http_request_options_callback">http.request(options, [callback])</a></li>
<li><a href="#all_http_get_options_callback">http.get(options, [callback])</a></li>
<li><a href="#all_class_http_agent">Class: http.Agent</a><ul>
<li><a href="#all_agent_maxsockets">agent.maxSockets</a></li>
<li><a href="#all_agent_sockets">agent.sockets</a></li>
<li><a href="#all_agent_requests">agent.requests</a></li>
</ul>
</li>
<li><a href="#all_http_globalagent">http.globalAgent</a></li>
<li><a href="#all_class_http_clientrequest">Class: http.ClientRequest</a><ul>
<li><a href="#all_event_response">Event &#39;response&#39;</a></li>
<li><a href="#all_event_socket">Event: &#39;socket&#39;</a></li>
<li><a href="#all_event_connect_2">Event: &#39;connect&#39;</a></li>
<li><a href="#all_event_upgrade_1">Event: &#39;upgrade&#39;</a></li>
<li><a href="#all_event_continue">Event: &#39;continue&#39;</a></li>
<li><a href="#all_request_write_chunk_encoding">request.write(chunk, [encoding])</a></li>
<li><a href="#all_request_end_data_encoding">request.end([data], [encoding])</a></li>
<li><a href="#all_request_abort">request.abort()</a></li>
<li><a href="#all_request_settimeout_timeout_callback">request.setTimeout(timeout, [callback])</a></li>
<li><a href="#all_request_setnodelay_nodelay">request.setNoDelay([noDelay])</a></li>
<li><a href="#all_request_setsocketkeepalive_enable_initialdelay">request.setSocketKeepAlive([enable], [initialDelay])</a></li>
</ul>
</li>
<li><a href="#all_http_incomingmessage">http.IncomingMessage</a><ul>
<li><a href="#all_event_close_6">Event: &#39;close&#39;</a></li>
<li><a href="#all_message_httpversion">message.httpVersion</a></li>
<li><a href="#all_message_headers">message.headers</a></li>
<li><a href="#all_message_trailers">message.trailers</a></li>
<li><a href="#all_message_settimeout_msecs_callback">message.setTimeout(msecs, callback)</a></li>
<li><a href="#all_message_method">message.method</a></li>
<li><a href="#all_message_url">message.url</a></li>
<li><a href="#all_message_statuscode">message.statusCode</a></li>
<li><a href="#all_message_socket">message.socket</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_https">HTTPS</a><ul>
<li><a href="#all_class_https_server">Class: https.Server</a></li>
<li><a href="#all_https_createserver_options_requestlistener">https.createServer(options, [requestListener])</a><ul>
<li><a href="#all_server_listen_port_host_backlog_callback_1">server.listen(port, [host], [backlog], [callback])</a></li>
<li><a href="#all_server_listen_path_callback_2">server.listen(path, [callback])</a></li>
<li><a href="#all_server_listen_handle_callback_2">server.listen(handle, [callback])</a></li>
<li><a href="#all_server_close_callback_2">server.close([callback])</a></li>
</ul>
</li>
<li><a href="#all_https_request_options_callback">https.request(options, callback)</a></li>
<li><a href="#all_https_get_options_callback">https.get(options, callback)</a></li>
<li><a href="#all_class_https_agent">Class: https.Agent</a></li>
<li><a href="#all_https_globalagent">https.globalAgent</a></li>
</ul>
</li>
<li><a href="#all_url">URL</a><ul>
<li><a href="#all_url_parse_urlstr_parsequerystring_slashesdenotehost">url.parse(urlStr, [parseQueryString], [slashesDenoteHost])</a></li>
<li><a href="#all_url_format_urlobj">url.format(urlObj)</a></li>
<li><a href="#all_url_resolve_from_to">url.resolve(from, to)</a></li>
</ul>
</li>
<li><a href="#all_query_string">Query String</a><ul>
<li><a href="#all_querystring_stringify_obj_sep_eq">querystring.stringify(obj, [sep], [eq])</a></li>
<li><a href="#all_querystring_parse_str_sep_eq_options">querystring.parse(str, [sep], [eq], [options])</a></li>
<li><a href="#all_querystring_escape">querystring.escape</a></li>
<li><a href="#all_querystring_unescape">querystring.unescape</a></li>
</ul>
</li>
<li><a href="#all_punycode">punycode</a><ul>
<li><a href="#all_punycode_decode_string">punycode.decode(string)</a></li>
<li><a href="#all_punycode_encode_string">punycode.encode(string)</a></li>
<li><a href="#all_punycode_tounicode_domain">punycode.toUnicode(domain)</a></li>
<li><a href="#all_punycode_toascii_domain">punycode.toASCII(domain)</a></li>
<li><a href="#all_punycode_ucs2">punycode.ucs2</a><ul>
<li><a href="#all_punycode_ucs2_decode_string">punycode.ucs2.decode(string)</a></li>
<li><a href="#all_punycode_ucs2_encode_codepoints">punycode.ucs2.encode(codePoints)</a></li>
</ul>
</li>
<li><a href="#all_punycode_version">punycode.version</a></li>
</ul>
</li>
<li><a href="#all_readline">Readline</a><ul>
<li><a href="#all_readline_createinterface_options">readline.createInterface(options)</a></li>
<li><a href="#all_class_interface">Class: Interface</a><ul>
<li><a href="#all_rl_setprompt_prompt_length">rl.setPrompt(prompt, length)</a></li>
<li><a href="#all_rl_prompt_preservecursor">rl.prompt([preserveCursor])</a></li>
<li><a href="#all_rl_question_query_callback">rl.question(query, callback)</a></li>
<li><a href="#all_rl_pause">rl.pause()</a></li>
<li><a href="#all_rl_resume">rl.resume()</a></li>
<li><a href="#all_rl_close">rl.close()</a></li>
<li><a href="#all_rl_write_data_key">rl.write(data, [key])</a></li>
</ul>
</li>
<li><a href="#all_events_1">Events</a><ul>
<li><a href="#all_event_line">Event: &#39;line&#39;</a></li>
<li><a href="#all_event_pause">Event: &#39;pause&#39;</a></li>
<li><a href="#all_event_resume">Event: &#39;resume&#39;</a></li>
<li><a href="#all_event_close_7">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_sigint">Event: &#39;SIGINT&#39;</a></li>
<li><a href="#all_event_sigtstp">Event: &#39;SIGTSTP&#39;</a></li>
<li><a href="#all_event_sigcont">Event: &#39;SIGCONT&#39;</a></li>
</ul>
</li>
<li><a href="#all_example_tiny_cli">Example: Tiny CLI</a></li>
</ul>
</li>
<li><a href="#all_repl">REPL</a><ul>
<li><a href="#all_repl_start_options">repl.start(options)</a><ul>
<li><a href="#all_event_exit_1">Event: &#39;exit&#39;</a></li>
</ul>
</li>
<li><a href="#all_repl_features">REPL Features</a></li>
</ul>
</li>
<li><a href="#all_executing_javascript">Executing JavaScript</a><ul>
<li><a href="#all_caveats_1">Caveats</a><ul>
<li><a href="#all_sandboxes">Sandboxes</a></li>
<li><a href="#all_globals">Globals</a></li>
</ul>
</li>
<li><a href="#all_vm_runinthiscontext_code_filename">vm.runInThisContext(code, [filename])</a></li>
<li><a href="#all_vm_runinnewcontext_code_sandbox_filename">vm.runInNewContext(code, [sandbox], [filename])</a></li>
<li><a href="#all_vm_runincontext_code_context_filename">vm.runInContext(code, context, [filename])</a></li>
<li><a href="#all_vm_createcontext_initsandbox">vm.createContext([initSandbox])</a></li>
<li><a href="#all_vm_createscript_code_filename">vm.createScript(code, [filename])</a></li>
<li><a href="#all_class_script">Class: Script</a><ul>
<li><a href="#all_script_runinthiscontext">script.runInThisContext()</a></li>
<li><a href="#all_script_runinnewcontext_sandbox">script.runInNewContext([sandbox])</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_child_process">Child Process</a><ul>
<li><a href="#all_class_childprocess">Class: ChildProcess</a><ul>
<li><a href="#all_event_error_6">Event: &#39;error&#39;</a></li>
<li><a href="#all_event_exit_2">Event: &#39;exit&#39;</a></li>
<li><a href="#all_event_close_8">Event: &#39;close&#39;</a></li>
<li><a href="#all_event_disconnect">Event: &#39;disconnect&#39;</a></li>
<li><a href="#all_event_message_1">Event: &#39;message&#39;</a></li>
<li><a href="#all_child_stdin">child.stdin</a></li>
<li><a href="#all_child_stdout">child.stdout</a></li>
<li><a href="#all_child_stderr">child.stderr</a></li>
<li><a href="#all_child_pid">child.pid</a></li>
<li><a href="#all_child_connected">child.connected</a></li>
<li><a href="#all_child_kill_signal">child.kill([signal])</a></li>
<li><a href="#all_child_send_message_sendhandle">child.send(message, [sendHandle])</a><ul>
<li><a href="#all_example_sending_server_object">Example: sending server object</a></li>
<li><a href="#all_example_sending_socket_object">Example: sending socket object</a></li>
</ul>
</li>
<li><a href="#all_child_disconnect">child.disconnect()</a></li>
</ul>
</li>
<li><a href="#all_child_process_spawn_command_args_options">child_process.spawn(command, [args], [options])</a></li>
<li><a href="#all_child_process_exec_command_options_callback">child_process.exec(command, [options], callback)</a></li>
<li><a href="#all_child_process_execfile_file_args_options_callback">child_process.execFile(file, args, options, callback)</a></li>
<li><a href="#all_child_process_fork_modulepath_args_options">child_process.fork(modulePath, [args], [options])</a></li>
</ul>
</li>
<li><a href="#all_assert">Assert</a><ul>
<li><a href="#all_assert_fail_actual_expected_message_operator">assert.fail(actual, expected, message, operator)</a></li>
<li><a href="#all_assert_value_message_assert_ok_value_message">assert(value, message), assert.ok(value, [message])</a></li>
<li><a href="#all_assert_equal_actual_expected_message">assert.equal(actual, expected, [message])</a></li>
<li><a href="#all_assert_notequal_actual_expected_message">assert.notEqual(actual, expected, [message])</a></li>
<li><a href="#all_assert_deepequal_actual_expected_message">assert.deepEqual(actual, expected, [message])</a></li>
<li><a href="#all_assert_notdeepequal_actual_expected_message">assert.notDeepEqual(actual, expected, [message])</a></li>
<li><a href="#all_assert_strictequal_actual_expected_message">assert.strictEqual(actual, expected, [message])</a></li>
<li><a href="#all_assert_notstrictequal_actual_expected_message">assert.notStrictEqual(actual, expected, [message])</a></li>
<li><a href="#all_assert_throws_block_error_message">assert.throws(block, [error], [message])</a></li>
<li><a href="#all_assert_doesnotthrow_block_message">assert.doesNotThrow(block, [message])</a></li>
<li><a href="#all_assert_iferror_value">assert.ifError(value)</a></li>
</ul>
</li>
<li><a href="#all_tty">TTY</a><ul>
<li><a href="#all_tty_isatty_fd">tty.isatty(fd)</a></li>
<li><a href="#all_tty_setrawmode_mode">tty.setRawMode(mode)</a></li>
<li><a href="#all_class_readstream">Class: ReadStream</a><ul>
<li><a href="#all_rs_israw">rs.isRaw</a></li>
<li><a href="#all_rs_setrawmode_mode">rs.setRawMode(mode)</a></li>
</ul>
</li>
<li><a href="#all_class_writestream">Class: WriteStream</a><ul>
<li><a href="#all_ws_columns">ws.columns</a></li>
<li><a href="#all_ws_rows">ws.rows</a></li>
<li><a href="#all_event_resize">Event: &#39;resize&#39;</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#all_zlib">Zlib</a><ul>
<li><a href="#all_examples">Examples</a></li>
<li><a href="#all_zlib_creategzip_options">zlib.createGzip([options])</a></li>
<li><a href="#all_zlib_creategunzip_options">zlib.createGunzip([options])</a></li>
<li><a href="#all_zlib_createdeflate_options">zlib.createDeflate([options])</a></li>
<li><a href="#all_zlib_createinflate_options">zlib.createInflate([options])</a></li>
<li><a href="#all_zlib_createdeflateraw_options">zlib.createDeflateRaw([options])</a></li>
<li><a href="#all_zlib_createinflateraw_options">zlib.createInflateRaw([options])</a></li>
<li><a href="#all_zlib_createunzip_options">zlib.createUnzip([options])</a></li>
<li><a href="#all_class_zlib_zlib">Class: zlib.Zlib</a><ul>
<li><a href="#all_zlib_flush_callback">zlib.flush(callback)</a></li>
<li><a href="#all_zlib_reset">zlib.reset()</a></li>
</ul>
</li>
<li><a href="#all_class_zlib_gzip">Class: zlib.Gzip</a></li>
<li><a href="#all_class_zlib_gunzip">Class: zlib.Gunzip</a></li>
<li><a href="#all_class_zlib_deflate">Class: zlib.Deflate</a></li>
<li><a href="#all_class_zlib_inflate">Class: zlib.Inflate</a></li>
<li><a href="#all_class_zlib_deflateraw">Class: zlib.DeflateRaw</a></li>
<li><a href="#all_class_zlib_inflateraw">Class: zlib.InflateRaw</a></li>
<li><a href="#all_class_zlib_unzip">Class: zlib.Unzip</a></li>
<li><a href="#all_convenience_methods">Convenience Methods</a></li>
<li><a href="#all_zlib_deflate_buf_callback">zlib.deflate(buf, callback)</a></li>
<li><a href="#all_zlib_deflateraw_buf_callback">zlib.deflateRaw(buf, callback)</a></li>
<li><a href="#all_zlib_gzip_buf_callback">zlib.gzip(buf, callback)</a></li>
<li><a href="#all_zlib_gunzip_buf_callback">zlib.gunzip(buf, callback)</a></li>
<li><a href="#all_zlib_inflate_buf_callback">zlib.inflate(buf, callback)</a></li>
<li><a href="#all_zlib_inflateraw_buf_callback">zlib.inflateRaw(buf, callback)</a></li>
<li><a href="#all_zlib_unzip_buf_callback">zlib.unzip(buf, callback)</a></li>
<li><a href="#all_options">Options</a></li>
<li><a href="#all_memory_usage_tuning">Memory Usage Tuning</a></li>
<li><a href="#all_constants">Constants</a></li>
</ul>
</li>
<li><a href="#all_os">os</a><ul>
<li><a href="#all_os_tmpdir">os.tmpdir()</a></li>
<li><a href="#all_os_endianness">os.endianness()</a></li>
<li><a href="#all_os_hostname">os.hostname()</a></li>
<li><a href="#all_os_type">os.type()</a></li>
<li><a href="#all_os_platform">os.platform()</a></li>
<li><a href="#all_os_arch">os.arch()</a></li>
<li><a href="#all_os_release">os.release()</a></li>
<li><a href="#all_os_uptime">os.uptime()</a></li>
<li><a href="#all_os_loadavg">os.loadavg()</a></li>
<li><a href="#all_os_totalmem">os.totalmem()</a></li>
<li><a href="#all_os_freemem">os.freemem()</a></li>
<li><a href="#all_os_cpus">os.cpus()</a></li>
<li><a href="#all_os_networkinterfaces">os.networkInterfaces()</a></li>
<li><a href="#all_os_eol">os.EOL</a></li>
</ul>
</li>
<li><a href="#all_debugger">Debugger</a><ul>
<li><a href="#all_watchers">Watchers</a></li>
<li><a href="#all_commands_reference">Commands reference</a><ul>
<li><a href="#all_stepping">Stepping</a></li>
<li><a href="#all_breakpoints">Breakpoints</a></li>
<li><a href="#all_info">Info</a></li>
<li><a href="#all_execution_control">Execution control</a></li>
<li><a href="#all_various">Various</a></li>
</ul>
</li>
<li><a href="#all_advanced_usage">Advanced Usage</a></li>
</ul>
</li>
<li><a href="#all_cluster">Cluster</a><ul>
<li><a href="#all_how_it_works">How It Works</a></li>
<li><a href="#all_cluster_settings">cluster.settings</a></li>
<li><a href="#all_cluster_ismaster">cluster.isMaster</a></li>
<li><a href="#all_cluster_isworker">cluster.isWorker</a></li>
<li><a href="#all_event_fork">Event: &#39;fork&#39;</a></li>
<li><a href="#all_event_online">Event: &#39;online&#39;</a></li>
<li><a href="#all_event_listening_2">Event: &#39;listening&#39;</a></li>
<li><a href="#all_event_disconnect_1">Event: &#39;disconnect&#39;</a></li>
<li><a href="#all_event_exit_3">Event: &#39;exit&#39;</a></li>
<li><a href="#all_event_setup">Event: &#39;setup&#39;</a></li>
<li><a href="#all_cluster_setupmaster_settings">cluster.setupMaster([settings])</a></li>
<li><a href="#all_cluster_fork_env">cluster.fork([env])</a></li>
<li><a href="#all_cluster_disconnect_callback">cluster.disconnect([callback])</a></li>
<li><a href="#all_cluster_worker">cluster.worker</a></li>
<li><a href="#all_cluster_workers">cluster.workers</a></li>
<li><a href="#all_class_worker">Class: Worker</a><ul>
<li><a href="#all_worker_id">worker.id</a></li>
<li><a href="#all_worker_process">worker.process</a></li>
<li><a href="#all_worker_suicide">worker.suicide</a></li>
<li><a href="#all_worker_send_message_sendhandle">worker.send(message, [sendHandle])</a></li>
<li><a href="#all_worker_kill_signal_sigterm">worker.kill([signal=&#39;SIGTERM&#39;])</a></li>
<li><a href="#all_worker_disconnect">worker.disconnect()</a></li>
<li><a href="#all_event_message_2">Event: &#39;message&#39;</a></li>
<li><a href="#all_event_online_1">Event: &#39;online&#39;</a></li>
<li><a href="#all_event_listening_3">Event: &#39;listening&#39;</a></li>
<li><a href="#all_event_disconnect_2">Event: &#39;disconnect&#39;</a></li>
<li><a href="#all_event_exit_4">Event: &#39;exit&#39;</a></li>
<li><a href="#all_event_error_7">Event: &#39;error&#39;</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
<div id="apicontent">
<h1>About this Documentation<span><a class="mark" href="#all_about_this_documentation" id="all_about_this_documentation">#</a></span></h1>
<!-- type=misc -->
<p>The goal of this documentation is to comprehensively explain the Node.js
API, both from a reference as well as a conceptual point of view. Each
section describes a built-in module or high-level concept.
</p>
<p>Where appropriate, property types, method arguments, and the arguments
provided to event handlers are detailed in a list underneath the topic
heading.
</p>
<p>Every <code>.html</code> document has a corresponding <code>.json</code> document presenting
the same information in a structured manner. This feature is
experimental, and added for the benefit of IDEs and other utilities that
wish to do programmatic things with the documentation.
</p>
<p>Every <code>.html</code> and <code>.json</code> file is generated based on the corresponding
<code>.markdown</code> file in the <code>doc/api/</code> folder in node&#39;s source tree. The
documentation is generated using the <code>tools/doc/generate.js</code> program.
The HTML template is located at <code>doc/template.html</code>.
</p>
<h2>Stability Index<span><a class="mark" href="#all_stability_index" id="all_stability_index">#</a></span></h2>
<!--type=misc-->
<p>Throughout the documentation, you will see indications of a section&#39;s
stability. The Node.js API is still somewhat changing, and as it
matures, certain parts are more reliable than others. Some are so
proven, and so relied upon, that they are unlikely to ever change at
all. Others are brand new and experimental, or known to be hazardous
and in the process of being redesigned.
</p>
<p>The stability indices are as follows:
</p>
<pre class="api_stability_0">Stability: 0 - Deprecated
This feature is known to be problematic, and changes are
planned. Do not rely on it. Use of the feature may cause warnings. Backwards
compatibility should not be expected.</pre><pre class="api_stability_1">Stability: 1 - Experimental
This feature was introduced recently, and may change
or be removed in future versions. Please try it out and provide feedback.
If it addresses a use-case that is important to you, tell the node core team.</pre><pre class="api_stability_2">Stability: 2 - Unstable
The API is in the process of settling, but has not yet had
sufficient real-world testing to be considered stable. Backwards-compatibility
will be maintained if reasonable.</pre><pre class="api_stability_3">Stability: 3 - Stable
The API has proven satisfactory, but cleanup in the underlying
code may cause minor changes. Backwards-compatibility is guaranteed.</pre><pre class="api_stability_4">Stability: 4 - API Frozen
This API has been tested extensively in production and is
unlikely to ever have to change.</pre><pre class="api_stability_5">Stability: 5 - Locked
Unless serious bugs are found, this code will not ever
change. Please do not suggest changes in this area; they will be refused.</pre><h2>JSON Output<span><a class="mark" href="#all_json_output" id="all_json_output">#</a></span></h2>
<pre class="api_stability_1">Stability: 1 - Experimental</pre><p>Every HTML file in the markdown has a corresponding JSON file with the
same data.
</p>
<p>This feature is new as of node v0.6.12. It is experimental.
</p>
<h1>Synopsis<span><a class="mark" href="#all_synopsis" id="all_synopsis">#</a></span></h1>
<!--type=misc-->
<p>An example of a <a href="http.html">web server</a> written with Node which responds with &#39;Hello
World&#39;:
</p>
<pre><code>var http = require(&#39;http&#39;);
http.createServer(function (request, response) {
response.writeHead(200, {&#39;Content-Type&#39;: &#39;text/plain&#39;});
response.end(&#39;Hello World\n&#39;);
}).listen(8124);
console.log(&#39;Server running at http://127.0.0.1:8124/&#39;);</code></pre>
<p>To run the server, put the code into a file called <code>example.js</code> and execute
it with the node program
</p>
<pre><code>&gt; node example.js
Server running at http://127.0.0.1:8124/</code></pre>
<p>All of the examples in the documentation can be run similarly.
</p>
<h1>Global Objects<span><a class="mark" href="#all_global_objects" id="all_global_objects">#</a></span></h1>
<!-- type=misc -->
<p>These objects are available in all modules. Some of these objects aren&#39;t
actually in the global scope but in the module scope - this will be noted.
</p>
<h2>global<span><a class="mark" href="#all_global" id="all_global">#</a></span></h2>
<!-- type=global -->
<ul>
<li>{Object} The global namespace object.</li>
</ul>
<p>In browsers, the top-level scope is the global scope. That means that in
browsers if you&#39;re in the global scope <code>var something</code> will define a global
variable. In Node this is different. The top-level scope is not the global
scope; <code>var something</code> inside a Node module will be local to that module.
</p>
<h2>process<span><a class="mark" href="#all_process" id="all_process">#</a></span></h2>
<!-- type=global -->
<ul>
<li>{Object}</li>
</ul>
<p>The process object. See the <a href="process.html#process_process">process object</a> section.
</p>
<h2>console<span><a class="mark" href="#all_console" id="all_console">#</a></span></h2>
<!-- type=global -->
<ul>
<li>{Object}</li>
</ul>
<p>Used to print to stdout and stderr. See the <a href="console.html">console</a> section.
</p>
<h2>Class: Buffer<span><a class="mark" href="#all_class_buffer" id="all_class_buffer">#</a></span></h2>
<!-- type=global -->
<ul>
<li>{Function}</li>
</ul>
<p>Used to handle binary data. See the <a href="buffer.html">buffer section</a>
</p>
<h2>require()<span><a class="mark" href="#all_require" id="all_require">#</a></span></h2>
<!-- type=var -->
<ul>
<li>{Function}</li>
</ul>
<p>To require modules. See the <a href="modules.html#modules_modules">Modules</a> section. <code>require</code> isn&#39;t actually a
global but rather local to each module.
</p>
<h3>require.resolve()<span><a class="mark" href="#all_require_resolve" id="all_require_resolve">#</a></span></h3>
<p>Use the internal <code>require()</code> machinery to look up the location of a module,
but rather than loading the module, just return the resolved filename.
</p>
<h3>require.cache<span><a class="mark" href="#all_require_cache" id="all_require_cache">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<p>Modules are cached in this object when they are required. By deleting a key
value from this object, the next <code>require</code> will reload the module.
</p>
<h3>require.extensions<span><a class="mark" href="#all_require_extensions" id="all_require_extensions">#</a></span></h3>
<pre class="api_stability_0">Stability: 0 - Deprecated</pre><div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<p>Instruct <code>require</code> on how to handle certain file extensions.
</p>
<p>Process files with the extension <code>.sjs</code> as <code>.js</code>:
</p>
<pre><code>require.extensions[&#39;.sjs&#39;] = require.extensions[&#39;.js&#39;];</code></pre>
<p><strong>Deprecated</strong> In the past, this list has been used to load
non-JavaScript modules into Node by compiling them on-demand.
However, in practice, there are much better ways to do this, such as
loading modules via some other Node program, or compiling them to
JavaScript ahead of time.
</p>
<p>Since the Module system is locked, this feature will probably never go
away. However, it may have subtle bugs and complexities that are best
left untouched.
</p>
<h2>__filename<span><a class="mark" href="#all_filename" id="all_filename">#</a></span></h2>
<!-- type=var -->
<ul>
<li>{String}</li>
</ul>
<p>The filename of the code being executed. This is the resolved absolute path
of this code file. For a main program this is not necessarily the same
filename used in the command line. The value inside a module is the path
to that module file.
</p>
<p>Example: running <code>node example.js</code> from <code>/Users/mjr</code>
</p>
<pre><code>console.log(__filename);
// /Users/mjr/example.js</code></pre>
<p><code>__filename</code> isn&#39;t actually a global but rather local to each module.
</p>
<h2>__dirname<span><a class="mark" href="#all_dirname" id="all_dirname">#</a></span></h2>
<!-- type=var -->
<ul>
<li>{String}</li>
</ul>
<p>The name of the directory that the currently executing script resides in.
</p>
<p>Example: running <code>node example.js</code> from <code>/Users/mjr</code>
</p>
<pre><code>console.log(__dirname);
// /Users/mjr</code></pre>
<p><code>__dirname</code> isn&#39;t actually a global but rather local to each module.
</p>
<h2>module<span><a class="mark" href="#all_module" id="all_module">#</a></span></h2>
<!-- type=var -->
<ul>
<li>{Object}</li>
</ul>
<p>A reference to the current module. In particular
<code>module.exports</code> is used for defining what a module exports and makes
available through <code>require()</code>.
</p>
<p><code>module</code> isn&#39;t actually a global but rather local to each module.
</p>
<p>See the <a href="modules.html">module system documentation</a> for more information.
</p>
<h2>exports<span><a class="mark" href="#all_exports" id="all_exports">#</a></span></h2>
<!-- type=var -->
<p>A reference to the <code>module.exports</code> that is shorter to type.
See <a href="modules.html">module system documentation</a> for details on when to use <code>exports</code> and
when to use <code>module.exports</code>.
</p>
<p><code>exports</code> isn&#39;t actually a global but rather local to each module.
</p>
<p>See the <a href="modules.html">module system documentation</a> for more information.
</p>
<p>See the <a href="modules.html">module section</a> for more information.
</p>
<h2>setTimeout(cb, ms)<span><a class="mark" href="#all_settimeout_cb_ms" id="all_settimeout_cb_ms">#</a></span></h2>
<p>Run callback <code>cb</code> after <em>at least</em> <code>ms</code> milliseconds. The actual delay depends
on external factors like OS timer granularity and system load.
</p>
<p>The timeout must be in the range of 1-2,147,483,647 inclusive. If the value is
outside that range, it&#39;s changed to 1 millisecond. Broadly speaking, a timer
cannot span more than 24.8 days.
</p>
<p>Returns an opaque value that represents the timer.
</p>
<h2>clearTimeout(t)<span><a class="mark" href="#all_cleartimeout_t" id="all_cleartimeout_t">#</a></span></h2>
<p>Stop a timer that was previously created with <code>setTimeout()</code>. The callback will
not execute.
</p>
<h2>setInterval(cb, ms)<span><a class="mark" href="#all_setinterval_cb_ms" id="all_setinterval_cb_ms">#</a></span></h2>
<p>Run callback <code>cb</code> repeatedly every <code>ms</code> milliseconds. Note that the actual
interval may vary, depending on external factors like OS timer granularity and
system load. It&#39;s never less than <code>ms</code> but it may be longer.
</p>
<p>The interval must be in the range of 1-2,147,483,647 inclusive. If the value is
outside that range, it&#39;s changed to 1 millisecond. Broadly speaking, a timer
cannot span more than 24.8 days.
</p>
<p>Returns an opaque value that represents the timer.
</p>
<h2>clearInterval(t)<span><a class="mark" href="#all_clearinterval_t" id="all_clearinterval_t">#</a></span></h2>
<p>Stop a timer that was previously created with <code>setInterval()</code>. The callback
will not execute.
</p>
<!--type=global-->
<p>The timer functions are global variables. See the <a href="timers.html">timers</a> section.
</p>
<h1>console<span><a class="mark" href="#all_console_1" id="all_console_1">#</a></span></h1>
<pre class="api_stability_4">Stability: 4 - API Frozen</pre><div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<!--type=global-->
<p>For printing to stdout and stderr. Similar to the console object functions
provided by most web browsers, here the output is sent to stdout or stderr.
</p>
<p>The console functions are synchronous when the destination is a terminal or
a file (to avoid lost messages in case of premature exit) and asynchronous
when it&#39;s a pipe (to avoid blocking for long periods of time).
</p>
<p>That is, in the following example, stdout is non-blocking while stderr
is blocking:
</p>
<pre><code>$ node script.js 2&gt; error.log | tee info.log</code></pre>
<p>In daily use, the blocking/non-blocking dichotomy is not something you
should worry about unless you log huge amounts of data.
</p>
<h2>console.log([data], [...])<span><a class="mark" href="#all_console_log_data" id="all_console_log_data">#</a></span></h2>
<p>Prints to stdout with newline. This function can take multiple arguments in a
<code>printf()</code>-like way. Example:
</p>
<pre><code>console.log(&#39;count: %d&#39;, count);</code></pre>
<p>If formatting elements are not found in the first string then <code>util.inspect</code>
is used on each argument. See <a href="util.html#util_util_format_format">util.format()</a> for more information.
</p>
<h2>console.info([data], [...])<span><a class="mark" href="#all_console_info_data" id="all_console_info_data">#</a></span></h2>
<p>Same as <code>console.log</code>.
</p>
<h2>console.error([data], [...])<span><a class="mark" href="#all_console_error_data" id="all_console_error_data">#</a></span></h2>
<p>Same as <code>console.log</code> but prints to stderr.
</p>
<h2>console.warn([data], [...])<span><a class="mark" href="#all_console_warn_data" id="all_console_warn_data">#</a></span></h2>
<p>Same as <code>console.error</code>.
</p>
<h2>console.dir(obj)<span><a class="mark" href="#all_console_dir_obj" id="all_console_dir_obj">#</a></span></h2>
<p>Uses <code>util.inspect</code> on <code>obj</code> and prints resulting string to stdout.
</p>
<h2>console.time(label)<span><a class="mark" href="#all_console_time_label" id="all_console_time_label">#</a></span></h2>
<p>Mark a time.
</p>
<h2>console.timeEnd(label)<span><a class="mark" href="#all_console_timeend_label" id="all_console_timeend_label">#</a></span></h2>
<p>Finish timer, record output. Example:
</p>
<pre><code>console.time(&#39;100-elements&#39;);
for (var i = 0; i &lt; 100; i++) {
;
}
console.timeEnd(&#39;100-elements&#39;);</code></pre>
<h2>console.trace(label)<span><a class="mark" href="#all_console_trace_label" id="all_console_trace_label">#</a></span></h2>
<p>Print a stack trace to stderr of the current position.
</p>
<h2>console.assert(expression, [message])<span><a class="mark" href="#all_console_assert_expression_message" id="all_console_assert_expression_message">#</a></span></h2>
<p>Same as <a href="assert.html#assert_assert_value_message_assert_ok_value_message">assert.ok()</a> where if the <code>expression</code> evaluates as <code>false</code> throw an
AssertionError with <code>message</code>.
</p>
<h1>Timers<span><a class="mark" href="#all_timers" id="all_timers">#</a></span></h1>
<pre class="api_stability_5">Stability: 5 - Locked</pre><p>All of the timer functions are globals. You do not need to <code>require()</code>
this module in order to use them.
</p>
<h2>setTimeout(callback, delay, [arg], [...])<span><a class="mark" href="#all_settimeout_callback_delay_arg" id="all_settimeout_callback_delay_arg">#</a></span></h2>
<p>To schedule execution of a one-time <code>callback</code> after <code>delay</code> milliseconds. Returns a
<code>timeoutId</code> for possible use with <code>clearTimeout()</code>. Optionally you can
also pass arguments to the callback.
</p>
<p>It is important to note that your callback will probably not be called in exactly
<code>delay</code> milliseconds - Node.js makes no guarantees about the exact timing of when
the callback will fire, nor of the ordering things will fire in. The callback will
be called as close as possible to the time specified.
</p>
<h2>clearTimeout(timeoutId)<span><a class="mark" href="#all_cleartimeout_timeoutid" id="all_cleartimeout_timeoutid">#</a></span></h2>
<p>Prevents a timeout from triggering.
</p>
<h2>setInterval(callback, delay, [arg], [...])<span><a class="mark" href="#all_setinterval_callback_delay_arg" id="all_setinterval_callback_delay_arg">#</a></span></h2>
<p>To schedule the repeated execution of <code>callback</code> every <code>delay</code> milliseconds.
Returns a <code>intervalId</code> for possible use with <code>clearInterval()</code>. Optionally
you can also pass arguments to the callback.
</p>
<h2>clearInterval(intervalId)<span><a class="mark" href="#all_clearinterval_intervalid" id="all_clearinterval_intervalid">#</a></span></h2>
<p>Stops a interval from triggering.
</p>
<h2>unref()<span><a class="mark" href="#all_unref" id="all_unref">#</a></span></h2>
<p>The opaque value returned by <code>setTimeout</code> and <code>setInterval</code> also has the method
<code>timer.unref()</code> which will allow you to create a timer that is active but if
it is the only item left in the event loop won&#39;t keep the program running.
If the timer is already <code>unref</code>d calling <code>unref</code> again will have no effect.
</p>
<p>In the case of <code>setTimeout</code> when you <code>unref</code> you create a separate timer that
will wakeup the event loop, creating too many of these may adversely effect
event loop performance -- use wisely.
</p>
<h2>ref()<span><a class="mark" href="#all_ref" id="all_ref">#</a></span></h2>
<p>If you had previously <code>unref()</code>d a timer you can call <code>ref()</code> to explicitly
request the timer hold the program open. If the timer is already <code>ref</code>d calling
<code>ref</code> again will have no effect.
</p>
<h2>setImmediate(callback, [arg], [...])<span><a class="mark" href="#all_setimmediate_callback_arg" id="all_setimmediate_callback_arg">#</a></span></h2>
<p>To schedule the &quot;immediate&quot; execution of <code>callback</code> after I/O events
callbacks and before <code>setTimeout</code> and <code>setInterval</code> . Returns an
<code>immediateId</code> for possible use with <code>clearImmediate()</code>. Optionally you
can also pass arguments to the callback.
</p>
<p>Immediates are queued in the order created, and are popped off the queue once
per loop iteration. This is different from <code>process.nextTick</code> which will
execute <code>process.maxTickDepth</code> queued callbacks per iteration. <code>setImmediate</code>
will yield to the event loop after firing a queued callback to make sure I/O is
not being starved. While order is preserved for execution, other I/O events may
fire between any two scheduled immediate callbacks.
</p>
<h2>clearImmediate(immediateId)<span><a class="mark" href="#all_clearimmediate_immediateid" id="all_clearimmediate_immediateid">#</a></span></h2>
<p>Stops an immediate from triggering.
</p>
<h1>Modules<span><a class="mark" href="#all_modules" id="all_modules">#</a></span></h1>
<pre class="api_stability_5">Stability: 5 - Locked</pre><!--name=module-->
<p>Node has a simple module loading system. In Node, files and modules are in
one-to-one correspondence. As an example, <code>foo.js</code> loads the module
<code>circle.js</code> in the same directory.
</p>
<p>The contents of <code>foo.js</code>:
</p>
<pre><code>var circle = require(&#39;./circle.js&#39;);
console.log( &#39;The area of a circle of radius 4 is &#39;
+ circle.area(4));</code></pre>
<p>The contents of <code>circle.js</code>:
</p>
<pre><code>var PI = Math.PI;
exports.area = function (r) {
return PI * r * r;
};
exports.circumference = function (r) {
return 2 * PI * r;
};</code></pre>
<p>The module <code>circle.js</code> has exported the functions <code>area()</code> and
<code>circumference()</code>. To add functions and objects to the root of your module,
you can add them to the special <code>exports</code> object.
</p>
<p>Variables local to the module will be private, as though the module was wrapped
in a function. In this example the variable <code>PI</code> is private to <code>circle.js</code>.
</p>
<p>If you want the root of your module&#39;s export to be a function (such as a
constructor) or if you want to export a complete object in one assignment
instead of building it one property at a time, assign it to <code>module.exports</code>
instead of <code>exports</code>.
</p>
<p>Below, <code>bar.js</code> makes use of the <code>square</code> module, which exports a constructor:
</p>
<pre><code>var square = require(&#39;./square.js&#39;);
var mySquare = square(2);
console.log(&#39;The area of my square is &#39; + mySquare.area());</code></pre>
<p>The <code>square</code> module is defined in <code>square.js</code>:
</p>
<pre><code>// assigning to exports will not modify module, must use module.exports
module.exports = function(width) {
return {
area: function() {
return width * width;
}
};
}</code></pre>
<p>The module system is implemented in the <code>require(&quot;module&quot;)</code> module.
</p>
<h2>Cycles<span><a class="mark" href="#all_cycles" id="all_cycles">#</a></span></h2>
<!--type=misc-->
<p>When there are circular <code>require()</code> calls, a module might not be
done being executed when it is returned.
</p>
<p>Consider this situation:
</p>
<p><code>a.js</code>:
</p>
<pre><code>console.log(&#39;a starting&#39;);
exports.done = false;
var b = require(&#39;./b.js&#39;);
console.log(&#39;in a, b.done = %j&#39;, b.done);
exports.done = true;
console.log(&#39;a done&#39;);</code></pre>
<p><code>b.js</code>:
</p>
<pre><code>console.log(&#39;b starting&#39;);
exports.done = false;
var a = require(&#39;./a.js&#39;);
console.log(&#39;in b, a.done = %j&#39;, a.done);
exports.done = true;
console.log(&#39;b done&#39;);</code></pre>
<p><code>main.js</code>:
</p>
<pre><code>console.log(&#39;main starting&#39;);
var a = require(&#39;./a.js&#39;);
var b = require(&#39;./b.js&#39;);
console.log(&#39;in main, a.done=%j, b.done=%j&#39;, a.done, b.done);</code></pre>
<p>When <code>main.js</code> loads <code>a.js</code>, then <code>a.js</code> in turn loads <code>b.js</code>. At that
point, <code>b.js</code> tries to load <code>a.js</code>. In order to prevent an infinite
loop an <strong>unfinished copy</strong> of the <code>a.js</code> exports object is returned to the
<code>b.js</code> module. <code>b.js</code> then finishes loading, and its <code>exports</code> object is
provided to the <code>a.js</code> module.
</p>
<p>By the time <code>main.js</code> has loaded both modules, they&#39;re both finished.
The output of this program would thus be:
</p>
<pre><code>$ node main.js
main starting
a starting
b starting
in b, a.done = false
b done
in a, b.done = true
a done
in main, a.done=true, b.done=true</code></pre>
<p>If you have cyclic module dependencies in your program, make sure to
plan accordingly.
</p>
<h2>Core Modules<span><a class="mark" href="#all_core_modules" id="all_core_modules">#</a></span></h2>
<!--type=misc-->
<p>Node has several modules compiled into the binary. These modules are
described in greater detail elsewhere in this documentation.
</p>
<p>The core modules are defined in node&#39;s source in the <code>lib/</code> folder.
</p>
<p>Core modules are always preferentially loaded if their identifier is
passed to <code>require()</code>. For instance, <code>require(&#39;http&#39;)</code> will always
return the built in HTTP module, even if there is a file by that name.
</p>
<h2>File Modules<span><a class="mark" href="#all_file_modules" id="all_file_modules">#</a></span></h2>
<!--type=misc-->
<p>If the exact filename is not found, then node will attempt to load the
required filename with the added extension of <code>.js</code>, <code>.json</code>, and then <code>.node</code>.
</p>
<p><code>.js</code> files are interpreted as JavaScript text files, and <code>.json</code> files are
parsed as JSON text files. <code>.node</code> files are interpreted as compiled addon
modules loaded with <code>dlopen</code>.
</p>
<p>A module prefixed with <code>&#39;/&#39;</code> is an absolute path to the file. For
example, <code>require(&#39;/home/marco/foo.js&#39;)</code> will load the file at
<code>/home/marco/foo.js</code>.
</p>
<p>A module prefixed with <code>&#39;./&#39;</code> is relative to the file calling <code>require()</code>.
That is, <code>circle.js</code> must be in the same directory as <code>foo.js</code> for
<code>require(&#39;./circle&#39;)</code> to find it.
</p>
<p>Without a leading &#39;/&#39; or &#39;./&#39; to indicate a file, the module is either a
&quot;core module&quot; or is loaded from a <code>node_modules</code> folder.
</p>
<p>If the given path does not exist, <code>require()</code> will throw an Error with its
<code>code</code> property set to <code>&#39;MODULE_NOT_FOUND&#39;</code>.
</p>
<h2>Loading from <code>node_modules</code> Folders<span><a class="mark" href="#all_loading_from_node_modules_folders" id="all_loading_from_node_modules_folders">#</a></span></h2>
<!--type=misc-->
<p>If the module identifier passed to <code>require()</code> is not a native module,
and does not begin with <code>&#39;/&#39;</code>, <code>&#39;../&#39;</code>, or <code>&#39;./&#39;</code>, then node starts at the
parent directory of the current module, and adds <code>/node_modules</code>, and
attempts to load the module from that location.
</p>
<p>If it is not found there, then it moves to the parent directory, and so
on, until the root of the tree is reached.
</p>
<p>For example, if the file at <code>&#39;/home/ry/projects/foo.js&#39;</code> called
<code>require(&#39;bar.js&#39;)</code>, then node would look in the following locations, in
this order:
</p>
<ul>
<li><code>/home/ry/projects/node_modules/bar.js</code></li>
<li><code>/home/ry/node_modules/bar.js</code></li>
<li><code>/home/node_modules/bar.js</code></li>
<li><code>/node_modules/bar.js</code></li>
</ul>
<p>This allows programs to localize their dependencies, so that they do not
clash.
</p>
<h2>Folders as Modules<span><a class="mark" href="#all_folders_as_modules" id="all_folders_as_modules">#</a></span></h2>
<!--type=misc-->
<p>It is convenient to organize programs and libraries into self-contained
directories, and then provide a single entry point to that library.
There are three ways in which a folder may be passed to <code>require()</code> as
an argument.
</p>
<p>The first is to create a <code>package.json</code> file in the root of the folder,
which specifies a <code>main</code> module. An example package.json file might
look like this:
</p>
<pre><code>{ &quot;name&quot; : &quot;some-library&quot;,
&quot;main&quot; : &quot;./lib/some-library.js&quot; }</code></pre>
<p>If this was in a folder at <code>./some-library</code>, then
<code>require(&#39;./some-library&#39;)</code> would attempt to load
<code>./some-library/lib/some-library.js</code>.
</p>
<p>This is the extent of Node&#39;s awareness of package.json files.
</p>
<p>If there is no package.json file present in the directory, then node
will attempt to load an <code>index.js</code> or <code>index.node</code> file out of that
directory. For example, if there was no package.json file in the above
example, then <code>require(&#39;./some-library&#39;)</code> would attempt to load:
</p>
<ul>
<li><code>./some-library/index.js</code></li>
<li><code>./some-library/index.node</code></li>
</ul>
<h2>Caching<span><a class="mark" href="#all_caching" id="all_caching">#</a></span></h2>
<!--type=misc-->
<p>Modules are cached after the first time they are loaded. This means
(among other things) that every call to <code>require(&#39;foo&#39;)</code> will get
exactly the same object returned, if it would resolve to the same file.
</p>
<p>Multiple calls to <code>require(&#39;foo&#39;)</code> may not cause the module code to be
executed multiple times. This is an important feature. With it,
&quot;partially done&quot; objects can be returned, thus allowing transitive
dependencies to be loaded even when they would cause cycles.
</p>
<p>If you want to have a module execute code multiple times, then export a
function, and call that function.
</p>
<h3>Module Caching Caveats<span><a class="mark" href="#all_module_caching_caveats" id="all_module_caching_caveats">#</a></span></h3>
<!--type=misc-->
<p>Modules are cached based on their resolved filename. Since modules may
resolve to a different filename based on the location of the calling
module (loading from <code>node_modules</code> folders), it is not a <em>guarantee</em>
that <code>require(&#39;foo&#39;)</code> will always return the exact same object, if it
would resolve to different files.
</p>
<h2>The <code>module</code> Object<span><a class="mark" href="#all_the_module_object" id="all_the_module_object">#</a></span></h2>
<!-- type=var -->
<!-- name=module -->
<ul>
<li>{Object}</li>
</ul>
<p>In each module, the <code>module</code> free variable is a reference to the object
representing the current module. For convenience, <code>module.exports</code> is
also accessible via the <code>exports</code> module-global. <code>module</code> isn&#39;t actually
a global but rather local to each module.
</p>
<h3>module.exports<span><a class="mark" href="#all_module_exports" id="all_module_exports">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<p>The <code>module.exports</code> object is created by the Module system. Sometimes this is not
acceptable; many want their module to be an instance of some class. To do this
assign the desired export object to <code>module.exports</code>. Note that assigning the
desired object to <code>exports</code> will simply rebind the local <code>exports</code> variable,
which is probably not what you want to do.
</p>
<p>For example suppose we were making a module called <code>a.js</code>
</p>
<pre><code>var EventEmitter = require(&#39;events&#39;).EventEmitter;
module.exports = new EventEmitter();
// Do some work, and after some time emit
// the &#39;ready&#39; event from the module itself.
setTimeout(function() {
module.exports.emit(&#39;ready&#39;);
}, 1000);</code></pre>
<p>Then in another file we could do
</p>
<pre><code>var a = require(&#39;./a&#39;);
a.on(&#39;ready&#39;, function() {
console.log(&#39;module a is ready&#39;);
});</code></pre>
<p>Note that assignment to <code>module.exports</code> must be done immediately. It cannot be
done in any callbacks. This does not work:
</p>
<p>x.js:
</p>
<pre><code>setTimeout(function() {
module.exports = { a: &quot;hello&quot; };
}, 0);</code></pre>
<p>y.js:
</p>
<pre><code>var x = require(&#39;./x&#39;);
console.log(x.a);</code></pre>
<h4>exports alias<span><a class="mark" href="#all_exports_alias" id="all_exports_alias">#</a></span></h4>
<p>The <code>exports</code> variable that is available within a module starts as a reference
to <code>module.exports</code>. As with any variable, if you assign a new value to it, it
is no longer bound to the previous value.
</p>
<p>To illustrate the behaviour, imagine this hypothetical implementation of
<code>require()</code>:
</p>
<pre><code>function require(...) {
// ...
function (module, exports) {
// Your module code here
exports = some_func; // re-assigns exports, exports is no longer
// a shortcut, and nothing is exported.
module.exports = some_func; // makes your module export 0
} (module, module.exports);
return module;
}</code></pre>
<p>As a guideline, if the relationship between <code>exports</code> and <code>module.exports</code>
seems like magic to you, ignore <code>exports</code> and only use <code>module.exports</code>.
</p>
<h3>module.require(id)<span><a class="mark" href="#all_module_require_id" id="all_module_require_id">#</a></span></h3>
<div class="signature"><ul>
<li><code>id</code> <span class="type">String</span></li>
<li>Return: <span class="type">Object</span> <code>module.exports</code> from the resolved module</li>
</div></ul>
<p>The <code>module.require</code> method provides a way to load a module as if
<code>require()</code> was called from the original module.
</p>
<p>Note that in order to do this, you must get a reference to the <code>module</code>
object. Since <code>require()</code> returns the <code>module.exports</code>, and the <code>module</code> is
typically <em>only</em> available within a specific module&#39;s code, it must be
explicitly exported in order to be used.
</p>
<h3>module.id<span><a class="mark" href="#all_module_id" id="all_module_id">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">String</span></li>
</div></ul>
<p>The identifier for the module. Typically this is the fully resolved
filename.
</p>
<h3>module.filename<span><a class="mark" href="#all_module_filename" id="all_module_filename">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">String</span></li>
</div></ul>
<p>The fully resolved filename to the module.
</p>
<h3>module.loaded<span><a class="mark" href="#all_module_loaded" id="all_module_loaded">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Boolean</span></li>
</div></ul>
<p>Whether or not the module is done loading, or is in the process of
loading.
</p>
<h3>module.parent<span><a class="mark" href="#all_module_parent" id="all_module_parent">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Module Object</span></li>
</div></ul>
<p>The module that required this one.
</p>
<h3>module.children<span><a class="mark" href="#all_module_children" id="all_module_children">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Array</span></li>
</div></ul>
<p>The module objects required by this one.
</p>
<h2>All Together...<span><a class="mark" href="#all_all_together" id="all_all_together">#</a></span></h2>
<!-- type=misc -->
<p>To get the exact filename that will be loaded when <code>require()</code> is called, use
the <code>require.resolve()</code> function.
</p>
<p>Putting together all of the above, here is the high-level algorithm
in pseudocode of what require.resolve does:
</p>
<pre><code>require(X) from module at path Y
1. If X is a core module,
a. return the core module
b. STOP
2. If X begins with &#39;./&#39; or &#39;/&#39; or &#39;../&#39;
a. LOAD_AS_FILE(Y + X)
b. LOAD_AS_DIRECTORY(Y + X)
3. LOAD_NODE_MODULES(X, dirname(Y))
4. THROW &quot;not found&quot;
LOAD_AS_FILE(X)
1. If X is a file, load X as JavaScript text. STOP
2. If X.js is a file, load X.js as JavaScript text. STOP
3. If X.node is a file, load X.node as binary addon. STOP
LOAD_AS_DIRECTORY(X)
1. If X/package.json is a file,
a. Parse X/package.json, and look for &quot;main&quot; field.
b. let M = X + (json main field)
c. LOAD_AS_FILE(M)
2. If X/index.js is a file, load X/index.js as JavaScript text. STOP
3. If X/index.node is a file, load X/index.node as binary addon. STOP
LOAD_NODE_MODULES(X, START)
1. let DIRS=NODE_MODULES_PATHS(START)
2. for each DIR in DIRS:
a. LOAD_AS_FILE(DIR/X)
b. LOAD_AS_DIRECTORY(DIR/X)
NODE_MODULES_PATHS(START)
1. let PARTS = path split(START)
2. let ROOT = index of first instance of &quot;node_modules&quot; in PARTS, or 0
3. let I = count of PARTS - 1
4. let DIRS = []
5. while I &gt; ROOT,
a. if PARTS[I] = &quot;node_modules&quot; CONTINUE
c. DIR = path join(PARTS[0 .. I] + &quot;node_modules&quot;)
b. DIRS = DIRS + DIR
c. let I = I - 1
6. return DIRS</code></pre>
<h2>Loading from the global folders<span><a class="mark" href="#all_loading_from_the_global_folders" id="all_loading_from_the_global_folders">#</a></span></h2>
<!-- type=misc -->
<p>If the <code>NODE_PATH</code> environment variable is set to a colon-delimited list
of absolute paths, then node will search those paths for modules if they
are not found elsewhere. (Note: On Windows, <code>NODE_PATH</code> is delimited by
semicolons instead of colons.)
</p>
<p>Additionally, node will search in the following locations:
</p>
<ul>
<li>1: <code>$HOME/.node_modules</code></li>
<li>2: <code>$HOME/.node_libraries</code></li>
<li>3: <code>$PREFIX/lib/node</code></li>
</ul>
<p>Where <code>$HOME</code> is the user&#39;s home directory, and <code>$PREFIX</code> is node&#39;s
configured <code>node_prefix</code>.
</p>
<p>These are mostly for historic reasons. You are highly encouraged to
place your dependencies locally in <code>node_modules</code> folders. They will be
loaded faster, and more reliably.
</p>
<h2>Accessing the main module<span><a class="mark" href="#all_accessing_the_main_module" id="all_accessing_the_main_module">#</a></span></h2>
<!-- type=misc -->
<p>When a file is run directly from Node, <code>require.main</code> is set to its
<code>module</code>. That means that you can determine whether a file has been run
directly by testing
</p>
<pre><code>require.main === module</code></pre>
<p>For a file <code>foo.js</code>, this will be <code>true</code> if run via <code>node foo.js</code>, but
<code>false</code> if run by <code>require(&#39;./foo&#39;)</code>.
</p>
<p>Because <code>module</code> provides a <code>filename</code> property (normally equivalent to
<code>__filename</code>), the entry point of the current application can be obtained
by checking <code>require.main.filename</code>.
</p>
<h2>Addenda: Package Manager Tips<span><a class="mark" href="#all_addenda_package_manager_tips" id="all_addenda_package_manager_tips">#</a></span></h2>
<!-- type=misc -->
<p>The semantics of Node&#39;s <code>require()</code> function were designed to be general
enough to support a number of sane directory structures. Package manager
programs such as <code>dpkg</code>, <code>rpm</code>, and <code>npm</code> will hopefully find it possible to
build native packages from Node modules without modification.
</p>
<p>Below we give a suggested directory structure that could work:
</p>
<p>Let&#39;s say that we wanted to have the folder at
<code>/usr/lib/node/&lt;some-package&gt;/&lt;some-version&gt;</code> hold the contents of a
specific version of a package.
</p>
<p>Packages can depend on one another. In order to install package <code>foo</code>, you
may have to install a specific version of package <code>bar</code>. The <code>bar</code> package
may itself have dependencies, and in some cases, these dependencies may even
collide or form cycles.
</p>
<p>Since Node looks up the <code>realpath</code> of any modules it loads (that is,
resolves symlinks), and then looks for their dependencies in the
<code>node_modules</code> folders as described above, this situation is very simple to
resolve with the following architecture:
</p>
<ul>
<li><code>/usr/lib/node/foo/1.2.3/</code> - Contents of the <code>foo</code> package, version 1.2.3.</li>
<li><code>/usr/lib/node/bar/4.3.2/</code> - Contents of the <code>bar</code> package that <code>foo</code>
depends on.</li>
<li><code>/usr/lib/node/foo/1.2.3/node_modules/bar</code> - Symbolic link to
<code>/usr/lib/node/bar/4.3.2/</code>.</li>
<li><code>/usr/lib/node/bar/4.3.2/node_modules/*</code> - Symbolic links to the packages
that <code>bar</code> depends on.</li>
</ul>
<p>Thus, even if a cycle is encountered, or if there are dependency
conflicts, every module will be able to get a version of its dependency
that it can use.
</p>
<p>When the code in the <code>foo</code> package does <code>require(&#39;bar&#39;)</code>, it will get the
version that is symlinked into <code>/usr/lib/node/foo/1.2.3/node_modules/bar</code>.
Then, when the code in the <code>bar</code> package calls <code>require(&#39;quux&#39;)</code>, it&#39;ll get
the version that is symlinked into
<code>/usr/lib/node/bar/4.3.2/node_modules/quux</code>.
</p>
<p>Furthermore, to make the module lookup process even more optimal, rather
than putting packages directly in <code>/usr/lib/node</code>, we could put them in
<code>/usr/lib/node_modules/&lt;name&gt;/&lt;version&gt;</code>. Then node will not bother
looking for missing dependencies in <code>/usr/node_modules</code> or <code>/node_modules</code>.
</p>
<p>In order to make modules available to the node REPL, it might be useful to
also add the <code>/usr/lib/node_modules</code> folder to the <code>$NODE_PATH</code> environment
variable. Since the module lookups using <code>node_modules</code> folders are all
relative, and based on the real path of the files making the calls to
<code>require()</code>, the packages themselves can be anywhere.
</p>
<h1>Addons<span><a class="mark" href="#all_addons" id="all_addons">#</a></span></h1>
<p>Addons are dynamically linked shared objects. They can provide glue to C and
C++ libraries. The API (at the moment) is rather complex, involving
knowledge of several libraries:
</p>
<ul>
<li><p>V8 JavaScript, a C++ library. Used for interfacing with JavaScript:
creating objects, calling functions, etc. Documented mostly in the
<code>v8.h</code> header file (<code>deps/v8/include/v8.h</code> in the Node source
tree), which is also available
<a href="http://izs.me/v8-docs/main.html">online</a>.</p>
</li>
<li><p><a href="https://github.com/joyent/libuv">libuv</a>, C event loop library.
Anytime one needs to wait for a file descriptor to become readable,
wait for a timer, or wait for a signal to be received one will need
to interface with libuv. That is, if you perform any I/O, libuv will
need to be used.</p>
</li>
<li><p>Internal Node libraries. Most importantly is the <code>node::ObjectWrap</code>
class which you will likely want to derive from.</p>
</li>
<li><p>Others. Look in <code>deps/</code> for what else is available.</p>
</li>
</ul>
<p>Node statically compiles all its dependencies into the executable.
When compiling your module, you don&#39;t need to worry about linking to
any of these libraries.
</p>
<p>All of the following examples are available for
<a href="https://github.com/rvagg/node-addon-examples">download</a> and may be
used as a starting-point for your own Addon.
</p>
<h2>Hello world<span><a class="mark" href="#all_hello_world" id="all_hello_world">#</a></span></h2>
<p>To get started let&#39;s make a small Addon which is the C++ equivalent of
the following JavaScript code:
</p>
<pre><code>module.exports.hello = function() { return &#39;world&#39;; };</code></pre>
<p>First we create a file <code>hello.cc</code>:
</p>
<pre><code>#include &lt;node.h&gt;
#include &lt;v8.h&gt;
using namespace v8;
Handle&lt;Value&gt; Method(const Arguments&amp; args) {
HandleScope scope;
return scope.Close(String::New(&quot;world&quot;));
}
void init(Handle&lt;Object&gt; exports) {
exports-&gt;Set(String::NewSymbol(&quot;hello&quot;),
FunctionTemplate::New(Method)-&gt;GetFunction());
}
NODE_MODULE(hello, init)</code></pre>
<p>Note that all Node addons must export an initialization function:
</p>
<pre><code>void Initialize (Handle&lt;Object&gt; exports);
NODE_MODULE(module_name, Initialize)</code></pre>
<p>There is no semi-colon after <code>NODE_MODULE</code> as it&#39;s not a function (see <code>node.h</code>).
</p>
<p>The <code>module_name</code> needs to match the filename of the final binary (minus the
.node suffix).
</p>
<p>The source code needs to be built into <code>hello.node</code>, the binary Addon. To
do this we create a file called <code>binding.gyp</code> which describes the configuration
to build your module in a JSON-like format. This file gets compiled by
<a href="https://github.com/TooTallNate/node-gyp">node-gyp</a>.
</p>
<pre><code>{
&quot;targets&quot;: [
{
&quot;target_name&quot;: &quot;hello&quot;,
&quot;sources&quot;: [ &quot;hello.cc&quot; ]
}
]
}</code></pre>
<p>The next step is to generate the appropriate project build files for the
current platform. Use <code>node-gyp configure</code> for that.
</p>
<p>Now you will have either a <code>Makefile</code> (on Unix platforms) or a <code>vcxproj</code> file
(on Windows) in the <code>build/</code> directory. Next invoke the <code>node-gyp build</code>
command.
</p>
<p>Now you have your compiled <code>.node</code> bindings file! The compiled bindings end up
in <code>build/Release/</code>.
</p>
<p>You can now use the binary addon in a Node project <code>hello.js</code> by pointing <code>require</code> to
the recently built <code>hello.node</code> module:
</p>
<pre><code>var addon = require(&#39;./build/Release/hello&#39;);
console.log(addon.hello()); // &#39;world&#39;</code></pre>
<p>Please see patterns below for further information or
</p>
<p><a href="https://github.com/arturadib/node-qt">https://github.com/arturadib/node-qt</a> for an example in production.
</p>
<h2>Addon patterns<span><a class="mark" href="#all_addon_patterns" id="all_addon_patterns">#</a></span></h2>
<p>Below are some addon patterns to help you get started. Consult the online
<a href="http://izs.me/v8-docs/main.html">v8 reference</a> for help with the various v8
calls, and v8&#39;s <a href="http://code.google.com/apis/v8/embed.html">Embedder&#39;s Guide</a>
for an explanation of several concepts used such as handles, scopes,
function templates, etc.
</p>
<p>In order to use these examples you need to compile them using <code>node-gyp</code>.
Create the following <code>binding.gyp</code> file:
</p>
<pre><code>{
&quot;targets&quot;: [
{
&quot;target_name&quot;: &quot;addon&quot;,
&quot;sources&quot;: [ &quot;addon.cc&quot; ]
}
]
}</code></pre>
<p>In cases where there is more than one <code>.cc</code> file, simply add the file name to the
<code>sources</code> array, e.g.:
</p>
<pre><code>&quot;sources&quot;: [&quot;addon.cc&quot;, &quot;myexample.cc&quot;]</code></pre>
<p>Now that you have your <code>binding.gyp</code> ready, you can configure and build the
addon:
</p>
<pre><code>$ node-gyp configure build</code></pre>
<h3>Function arguments<span><a class="mark" href="#all_function_arguments" id="all_function_arguments">#</a></span></h3>
<p>The following pattern illustrates how to read arguments from JavaScript
function calls and return a result. This is the main and only needed source
<code>addon.cc</code>:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
using namespace v8;
Handle&lt;Value&gt; Add(const Arguments&amp; args) {
HandleScope scope;
if (args.Length() &lt; 2) {
ThrowException(Exception::TypeError(String::New(&quot;Wrong number of arguments&quot;)));
return scope.Close(Undefined());
}
if (!args[0]-&gt;IsNumber() || !args[1]-&gt;IsNumber()) {
ThrowException(Exception::TypeError(String::New(&quot;Wrong arguments&quot;)));
return scope.Close(Undefined());
}
Local&lt;Number&gt; num = Number::New(args[0]-&gt;NumberValue() +
args[1]-&gt;NumberValue());
return scope.Close(num);
}
void Init(Handle&lt;Object&gt; exports) {
exports-&gt;Set(String::NewSymbol(&quot;add&quot;),
FunctionTemplate::New(Add)-&gt;GetFunction());
}
NODE_MODULE(addon, Init)</code></pre>
<p>You can test it with the following JavaScript snippet:
</p>
<pre><code>var addon = require(&#39;./build/Release/addon&#39;);
console.log( &#39;This should be eight:&#39;, addon.add(3,5) );</code></pre>
<h3>Callbacks<span><a class="mark" href="#all_callbacks" id="all_callbacks">#</a></span></h3>
<p>You can pass JavaScript functions to a C++ function and execute them from
there. Here&#39;s <code>addon.cc</code>:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
using namespace v8;
Handle&lt;Value&gt; RunCallback(const Arguments&amp; args) {
HandleScope scope;
Local&lt;Function&gt; cb = Local&lt;Function&gt;::Cast(args[0]);
const unsigned argc = 1;
Local&lt;Value&gt; argv[argc] = { Local&lt;Value&gt;::New(String::New(&quot;hello world&quot;)) };
cb-&gt;Call(Context::GetCurrent()-&gt;Global(), argc, argv);
return scope.Close(Undefined());
}
void Init(Handle&lt;Object&gt; exports, Handle&lt;Object&gt; module) {
module-&gt;Set(String::NewSymbol(&quot;exports&quot;),
FunctionTemplate::New(RunCallback)-&gt;GetFunction());
}
NODE_MODULE(addon, Init)</code></pre>
<p>Note that this example uses a two-argument form of <code>Init()</code> that receives
the full <code>module</code> object as the second argument. This allows the addon
to completely overwrite <code>exports</code> with a single function instead of
adding the function as a property of <code>exports</code>.
</p>
<p>To test it run the following JavaScript snippet:
</p>
<pre><code>var addon = require(&#39;./build/Release/addon&#39;);
addon(function(msg){
console.log(msg); // &#39;hello world&#39;
});</code></pre>
<h3>Object factory<span><a class="mark" href="#all_object_factory" id="all_object_factory">#</a></span></h3>
<p>You can create and return new objects from within a C++ function with this
<code>addon.cc</code> pattern, which returns an object with property <code>msg</code> that echoes
the string passed to <code>createObject()</code>:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
using namespace v8;
Handle&lt;Value&gt; CreateObject(const Arguments&amp; args) {
HandleScope scope;
Local&lt;Object&gt; obj = Object::New();
obj-&gt;Set(String::NewSymbol(&quot;msg&quot;), args[0]-&gt;ToString());
return scope.Close(obj);
}
void Init(Handle&lt;Object&gt; exports, Handle&lt;Object&gt; module) {
module-&gt;Set(String::NewSymbol(&quot;exports&quot;),
FunctionTemplate::New(CreateObject)-&gt;GetFunction());
}
NODE_MODULE(addon, Init)</code></pre>
<p>To test it in JavaScript:
</p>
<pre><code>var addon = require(&#39;./build/Release/addon&#39;);
var obj1 = addon(&#39;hello&#39;);
var obj2 = addon(&#39;world&#39;);
console.log(obj1.msg+&#39; &#39;+obj2.msg); // &#39;hello world&#39;</code></pre>
<h3>Function factory<span><a class="mark" href="#all_function_factory" id="all_function_factory">#</a></span></h3>
<p>This pattern illustrates how to create and return a JavaScript function that
wraps a C++ function:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
using namespace v8;
Handle&lt;Value&gt; MyFunction(const Arguments&amp; args) {
HandleScope scope;
return scope.Close(String::New(&quot;hello world&quot;));
}
Handle&lt;Value&gt; CreateFunction(const Arguments&amp; args) {
HandleScope scope;
Local&lt;FunctionTemplate&gt; tpl = FunctionTemplate::New(MyFunction);
Local&lt;Function&gt; fn = tpl-&gt;GetFunction();
fn-&gt;SetName(String::NewSymbol(&quot;theFunction&quot;)); // omit this to make it anonymous
return scope.Close(fn);
}
void Init(Handle&lt;Object&gt; exports, Handle&lt;Object&gt; module) {
module-&gt;Set(String::NewSymbol(&quot;exports&quot;),
FunctionTemplate::New(CreateFunction)-&gt;GetFunction());
}
NODE_MODULE(addon, Init)</code></pre>
<p>To test:
</p>
<pre><code>var addon = require(&#39;./build/Release/addon&#39;);
var fn = addon();
console.log(fn()); // &#39;hello world&#39;</code></pre>
<h3>Wrapping C++ objects<span><a class="mark" href="#all_wrapping_c_objects" id="all_wrapping_c_objects">#</a></span></h3>
<p>Here we will create a wrapper for a C++ object/class <code>MyObject</code> that can be
instantiated in JavaScript through the <code>new</code> operator. First prepare the main
module <code>addon.cc</code>:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
#include &quot;myobject.h&quot;
using namespace v8;
void InitAll(Handle&lt;Object&gt; exports) {
MyObject::Init(exports);
}
NODE_MODULE(addon, InitAll)</code></pre>
<p>Then in <code>myobject.h</code> make your wrapper inherit from <code>node::ObjectWrap</code>:
</p>
<pre><code>#ifndef MYOBJECT_H
#define MYOBJECT_H
#include &lt;node.h&gt;
class MyObject : public node::ObjectWrap {
public:
static void Init(v8::Handle&lt;v8::Object&gt; exports);
private:
explicit MyObject(double value = 0);
~MyObject();
static v8::Handle&lt;v8::Value&gt; New(const v8::Arguments&amp; args);
static v8::Handle&lt;v8::Value&gt; PlusOne(const v8::Arguments&amp; args);
static v8::Persistent&lt;v8::Function&gt; constructor;
double value_;
};
#endif</code></pre>
<p>And in <code>myobject.cc</code> implement the various methods that you want to expose.
Here we expose the method <code>plusOne</code> by adding it to the constructor&#39;s
prototype:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
#include &quot;myobject.h&quot;
using namespace v8;
Persistent&lt;Function&gt; MyObject::constructor;
MyObject::MyObject(double value) : value_(value) {
}
MyObject::~MyObject() {
}
void MyObject::Init(Handle&lt;Object&gt; exports) {
// Prepare constructor template
Local&lt;FunctionTemplate&gt; tpl = FunctionTemplate::New(New);
tpl-&gt;SetClassName(String::NewSymbol(&quot;MyObject&quot;));
tpl-&gt;InstanceTemplate()-&gt;SetInternalFieldCount(1);
// Prototype
tpl-&gt;PrototypeTemplate()-&gt;Set(String::NewSymbol(&quot;plusOne&quot;),
FunctionTemplate::New(PlusOne)-&gt;GetFunction());
constructor = Persistent&lt;Function&gt;::New(tpl-&gt;GetFunction());
exports-&gt;Set(String::NewSymbol(&quot;MyObject&quot;), constructor);
}
Handle&lt;Value&gt; MyObject::New(const Arguments&amp; args) {
HandleScope scope;
if (args.IsConstructCall()) {
// Invoked as constructor: `new MyObject(...)`
double value = args[0]-&gt;IsUndefined() ? 0 : args[0]-&gt;NumberValue();
MyObject* obj = new MyObject(value);
obj-&gt;Wrap(args.This());
return args.This();
} else {
// Invoked as plain function `MyObject(...)`, turn into construct call.
const int argc = 1;
Local&lt;Value&gt; argv[argc] = { args[0] };
return scope.Close(constructor-&gt;NewInstance(argc, argv));
}
}
Handle&lt;Value&gt; MyObject::PlusOne(const Arguments&amp; args) {
HandleScope scope;
MyObject* obj = ObjectWrap::Unwrap&lt;MyObject&gt;(args.This());
obj-&gt;value_ += 1;
return scope.Close(Number::New(obj-&gt;value_));
}</code></pre>
<p>Test it with:
</p>
<pre><code>var addon = require(&#39;./build/Release/addon&#39;);
var obj = new addon.MyObject(10);
console.log( obj.plusOne() ); // 11
console.log( obj.plusOne() ); // 12
console.log( obj.plusOne() ); // 13</code></pre>
<h3>Factory of wrapped objects<span><a class="mark" href="#all_factory_of_wrapped_objects" id="all_factory_of_wrapped_objects">#</a></span></h3>
<p>This is useful when you want to be able to create native objects without
explicitly instantiating them with the <code>new</code> operator in JavaScript, e.g.
</p>
<pre><code>var obj = addon.createObject();
// instead of:
// var obj = new addon.Object();</code></pre>
<p>Let&#39;s register our <code>createObject</code> method in <code>addon.cc</code>:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
#include &quot;myobject.h&quot;
using namespace v8;
Handle&lt;Value&gt; CreateObject(const Arguments&amp; args) {
HandleScope scope;
return scope.Close(MyObject::NewInstance(args));
}
void InitAll(Handle&lt;Object&gt; exports, Handle&lt;Object&gt; module) {
MyObject::Init();
module-&gt;Set(String::NewSymbol(&quot;exports&quot;),
FunctionTemplate::New(CreateObject)-&gt;GetFunction());
}
NODE_MODULE(addon, InitAll)</code></pre>
<p>In <code>myobject.h</code> we now introduce the static method <code>NewInstance</code> that takes
care of instantiating the object (i.e. it does the job of <code>new</code> in JavaScript):
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#ifndef MYOBJECT_H
#define MYOBJECT_H
#include &lt;node.h&gt;
class MyObject : public node::ObjectWrap {
public:
static void Init();
static v8::Handle&lt;v8::Value&gt; NewInstance(const v8::Arguments&amp; args);
private:
explicit MyObject(double value = 0);
~MyObject();
static v8::Handle&lt;v8::Value&gt; New(const v8::Arguments&amp; args);
static v8::Handle&lt;v8::Value&gt; PlusOne(const v8::Arguments&amp; args);
static v8::Persistent&lt;v8::Function&gt; constructor;
double value_;
};
#endif</code></pre>
<p>The implementation is similar to the above in <code>myobject.cc</code>:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
#include &quot;myobject.h&quot;
using namespace v8;
Persistent&lt;Function&gt; MyObject::constructor;
MyObject::MyObject(double value) : value_(value) {
}
MyObject::~MyObject() {
}
void MyObject::Init() {
// Prepare constructor template
Local&lt;FunctionTemplate&gt; tpl = FunctionTemplate::New(New);
tpl-&gt;SetClassName(String::NewSymbol(&quot;MyObject&quot;));
tpl-&gt;InstanceTemplate()-&gt;SetInternalFieldCount(1);
// Prototype
tpl-&gt;PrototypeTemplate()-&gt;Set(String::NewSymbol(&quot;plusOne&quot;),
FunctionTemplate::New(PlusOne)-&gt;GetFunction());
constructor = Persistent&lt;Function&gt;::New(tpl-&gt;GetFunction());
}
Handle&lt;Value&gt; MyObject::New(const Arguments&amp; args) {
HandleScope scope;
if (args.IsConstructCall()) {
// Invoked as constructor: `new MyObject(...)`
double value = args[0]-&gt;IsUndefined() ? 0 : args[0]-&gt;NumberValue();
MyObject* obj = new MyObject(value);
obj-&gt;Wrap(args.This());
return args.This();
} else {
// Invoked as plain function `MyObject(...)`, turn into construct call.
const int argc = 1;
Local&lt;Value&gt; argv[argc] = { args[0] };
return scope.Close(constructor-&gt;NewInstance(argc, argv));
}
}
Handle&lt;Value&gt; MyObject::NewInstance(const Arguments&amp; args) {
HandleScope scope;
const unsigned argc = 1;
Handle&lt;Value&gt; argv[argc] = { args[0] };
Local&lt;Object&gt; instance = constructor-&gt;NewInstance(argc, argv);
return scope.Close(instance);
}
Handle&lt;Value&gt; MyObject::PlusOne(const Arguments&amp; args) {
HandleScope scope;
MyObject* obj = ObjectWrap::Unwrap&lt;MyObject&gt;(args.This());
obj-&gt;value_ += 1;
return scope.Close(Number::New(obj-&gt;value_));
}</code></pre>
<p>Test it with:
</p>
<pre><code>var createObject = require(&#39;./build/Release/addon&#39;);
var obj = createObject(10);
console.log( obj.plusOne() ); // 11
console.log( obj.plusOne() ); // 12
console.log( obj.plusOne() ); // 13
var obj2 = createObject(20);
console.log( obj2.plusOne() ); // 21
console.log( obj2.plusOne() ); // 22
console.log( obj2.plusOne() ); // 23</code></pre>
<h3>Passing wrapped objects around<span><a class="mark" href="#all_passing_wrapped_objects_around" id="all_passing_wrapped_objects_around">#</a></span></h3>
<p>In addition to wrapping and returning C++ objects, you can pass them around
by unwrapping them with Node&#39;s <code>node::ObjectWrap::Unwrap</code> helper function.
In the following <code>addon.cc</code> we introduce a function <code>add()</code> that can take on two
<code>MyObject</code> objects:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
#include &quot;myobject.h&quot;
using namespace v8;
Handle&lt;Value&gt; CreateObject(const Arguments&amp; args) {
HandleScope scope;
return scope.Close(MyObject::NewInstance(args));
}
Handle&lt;Value&gt; Add(const Arguments&amp; args) {
HandleScope scope;
MyObject* obj1 = node::ObjectWrap::Unwrap&lt;MyObject&gt;(
args[0]-&gt;ToObject());
MyObject* obj2 = node::ObjectWrap::Unwrap&lt;MyObject&gt;(
args[1]-&gt;ToObject());
double sum = obj1-&gt;Value() + obj2-&gt;Value();
return scope.Close(Number::New(sum));
}
void InitAll(Handle&lt;Object&gt; exports) {
MyObject::Init();
exports-&gt;Set(String::NewSymbol(&quot;createObject&quot;),
FunctionTemplate::New(CreateObject)-&gt;GetFunction());
exports-&gt;Set(String::NewSymbol(&quot;add&quot;),
FunctionTemplate::New(Add)-&gt;GetFunction());
}
NODE_MODULE(addon, InitAll)</code></pre>
<p>To make things interesting we introduce a public method in <code>myobject.h</code> so we
can probe private values after unwrapping the object:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#ifndef MYOBJECT_H
#define MYOBJECT_H
#include &lt;node.h&gt;
class MyObject : public node::ObjectWrap {
public:
static void Init();
static v8::Handle&lt;v8::Value&gt; NewInstance(const v8::Arguments&amp; args);
double Value() const { return value_; }
private:
explicit MyObject(double value = 0);
~MyObject();
static v8::Handle&lt;v8::Value&gt; New(const v8::Arguments&amp; args);
static v8::Persistent&lt;v8::Function&gt; constructor;
double value_;
};
#endif</code></pre>
<p>The implementation of <code>myobject.cc</code> is similar as before:
</p>
<pre><code>#define BUILDING_NODE_EXTENSION
#include &lt;node.h&gt;
#include &quot;myobject.h&quot;
using namespace v8;
Persistent&lt;Function&gt; MyObject::constructor;
MyObject::MyObject(double value) : value_(value) {
}
MyObject::~MyObject() {
}
void MyObject::Init() {
// Prepare constructor template
Local&lt;FunctionTemplate&gt; tpl = FunctionTemplate::New(New);
tpl-&gt;SetClassName(String::NewSymbol(&quot;MyObject&quot;));
tpl-&gt;InstanceTemplate()-&gt;SetInternalFieldCount(1);
constructor = Persistent&lt;Function&gt;::New(tpl-&gt;GetFunction());
}
Handle&lt;Value&gt; MyObject::New(const Arguments&amp; args) {
HandleScope scope;
if (args.IsConstructCall()) {
// Invoked as constructor: `new MyObject(...)`
double value = args[0]-&gt;IsUndefined() ? 0 : args[0]-&gt;NumberValue();
MyObject* obj = new MyObject(value);
obj-&gt;Wrap(args.This());
return args.This();
} else {
// Invoked as plain function `MyObject(...)`, turn into construct call.
const int argc = 1;
Local&lt;Value&gt; argv[argc] = { args[0] };
return scope.Close(constructor-&gt;NewInstance(argc, argv));
}
}
Handle&lt;Value&gt; MyObject::NewInstance(const Arguments&amp; args) {
HandleScope scope;
const unsigned argc = 1;
Handle&lt;Value&gt; argv[argc] = { args[0] };
Local&lt;Object&gt; instance = constructor-&gt;NewInstance(argc, argv);
return scope.Close(instance);
}</code></pre>
<p>Test it with:
</p>
<pre><code>var addon = require(&#39;./build/Release/addon&#39;);
var obj1 = addon.createObject(10);
var obj2 = addon.createObject(20);
var result = addon.add(obj1, obj2);
console.log(result); // 30</code></pre>
<h1>process<span><a class="mark" href="#all_process_1" id="all_process_1">#</a></span></h1>
<!-- type=global -->
<p>The <code>process</code> object is a global object and can be accessed from anywhere.
It is an instance of <a href="events.html#events_class_events_eventemitter">EventEmitter</a>.
</p>
<h2>Event: &#39;exit&#39;<span><a class="mark" href="#all_event_exit" id="all_event_exit">#</a></span></h2>
<p>Emitted when the process is about to exit. This is a good hook to perform
constant time checks of the module&#39;s state (like for unit tests). The main
event loop will no longer be run after the &#39;exit&#39; callback finishes, so
timers may not be scheduled.
</p>
<p>Example of listening for <code>exit</code>:
</p>
<pre><code>process.on(&#39;exit&#39;, function() {
setTimeout(function() {
console.log(&#39;This will not run&#39;);
}, 0);
console.log(&#39;About to exit.&#39;);
});</code></pre>
<h2>Event: &#39;uncaughtException&#39;<span><a class="mark" href="#all_event_uncaughtexception" id="all_event_uncaughtexception">#</a></span></h2>
<p>Emitted when an exception bubbles all the way back to the event loop. If a
listener is added for this exception, the default action (which is to print
a stack trace and exit) will not occur.
</p>
<p>Example of listening for <code>uncaughtException</code>:
</p>
<pre><code>process.on(&#39;uncaughtException&#39;, function(err) {
console.log(&#39;Caught exception: &#39; + err);
});
setTimeout(function() {
console.log(&#39;This will still run.&#39;);
}, 500);
// Intentionally cause an exception, but don&#39;t catch it.
nonexistentFunc();
console.log(&#39;This will not run.&#39;);</code></pre>
<p>Note that <code>uncaughtException</code> is a very crude mechanism for exception
handling and may be removed in the future.
</p>
<p>Don&#39;t use it, use <a href="domain.html">domains</a> instead. If you do use it, restart
your application after every unhandled exception!
</p>
<p>Do <em>not</em> use it as the node.js equivalent of <code>On Error Resume Next</code>. An
unhandled exception means your application - and by extension node.js itself -
is in an undefined state. Blindly resuming means <em>anything</em> could happen.
</p>
<p>Think of resuming as pulling the power cord when you are upgrading your system.
Nine out of ten times nothing happens - but the 10th time, your system is bust.
</p>
<p>You have been warned.
</p>
<h2>Signal Events<span><a class="mark" href="#all_signal_events" id="all_signal_events">#</a></span></h2>
<!--type=event-->
<!--name=SIGINT, SIGHUP, etc.-->
<p>Emitted when the processes receives a signal. See sigaction(2) for a list of
standard POSIX signal names such as SIGINT, SIGHUP, etc.
</p>
<p>Example of listening for <code>SIGINT</code>:
</p>
<pre><code>// Start reading from stdin so we don&#39;t exit.
process.stdin.resume();
process.on(&#39;SIGINT&#39;, function() {
console.log(&#39;Got SIGINT. Press Control-D to exit.&#39;);
});</code></pre>
<p>An easy way to send the <code>SIGINT</code> signal is with <code>Control-C</code> in most terminal
programs.
</p>
<p>Note:
</p>
<ul>
<li><code>SIGUSR1</code> is reserved by node.js to start the debugger. It&#39;s possible to
install a listener but that won&#39;t stop the debugger from starting.</li>
<li><code>SIGTERM</code> and <code>SIGINT</code> have default handlers on non-Windows platforms that resets
the terminal mode before exiting with code <code>128 + signal number</code>. If one of
these signals has a listener installed, its default behaviour will be removed
(node will no longer exit).</li>
<li><code>SIGPIPE</code> is ignored by default, it can have a listener installed.</li>
<li><code>SIGHUP</code> is generated on Windows when the console window is closed, and on other
platforms under various similar conditions, see signal(7). It can have a
listener installed, however node will be unconditionally terminated by Windows
about 10 seconds later. On non-Windows platforms, the default behaviour of
<code>SIGHUP</code> is to terminate node, but once a listener has been installed its
default behaviour will be removed.</li>
<li><code>SIGTERM</code> is not supported on Windows, it can be listened on.</li>
<li><code>SIGINT</code> is supported on all platforms, and can usually be generated with
<code>CTRL+C</code> (though this may be configurable). It is not generated when terminal
raw mode is enabled.</li>
<li><code>SIGBREAK</code> is delivered on Windows when <code>CTRL+BREAK</code> is pressed, on non-Windows
platforms it can be listened on, but there is no way to send or generate it.</li>
<li><code>SIGWINCH</code> is delivered when the console has been resized. On Windows, this will
only happen on write to the console when the cursor is being moved, or when a
readable tty is used in raw mode.</li>
<li><code>SIGKILL</code> cannot have a listener installed, it will unconditionally terminate
node on all platforms.</li>
<li><code>SIGSTOP</code> cannot have a listener installed.</li>
</ul>
<h2>process.stdout<span><a class="mark" href="#all_process_stdout" id="all_process_stdout">#</a></span></h2>
<p>A <code>Writable Stream</code> to <code>stdout</code>.
</p>
<p>Example: the definition of <code>console.log</code>
</p>
<pre><code>console.log = function(d) {
process.stdout.write(d + &#39;\n&#39;);
};</code></pre>
<p><code>process.stderr</code> and <code>process.stdout</code> are unlike other streams in Node in
that writes to them are usually blocking. They are blocking in the case
that they refer to regular files or TTY file descriptors. In the case they
refer to pipes, they are non-blocking like other streams.
</p>
<p>To check if Node is being run in a TTY context, read the <code>isTTY</code> property
on <code>process.stderr</code>, <code>process.stdout</code>, or <code>process.stdin</code>:
</p>
<pre><code>$ node -p &quot;Boolean(process.stdin.isTTY)&quot;
true
$ echo &quot;foo&quot; | node -p &quot;Boolean(process.stdin.isTTY)&quot;
false
$ node -p &quot;Boolean(process.stdout.isTTY)&quot;
true
$ node -p &quot;Boolean(process.stdout.isTTY)&quot; | cat
false</code></pre>
<p>See <a href="tty.html#tty_tty">the tty docs</a> for more information.
</p>
<h2>process.stderr<span><a class="mark" href="#all_process_stderr" id="all_process_stderr">#</a></span></h2>
<p>A writable stream to stderr.
</p>
<p><code>process.stderr</code> and <code>process.stdout</code> are unlike other streams in Node in
that writes to them are usually blocking. They are blocking in the case
that they refer to regular files or TTY file descriptors. In the case they
refer to pipes, they are non-blocking like other streams.
</p>
<h2>process.stdin<span><a class="mark" href="#all_process_stdin" id="all_process_stdin">#</a></span></h2>
<p>A <code>Readable Stream</code> for stdin. The stdin stream is paused by default, so one
must call <code>process.stdin.resume()</code> to read from it.
</p>
<p>Example of opening standard input and listening for both events:
</p>
<pre><code>process.stdin.resume();
process.stdin.setEncoding(&#39;utf8&#39;);
process.stdin.on(&#39;data&#39;, function(chunk) {
process.stdout.write(&#39;data: &#39; + chunk);
});
process.stdin.on(&#39;end&#39;, function() {
process.stdout.write(&#39;end&#39;);
});</code></pre>
<h2>process.argv<span><a class="mark" href="#all_process_argv" id="all_process_argv">#</a></span></h2>
<p>An array containing the command line arguments. The first element will be
&#39;node&#39;, the second element will be the name of the JavaScript file. The
next elements will be any additional command line arguments.
</p>
<pre><code>// print process.argv
process.argv.forEach(function(val, index, array) {
console.log(index + &#39;: &#39; + val);
});</code></pre>
<p>This will generate:
</p>
<pre><code>$ node process-2.js one two=three four
0: node
1: /Users/mjr/work/node/process-2.js
2: one
3: two=three
4: four</code></pre>
<h2>process.execPath<span><a class="mark" href="#all_process_execpath" id="all_process_execpath">#</a></span></h2>
<p>This is the absolute pathname of the executable that started the process.
</p>
<p>Example:
</p>
<pre><code>/usr/local/bin/node</code></pre>
<h2>process.execArgv<span><a class="mark" href="#all_process_execargv" id="all_process_execargv">#</a></span></h2>
<p>This is the set of node-specific command line options from the
executable that started the process. These options do not show up in
<code>process.argv</code>, and do not include the node executable, the name of
the script, or any options following the script name. These options
are useful in order to spawn child processes with the same execution
environment as the parent.
</p>
<p>Example:
</p>
<pre><code>$ node --harmony script.js --version</code></pre>
<p>results in process.execArgv:
</p>
<pre><code>[&#39;--harmony&#39;]</code></pre>
<p>and process.argv:
</p>
<pre><code>[&#39;/usr/local/bin/node&#39;, &#39;script.js&#39;, &#39;--version&#39;]</code></pre>
<h2>process.abort()<span><a class="mark" href="#all_process_abort" id="all_process_abort">#</a></span></h2>
<p>This causes node to emit an abort. This will cause node to exit and
generate a core file.
</p>
<h2>process.chdir(directory)<span><a class="mark" href="#all_process_chdir_directory" id="all_process_chdir_directory">#</a></span></h2>
<p>Changes the current working directory of the process or throws an exception if that fails.
</p>
<pre><code>console.log(&#39;Starting directory: &#39; + process.cwd());
try {
process.chdir(&#39;/tmp&#39;);
console.log(&#39;New directory: &#39; + process.cwd());
}
catch (err) {
console.log(&#39;chdir: &#39; + err);
}</code></pre>
<h2>process.cwd()<span><a class="mark" href="#all_process_cwd" id="all_process_cwd">#</a></span></h2>
<p>Returns the current working directory of the process.
</p>
<pre><code>console.log(&#39;Current directory: &#39; + process.cwd());</code></pre>
<h2>process.env<span><a class="mark" href="#all_process_env" id="all_process_env">#</a></span></h2>
<p>An object containing the user environment. See environ(7).
</p>
<h2>process.exit([code])<span><a class="mark" href="#all_process_exit_code" id="all_process_exit_code">#</a></span></h2>
<p>Ends the process with the specified <code>code</code>. If omitted, exit uses the
&#39;success&#39; code <code>0</code>.
</p>
<p>To exit with a &#39;failure&#39; code:
</p>
<pre><code>process.exit(1);</code></pre>
<p>The shell that executed node should see the exit code as 1.
</p>
<h2>process.getgid()<span><a class="mark" href="#all_process_getgid" id="all_process_getgid">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Gets the group identity of the process. (See getgid(2).)
This is the numerical group id, not the group name.
</p>
<pre><code>if (process.getgid) {
console.log(&#39;Current gid: &#39; + process.getgid());
}</code></pre>
<h2>process.setgid(id)<span><a class="mark" href="#all_process_setgid_id" id="all_process_setgid_id">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Sets the group identity of the process. (See setgid(2).) This accepts either
a numerical ID or a groupname string. If a groupname is specified, this method
blocks while resolving it to a numerical ID.
</p>
<pre><code>if (process.getgid &amp;&amp; process.setgid) {
console.log(&#39;Current gid: &#39; + process.getgid());
try {
process.setgid(501);
console.log(&#39;New gid: &#39; + process.getgid());
}
catch (err) {
console.log(&#39;Failed to set gid: &#39; + err);
}
}</code></pre>
<h2>process.getuid()<span><a class="mark" href="#all_process_getuid" id="all_process_getuid">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Gets the user identity of the process. (See getuid(2).)
This is the numerical userid, not the username.
</p>
<pre><code>if (process.getuid) {
console.log(&#39;Current uid: &#39; + process.getuid());
}</code></pre>
<h2>process.setuid(id)<span><a class="mark" href="#all_process_setuid_id" id="all_process_setuid_id">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Sets the user identity of the process. (See setuid(2).) This accepts either
a numerical ID or a username string. If a username is specified, this method
blocks while resolving it to a numerical ID.
</p>
<pre><code>if (process.getuid &amp;&amp; process.setuid) {
console.log(&#39;Current uid: &#39; + process.getuid());
try {
process.setuid(501);
console.log(&#39;New uid: &#39; + process.getuid());
}
catch (err) {
console.log(&#39;Failed to set uid: &#39; + err);
}
}</code></pre>
<h2>process.getgroups()<span><a class="mark" href="#all_process_getgroups" id="all_process_getgroups">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Returns an array with the supplementary group IDs. POSIX leaves it unspecified
if the effective group ID is included but node.js ensures it always is.
</p>
<h2>process.setgroups(groups)<span><a class="mark" href="#all_process_setgroups_groups" id="all_process_setgroups_groups">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Sets the supplementary group IDs. This is a privileged operation, meaning you
need to be root or have the CAP_SETGID capability.
</p>
<p>The list can contain group IDs, group names or both.
</p>
<h2>process.initgroups(user, extra_group)<span><a class="mark" href="#all_process_initgroups_user_extra_group" id="all_process_initgroups_user_extra_group">#</a></span></h2>
<p>Note: this function is only available on POSIX platforms (i.e. not Windows)
</p>
<p>Reads /etc/group and initializes the group access list, using all groups of
which the user is a member. This is a privileged operation, meaning you need
to be root or have the CAP_SETGID capability.
</p>
<p><code>user</code> is a user name or user ID. <code>extra_group</code> is a group name or group ID.
</p>
<p>Some care needs to be taken when dropping privileges. Example:
</p>
<pre><code>console.log(process.getgroups()); // [ 0 ]
process.initgroups(&#39;bnoordhuis&#39;, 1000); // switch user
console.log(process.getgroups()); // [ 27, 30, 46, 1000, 0 ]
process.setgid(1000); // drop root gid
console.log(process.getgroups()); // [ 27, 30, 46, 1000 ]</code></pre>
<h2>process.version<span><a class="mark" href="#all_process_version" id="all_process_version">#</a></span></h2>
<p>A compiled-in property that exposes <code>NODE_VERSION</code>.
</p>
<pre><code>console.log(&#39;Version: &#39; + process.version);</code></pre>
<h2>process.versions<span><a class="mark" href="#all_process_versions" id="all_process_versions">#</a></span></h2>
<p>A property exposing version strings of node and its dependencies.
</p>
<pre><code>console.log(process.versions);</code></pre>
<p>Will print something like:
</p>
<pre><code>{ http_parser: &#39;1.0&#39;,
node: &#39;0.10.4&#39;,
v8: &#39;3.14.5.8&#39;,
ares: &#39;1.9.0-DEV&#39;,
uv: &#39;0.10.3&#39;,
zlib: &#39;1.2.3&#39;,
modules: &#39;11&#39;,
openssl: &#39;1.0.1e&#39; }</code></pre>
<h2>process.config<span><a class="mark" href="#all_process_config" id="all_process_config">#</a></span></h2>
<p>An Object containing the JavaScript representation of the configure options
that were used to compile the current node executable. This is the same as
the &quot;config.gypi&quot; file that was produced when running the <code>./configure</code> script.
</p>
<p>An example of the possible output looks like:
</p>
<pre><code>{ target_defaults:
{ cflags: [],
default_configuration: &#39;Release&#39;,
defines: [],
include_dirs: [],
libraries: [] },
variables:
{ host_arch: &#39;x64&#39;,
node_install_npm: &#39;true&#39;,
node_prefix: &#39;&#39;,
node_shared_cares: &#39;false&#39;,
node_shared_http_parser: &#39;false&#39;,
node_shared_libuv: &#39;false&#39;,
node_shared_v8: &#39;false&#39;,
node_shared_zlib: &#39;false&#39;,
node_use_dtrace: &#39;false&#39;,
node_use_openssl: &#39;true&#39;,
node_shared_openssl: &#39;false&#39;,
strict_aliasing: &#39;true&#39;,
target_arch: &#39;x64&#39;,
v8_use_snapshot: &#39;true&#39; } }</code></pre>
<h2>process.kill(pid, [signal])<span><a class="mark" href="#all_process_kill_pid_signal" id="all_process_kill_pid_signal">#</a></span></h2>
<p>Send a signal to a process. <code>pid</code> is the process id and <code>signal</code> is the
string describing the signal to send. Signal names are strings like
&#39;SIGINT&#39; or &#39;SIGHUP&#39;. If omitted, the signal will be &#39;SIGTERM&#39;.
See kill(2) for more information.
</p>
<p>Will throw an error if target does not exist, and as a special case, a signal of
<code>0</code> can be used to test for the existence of a process.
</p>
<p>Note that just because the name of this function is <code>process.kill</code>, it is
really just a signal sender, like the <code>kill</code> system call. The signal sent
may do something other than kill the target process.
</p>
<p>Example of sending a signal to yourself:
</p>
<pre><code>process.on(&#39;SIGHUP&#39;, function() {
console.log(&#39;Got SIGHUP signal.&#39;);
});
setTimeout(function() {
console.log(&#39;Exiting.&#39;);
process.exit(0);
}, 100);
process.kill(process.pid, &#39;SIGHUP&#39;);</code></pre>
<p>Note: When SIGUSR1 is received by Node.js it starts the debugger, see
<a href="#process_signal_events">Signal Events</a>.
</p>
<h2>process.pid<span><a class="mark" href="#all_process_pid" id="all_process_pid">#</a></span></h2>
<p>The PID of the process.
</p>
<pre><code>console.log(&#39;This process is pid &#39; + process.pid);</code></pre>
<h2>process.title<span><a class="mark" href="#all_process_title" id="all_process_title">#</a></span></h2>
<p>Getter/setter to set what is displayed in &#39;ps&#39;.
</p>
<p>When used as a setter, the maximum length is platform-specific and probably
short.
</p>
<p>On Linux and OS X, it&#39;s limited to the size of the binary name plus the
length of the command line arguments because it overwrites the argv memory.
</p>
<p>v0.8 allowed for longer process title strings by also overwriting the environ
memory but that was potentially insecure/confusing in some (rather obscure)
cases.
</p>
<h2>process.arch<span><a class="mark" href="#all_process_arch" id="all_process_arch">#</a></span></h2>
<p>What processor architecture you&#39;re running on: <code>&#39;arm&#39;</code>, <code>&#39;ia32&#39;</code>, or <code>&#39;x64&#39;</code>.
</p>
<pre><code>console.log(&#39;This processor architecture is &#39; + process.arch);</code></pre>
<h2>process.platform<span><a class="mark" href="#all_process_platform" id="all_process_platform">#</a></span></h2>
<p>What platform you&#39;re running on:
<code>&#39;darwin&#39;</code>, <code>&#39;freebsd&#39;</code>, <code>&#39;linux&#39;</code>, <code>&#39;sunos&#39;</code> or <code>&#39;win32&#39;</code>
</p>
<pre><code>console.log(&#39;This platform is &#39; + process.platform);</code></pre>
<h2>process.memoryUsage()<span><a class="mark" href="#all_process_memoryusage" id="all_process_memoryusage">#</a></span></h2>
<p>Returns an object describing the memory usage of the Node process
measured in bytes.
</p>
<pre><code>var util = require(&#39;util&#39;);
console.log(util.inspect(process.memoryUsage()));</code></pre>
<p>This will generate:
</p>
<pre><code>{ rss: 4935680,
heapTotal: 1826816,
heapUsed: 650472 }</code></pre>
<p><code>heapTotal</code> and <code>heapUsed</code> refer to V8&#39;s memory usage.
</p>
<h2>process.nextTick(callback)<span><a class="mark" href="#all_process_nexttick_callback" id="all_process_nexttick_callback">#</a></span></h2>
<p>On the next loop around the event loop call this callback.
This is <em>not</em> a simple alias to <code>setTimeout(fn, 0)</code>, it&#39;s much more
efficient. It typically runs before any other I/O events fire, but there
are some exceptions. See <code>process.maxTickDepth</code> below.
</p>
<pre><code>process.nextTick(function() {
console.log(&#39;nextTick callback&#39;);
});</code></pre>
<p>This is important in developing APIs where you want to give the user the
chance to assign event handlers after an object has been constructed,
but before any I/O has occurred.
</p>
<pre><code>function MyThing(options) {
this.setupOptions(options);
process.nextTick(function() {
this.startDoingStuff();
}.bind(this));
}
var thing = new MyThing();
thing.getReadyForStuff();
// thing.startDoingStuff() gets called now, not before.</code></pre>
<p>It is very important for APIs to be either 100% synchronous or 100%
asynchronous. Consider this example:
</p>
<pre><code>// WARNING! DO NOT USE! BAD UNSAFE HAZARD!
function maybeSync(arg, cb) {
if (arg) {
cb();
return;
}
fs.stat(&#39;file&#39;, cb);
}</code></pre>
<p>This API is hazardous. If you do this:
</p>
<pre><code>maybeSync(true, function() {
foo();
});
bar();</code></pre>
<p>then it&#39;s not clear whether <code>foo()</code> or <code>bar()</code> will be called first.
</p>
<p>This approach is much better:
</p>
<pre><code>function definitelyAsync(arg, cb) {
if (arg) {
process.nextTick(cb);
return;
}
fs.stat(&#39;file&#39;, cb);
}</code></pre>
<h2>process.maxTickDepth<span><a class="mark" href="#all_process_maxtickdepth" id="all_process_maxtickdepth">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Number</span> Default = 1000</li>
</div></ul>
<p>Callbacks passed to <code>process.nextTick</code> will <em>usually</em> be called at the
end of the current flow of execution, and are thus approximately as fast
as calling a function synchronously. Left unchecked, this would starve
the event loop, preventing any I/O from occurring.
</p>
<p>Consider this code:
</p>
<pre><code>process.nextTick(function foo() {
process.nextTick(foo);
});</code></pre>
<p>In order to avoid the situation where Node is blocked by an infinite
loop of recursive series of nextTick calls, it defers to allow some I/O
to be done every so often.
</p>
<p>The <code>process.maxTickDepth</code> value is the maximum depth of
nextTick-calling nextTick-callbacks that will be evaluated before
allowing other forms of I/O to occur.
</p>
<h2>process.umask([mask])<span><a class="mark" href="#all_process_umask_mask" id="all_process_umask_mask">#</a></span></h2>
<p>Sets or reads the process&#39;s file mode creation mask. Child processes inherit
the mask from the parent process. Returns the old mask if <code>mask</code> argument is
given, otherwise returns the current mask.
</p>
<pre><code>var oldmask, newmask = 0644;
oldmask = process.umask(newmask);
console.log(&#39;Changed umask from: &#39; + oldmask.toString(8) +
&#39; to &#39; + newmask.toString(8));</code></pre>
<h2>process.uptime()<span><a class="mark" href="#all_process_uptime" id="all_process_uptime">#</a></span></h2>
<p>Number of seconds Node has been running.
</p>
<h2>process.hrtime()<span><a class="mark" href="#all_process_hrtime" id="all_process_hrtime">#</a></span></h2>
<p>Returns the current high-resolution real time in a <code>[seconds, nanoseconds]</code>
tuple Array. It is relative to an arbitrary time in the past. It is not
related to the time of day and therefore not subject to clock drift. The
primary use is for measuring performance between intervals.
</p>
<p>You may pass in the result of a previous call to <code>process.hrtime()</code> to get
a diff reading, useful for benchmarks and measuring intervals:
</p>
<pre><code>var time = process.hrtime();
// [ 1800216, 25 ]
setTimeout(function() {
var diff = process.hrtime(time);
// [ 1, 552 ]
console.log(&#39;benchmark took %d nanoseconds&#39;, diff[0] * 1e9 + diff[1]);
// benchmark took 1000000527 nanoseconds
}, 1000);</code></pre>
<h1>util<span><a class="mark" href="#all_util" id="all_util">#</a></span></h1>
<pre class="api_stability_4">Stability: 4 - API Frozen</pre><p>These functions are in the module <code>&#39;util&#39;</code>. Use <code>require(&#39;util&#39;)</code> to access
them.
</p>
<h2>util.format(format, [...])<span><a class="mark" href="#all_util_format_format" id="all_util_format_format">#</a></span></h2>
<p>Returns a formatted string using the first argument as a <code>printf</code>-like format.
</p>
<p>The first argument is a string that contains zero or more <em>placeholders</em>.
Each placeholder is replaced with the converted value from its corresponding
argument. Supported placeholders are:
</p>
<ul>
<li><code>%s</code> - String.</li>
<li><code>%d</code> - Number (both integer and float).</li>
<li><code>%j</code> - JSON.</li>
<li><code>%</code> - single percent sign (<code>&#39;%&#39;</code>). This does not consume an argument.</li>
</ul>
<p>If the placeholder does not have a corresponding argument, the placeholder is
not replaced.
</p>
<pre><code>util.format(&#39;%s:%s&#39;, &#39;foo&#39;); // &#39;foo:%s&#39;</code></pre>
<p>If there are more arguments than placeholders, the extra arguments are
converted to strings with <code>util.inspect()</code> and these strings are concatenated,
delimited by a space.
</p>
<pre><code>util.format(&#39;%s:%s&#39;, &#39;foo&#39;, &#39;bar&#39;, &#39;baz&#39;); // &#39;foo:bar baz&#39;</code></pre>
<p>If the first argument is not a format string then <code>util.format()</code> returns
a string that is the concatenation of all its arguments separated by spaces.
Each argument is converted to a string with <code>util.inspect()</code>.
</p>
<pre><code>util.format(1, 2, 3); // &#39;1 2 3&#39;</code></pre>
<h2>util.debug(string)<span><a class="mark" href="#all_util_debug_string" id="all_util_debug_string">#</a></span></h2>
<p>A synchronous output function. Will block the process and
output <code>string</code> immediately to <code>stderr</code>.
</p>
<pre><code>require(&#39;util&#39;).debug(&#39;message on stderr&#39;);</code></pre>
<h2>util.error([...])<span><a class="mark" href="#all_util_error" id="all_util_error">#</a></span></h2>
<p>Same as <code>util.debug()</code> except this will output all arguments immediately to
<code>stderr</code>.
</p>
<h2>util.puts([...])<span><a class="mark" href="#all_util_puts" id="all_util_puts">#</a></span></h2>
<p>A synchronous output function. Will block the process and output all arguments
to <code>stdout</code> with newlines after each argument.
</p>
<h2>util.print([...])<span><a class="mark" href="#all_util_print" id="all_util_print">#</a></span></h2>
<p>A synchronous output function. Will block the process, cast each argument to a
string then output to <code>stdout</code>. Does not place newlines after each argument.
</p>
<h2>util.log(string)<span><a class="mark" href="#all_util_log_string" id="all_util_log_string">#</a></span></h2>
<p>Output with timestamp on <code>stdout</code>.
</p>
<pre><code>require(&#39;util&#39;).log(&#39;Timestamped message.&#39;);</code></pre>
<h2>util.inspect(object, [options])<span><a class="mark" href="#all_util_inspect_object_options" id="all_util_inspect_object_options">#</a></span></h2>
<p>Return a string representation of <code>object</code>, which is useful for debugging.
</p>
<p>An optional <em>options</em> object may be passed that alters certain aspects of the
formatted string:
</p>
<ul>
<li><p><code>showHidden</code> - if <code>true</code> then the object&#39;s non-enumerable properties will be
shown too. Defaults to <code>false</code>.</p>
</li>
<li><p><code>depth</code> - tells <code>inspect</code> how many times to recurse while formatting the
object. This is useful for inspecting large complicated objects. Defaults to
<code>2</code>. To make it recurse indefinitely pass <code>null</code>.</p>
</li>
<li><p><code>colors</code> - if <code>true</code>, then the output will be styled with ANSI color codes.
Defaults to <code>false</code>. Colors are customizable, see below.</p>
</li>
<li><p><code>customInspect</code> - if <code>false</code>, then custom <code>inspect()</code> functions defined on the
objects being inspected won&#39;t be called. Defaults to <code>true</code>.</p>
</li>
</ul>
<p>Example of inspecting all properties of the <code>util</code> object:
</p>
<pre><code>var util = require(&#39;util&#39;);
console.log(util.inspect(util, { showHidden: true, depth: null }));</code></pre>
<h3>Customizing <code>util.inspect</code> colors<span><a class="mark" href="#all_customizing_util_inspect_colors" id="all_customizing_util_inspect_colors">#</a></span></h3>
<p>Color output (if enabled) of <code>util.inspect</code> is customizable globally
via <code>util.inspect.styles</code> and <code>util.inspect.colors</code> objects.
</p>
<p><code>util.inspect.styles</code> is a map assigning each style a color
from <code>util.inspect.colors</code>.
Highlighted styles and their default values are:
<em> <code>number</code> (yellow)
</em> <code>boolean</code> (yellow)
<em> <code>string</code> (green)
</em> <code>date</code> (magenta)
<em> <code>regexp</code> (red)
</em> <code>null</code> (bold)
<em> <code>undefined</code> (grey)
</em> <code>special</code> - only function at this time (cyan)
* <code>name</code> (intentionally no styling)
</p>
<p>Predefined color codes are: <code>white</code>, <code>grey</code>, <code>black</code>, <code>blue</code>, <code>cyan</code>,
<code>green</code>, <code>magenta</code>, <code>red</code> and <code>yellow</code>.
There are also <code>bold</code>, <code>italic</code>, <code>underline</code> and <code>inverse</code> codes.
</p>
<p>Objects also may define their own <code>inspect(depth)</code> function which <code>util.inspect()</code>
will invoke and use the result of when inspecting the object:
</p>
<pre><code>var util = require(&#39;util&#39;);
var obj = { name: &#39;nate&#39; };
obj.inspect = function(depth) {
return &#39;{&#39; + this.name + &#39;}&#39;;
};
util.inspect(obj);
// &quot;{nate}&quot;</code></pre>
<h2>util.isArray(object)<span><a class="mark" href="#all_util_isarray_object" id="all_util_isarray_object">#</a></span></h2>
<p>Returns <code>true</code> if the given &quot;object&quot; is an <code>Array</code>. <code>false</code> otherwise.
</p>
<pre><code>var util = require(&#39;util&#39;);
util.isArray([])
// true
util.isArray(new Array)
// true
util.isArray({})
// false</code></pre>
<h2>util.isRegExp(object)<span><a class="mark" href="#all_util_isregexp_object" id="all_util_isregexp_object">#</a></span></h2>
<p>Returns <code>true</code> if the given &quot;object&quot; is a <code>RegExp</code>. <code>false</code> otherwise.
</p>
<pre><code>var util = require(&#39;util&#39;);
util.isRegExp(/some regexp/)
// true
util.isRegExp(new RegExp(&#39;another regexp&#39;))
// true
util.isRegExp({})
// false</code></pre>
<h2>util.isDate(object)<span><a class="mark" href="#all_util_isdate_object" id="all_util_isdate_object">#</a></span></h2>
<p>Returns <code>true</code> if the given &quot;object&quot; is a <code>Date</code>. <code>false</code> otherwise.
</p>
<pre><code>var util = require(&#39;util&#39;);
util.isDate(new Date())
// true
util.isDate(Date())
// false (without &#39;new&#39; returns a String)
util.isDate({})
// false</code></pre>
<h2>util.isError(object)<span><a class="mark" href="#all_util_iserror_object" id="all_util_iserror_object">#</a></span></h2>
<p>Returns <code>true</code> if the given &quot;object&quot; is an <code>Error</code>. <code>false</code> otherwise.
</p>
<pre><code>var util = require(&#39;util&#39;);
util.isError(new Error())
// true
util.isError(new TypeError())
// true
util.isError({ name: &#39;Error&#39;, message: &#39;an error occurred&#39; })
// false</code></pre>
<h2>util.pump(readableStream, writableStream, [callback])<span><a class="mark" href="#all_util_pump_readablestream_writablestream_callback" id="all_util_pump_readablestream_writablestream_callback">#</a></span></h2>
<pre class="api_stability_0">Stability: 0 - Deprecated: Use readableStream.pipe(writableStream)</pre><p>Read the data from <code>readableStream</code> and send it to the <code>writableStream</code>.
When <code>writableStream.write(data)</code> returns <code>false</code> <code>readableStream</code> will be
paused until the <code>drain</code> event occurs on the <code>writableStream</code>. <code>callback</code> gets
an error as its only argument and is called when <code>writableStream</code> is closed or
when an error occurs.
</p>
<h2>util.inherits(constructor, superConstructor)<span><a class="mark" href="#all_util_inherits_constructor_superconstructor" id="all_util_inherits_constructor_superconstructor">#</a></span></h2>
<p>Inherit the prototype methods from one
<a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/constructor">constructor</a>
into another. The prototype of <code>constructor</code> will be set to a new
object created from <code>superConstructor</code>.
</p>
<p>As an additional convenience, <code>superConstructor</code> will be accessible
through the <code>constructor.super_</code> property.
</p>
<pre><code>var util = require(&quot;util&quot;);
var events = require(&quot;events&quot;);
function MyStream() {
events.EventEmitter.call(this);
}
util.inherits(MyStream, events.EventEmitter);
MyStream.prototype.write = function(data) {
this.emit(&quot;data&quot;, data);
}
var stream = new MyStream();
console.log(stream instanceof events.EventEmitter); // true
console.log(MyStream.super_ === events.EventEmitter); // true
stream.on(&quot;data&quot;, function(data) {
console.log(&#39;Received data: &quot;&#39; + data + &#39;&quot;&#39;);
})
stream.write(&quot;It works!&quot;); // Received data: &quot;It works!&quot;</code></pre>
<h1>Events<span><a class="mark" href="#all_events" id="all_events">#</a></span></h1>
<pre class="api_stability_4">Stability: 4 - API Frozen</pre><!--type=module-->
<p>Many objects in Node emit events: a <code>net.Server</code> emits an event each time
a peer connects to it, a <code>fs.readStream</code> emits an event when the file is
opened. All objects which emit events are instances of <code>events.EventEmitter</code>.
You can access this module by doing: <code>require(&quot;events&quot;);</code>
</p>
<p>Typically, event names are represented by a camel-cased string, however,
there aren&#39;t any strict restrictions on that, as any string will be accepted.
</p>
<p>Functions can then be attached to objects, to be executed when an event
is emitted. These functions are called <em>listeners</em>. Inside a listener
function, <code>this</code> refers to the <code>EventEmitter</code> that the listener was
attached to.
</p>
<h2>Class: events.EventEmitter<span><a class="mark" href="#all_class_events_eventemitter" id="all_class_events_eventemitter">#</a></span></h2>
<p>To access the EventEmitter class, <code>require(&#39;events&#39;).EventEmitter</code>.
</p>
<p>When an <code>EventEmitter</code> instance experiences an error, the typical action is
to emit an <code>&#39;error&#39;</code> event. Error events are treated as a special case in node.
If there is no listener for it, then the default action is to print a stack
trace and exit the program.
</p>
<p>All EventEmitters emit the event <code>&#39;newListener&#39;</code> when new listeners are
added and <code>&#39;removeListener&#39;</code> when a listener is removed.
</p>
<h3>emitter.addListener(event, listener)<span><a class="mark" href="#all_emitter_addlistener_event_listener" id="all_emitter_addlistener_event_listener">#</a></span></h3>
<h3>emitter.on(event, listener)<span><a class="mark" href="#all_emitter_on_event_listener" id="all_emitter_on_event_listener">#</a></span></h3>
<p>Adds a listener to the end of the listeners array for the specified event.
</p>
<pre><code>server.on(&#39;connection&#39;, function (stream) {
console.log(&#39;someone connected!&#39;);
});</code></pre>
<p>Returns emitter, so calls can be chained.
</p>
<h3>emitter.once(event, listener)<span><a class="mark" href="#all_emitter_once_event_listener" id="all_emitter_once_event_listener">#</a></span></h3>
<p>Adds a <strong>one time</strong> listener for the event. This listener is
invoked only the next time the event is fired, after which
it is removed.
</p>
<pre><code>server.once(&#39;connection&#39;, function (stream) {
console.log(&#39;Ah, we have our first user!&#39;);
});</code></pre>
<p>Returns emitter, so calls can be chained.
</p>
<h3>emitter.removeListener(event, listener)<span><a class="mark" href="#all_emitter_removelistener_event_listener" id="all_emitter_removelistener_event_listener">#</a></span></h3>
<p>Remove a listener from the listener array for the specified event.
<strong>Caution</strong>: changes array indices in the listener array behind the listener.
</p>
<pre><code>var callback = function(stream) {
console.log(&#39;someone connected!&#39;);
};
server.on(&#39;connection&#39;, callback);
// ...
server.removeListener(&#39;connection&#39;, callback);</code></pre>
<p>Returns emitter, so calls can be chained.
</p>
<h3>emitter.removeAllListeners([event])<span><a class="mark" href="#all_emitter_removealllisteners_event" id="all_emitter_removealllisteners_event">#</a></span></h3>
<p>Removes all listeners, or those of the specified event.
</p>
<p>Returns emitter, so calls can be chained.
</p>
<h3>emitter.setMaxListeners(n)<span><a class="mark" href="#all_emitter_setmaxlisteners_n" id="all_emitter_setmaxlisteners_n">#</a></span></h3>
<p>By default EventEmitters will print a warning if more than 10 listeners are
added for a particular event. This is a useful default which helps finding memory leaks.
Obviously not all Emitters should be limited to 10. This function allows
that to be increased. Set to zero for unlimited.
</p>
<h3>emitter.listeners(event)<span><a class="mark" href="#all_emitter_listeners_event" id="all_emitter_listeners_event">#</a></span></h3>
<p>Returns an array of listeners for the specified event.
</p>
<pre><code>server.on(&#39;connection&#39;, function (stream) {
console.log(&#39;someone connected!&#39;);
});
console.log(util.inspect(server.listeners(&#39;connection&#39;))); // [ [Function] ]</code></pre>
<h3>emitter.emit(event, [arg1], [arg2], [...])<span><a class="mark" href="#all_emitter_emit_event_arg1_arg2" id="all_emitter_emit_event_arg1_arg2">#</a></span></h3>
<p>Execute each of the listeners in order with the supplied arguments.
</p>
<p>Returns <code>true</code> if event had listeners, <code>false</code> otherwise.
</p>
<h3>Class Method: EventEmitter.listenerCount(emitter, event)<span><a class="mark" href="#all_class_method_eventemitter_listenercount_emitter_event" id="all_class_method_eventemitter_listenercount_emitter_event">#</a></span></h3>
<p>Return the number of listeners for a given event.
</p>
<h3>Event: &#39;newListener&#39;<span><a class="mark" href="#all_event_newlistener" id="all_event_newlistener">#</a></span></h3>
<div class="signature"><ul>
<li><code>event</code> <span class="type">String</span> The event name</li>
<li><code>listener</code> <span class="type">Function</span> The event handler function</li>
</div></ul>
<p>This event is emitted any time someone adds a new listener. It is unspecified
if <code>listener</code> is in the list returned by <code>emitter.listeners(event)</code>.
</p>
<h3>Event: &#39;removeListener&#39;<span><a class="mark" href="#all_event_removelistener" id="all_event_removelistener">#</a></span></h3>
<div class="signature"><ul>
<li><code>event</code> <span class="type">String</span> The event name</li>
<li><code>listener</code> <span class="type">Function</span> The event handler function</li>
</div></ul>
<p>This event is emitted any time someone removes a listener. It is unspecified
if <code>listener</code> is in the list returned by <code>emitter.listeners(event)</code>.
</p>
<h1>Domain<span><a class="mark" href="#all_domain" id="all_domain">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable</pre><p>Domains provide a way to handle multiple different IO operations as a
single group. If any of the event emitters or callbacks registered to a
domain emit an <code>error</code> event, or throw an error, then the domain object
will be notified, rather than losing the context of the error in the
<code>process.on(&#39;uncaughtException&#39;)</code> handler, or causing the program to
exit immediately with an error code.
</p>
<h2>Warning: Don&#39;t Ignore Errors!<span><a class="mark" href="#all_warning_don_t_ignore_errors" id="all_warning_don_t_ignore_errors">#</a></span></h2>
<!-- type=misc -->
<p>Domain error handlers are not a substitute for closing down your
process when an error occurs.
</p>
<p>By the very nature of how <code>throw</code> works in JavaScript, there is almost
never any way to safely &quot;pick up where you left off&quot;, without leaking
references, or creating some other sort of undefined brittle state.
</p>
<p>The safest way to respond to a thrown error is to shut down the
process. Of course, in a normal web server, you might have many
connections open, and it is not reasonable to abruptly shut those down
because an error was triggered by someone else.
</p>
<p>The better approach is send an error response to the request that
triggered the error, while letting the others finish in their normal
time, and stop listening for new requests in that worker.
</p>
<p>In this way, <code>domain</code> usage goes hand-in-hand with the cluster module,
since the master process can fork a new worker when a worker
encounters an error. For node programs that scale to multiple
machines, the terminating proxy or service registry can take note of
the failure, and react accordingly.
</p>
<p>For example, this is not a good idea:
</p>
<pre><code class="javascript">// XXX WARNING! BAD IDEA!
var d = require(&#39;domain&#39;).create();
d.on(&#39;error&#39;, function(er) {
// The error won&#39;t crash the process, but what it does is worse!
// Though we&#39;ve prevented abrupt process restarting, we are leaking
// resources like crazy if this ever happens.
// This is no better than process.on(&#39;uncaughtException&#39;)!
console.log(&#39;error, but oh well&#39;, er.message);
});
d.run(function() {
require(&#39;http&#39;).createServer(function(req, res) {
handleRequest(req, res);
}).listen(PORT);
});</code></pre>
<p>By using the context of a domain, and the resilience of separating our
program into multiple worker processes, we can react more
appropriately, and handle errors with much greater safety.
</p>
<pre><code class="javascript">// Much better!
var cluster = require(&#39;cluster&#39;);
var PORT = +process.env.PORT || 1337;
if (cluster.isMaster) {
// In real life, you&#39;d probably use more than just 2 workers,
// and perhaps not put the master and worker in the same file.
//
// You can also of course get a bit fancier about logging, and
// implement whatever custom logic you need to prevent DoS
// attacks and other bad behavior.
//
// See the options in the cluster documentation.
//
// The important thing is that the master does very little,
// increasing our resilience to unexpected errors.
cluster.fork();
cluster.fork();
cluster.on(&#39;disconnect&#39;, function(worker) {
console.error(&#39;disconnect!&#39;);
cluster.fork();
});
} else {
// the worker
//
// This is where we put our bugs!
var domain = require(&#39;domain&#39;);
// See the cluster documentation for more details about using
// worker processes to serve requests. How it works, caveats, etc.
var server = require(&#39;http&#39;).createServer(function(req, res) {
var d = domain.create();
d.on(&#39;error&#39;, function(er) {
console.error(&#39;error&#39;, er.stack);
// Note: we&#39;re in dangerous territory!
// By definition, something unexpected occurred,
// which we probably didn&#39;t want.
// Anything can happen now! Be very careful!
try {
// make sure we close down within 30 seconds
var killtimer = setTimeout(function() {
process.exit(1);
}, 30000);
// But don&#39;t keep the process open just for that!
killtimer.unref();
// stop taking new requests.
server.close();
// Let the master know we&#39;re dead. This will trigger a
// &#39;disconnect&#39; in the cluster master, and then it will fork
// a new worker.
cluster.worker.disconnect();
// try to send an error to the request that triggered the problem
res.statusCode = 500;
res.setHeader(&#39;content-type&#39;, &#39;text/plain&#39;);
res.end(&#39;Oops, there was a problem!\n&#39;);
} catch (er2) {
// oh well, not much we can do at this point.
console.error(&#39;Error sending 500!&#39;, er2.stack);
}
});
// Because req and res were created before this domain existed,
// we need to explicitly add them.
// See the explanation of implicit vs explicit binding below.
d.add(req);
d.add(res);
// Now run the handler function in the domain.
d.run(function() {
handleRequest(req, res);
});
});
server.listen(PORT);
}
// This part isn&#39;t important. Just an example routing thing.
// You&#39;d put your fancy application logic here.
function handleRequest(req, res) {
switch(req.url) {
case &#39;/error&#39;:
// We do some async stuff, and then...
setTimeout(function() {
// Whoops!
flerb.bark();
});
break;
default:
res.end(&#39;ok&#39;);
}
}</code></pre>
<h2>Additions to Error objects<span><a class="mark" href="#all_additions_to_error_objects" id="all_additions_to_error_objects">#</a></span></h2>
<!-- type=misc -->
<p>Any time an Error object is routed through a domain, a few extra fields
are added to it.
</p>
<ul>
<li><code>error.domain</code> The domain that first handled the error.</li>
<li><code>error.domainEmitter</code> The event emitter that emitted an &#39;error&#39; event
with the error object.</li>
<li><code>error.domainBound</code> The callback function which was bound to the
domain, and passed an error as its first argument.</li>
<li><code>error.domainThrown</code> A boolean indicating whether the error was
thrown, emitted, or passed to a bound callback function.</li>
</ul>
<h2>Implicit Binding<span><a class="mark" href="#all_implicit_binding" id="all_implicit_binding">#</a></span></h2>
<!--type=misc-->
<p>If domains are in use, then all <strong>new</strong> EventEmitter objects (including
Stream objects, requests, responses, etc.) will be implicitly bound to
the active domain at the time of their creation.
</p>
<p>Additionally, callbacks passed to lowlevel event loop requests (such as
to fs.open, or other callback-taking methods) will automatically be
bound to the active domain. If they throw, then the domain will catch
the error.
</p>
<p>In order to prevent excessive memory usage, Domain objects themselves
are not implicitly added as children of the active domain. If they
were, then it would be too easy to prevent request and response objects
from being properly garbage collected.
</p>
<p>If you <em>want</em> to nest Domain objects as children of a parent Domain,
then you must explicitly add them.
</p>
<p>Implicit binding routes thrown errors and <code>&#39;error&#39;</code> events to the
Domain&#39;s <code>error</code> event, but does not register the EventEmitter on the
Domain, so <code>domain.dispose()</code> will not shut down the EventEmitter.
Implicit binding only takes care of thrown errors and <code>&#39;error&#39;</code> events.
</p>
<h2>Explicit Binding<span><a class="mark" href="#all_explicit_binding" id="all_explicit_binding">#</a></span></h2>
<!--type=misc-->
<p>Sometimes, the domain in use is not the one that ought to be used for a
specific event emitter. Or, the event emitter could have been created
in the context of one domain, but ought to instead be bound to some
other domain.
</p>
<p>For example, there could be one domain in use for an HTTP server, but
perhaps we would like to have a separate domain to use for each request.
</p>
<p>That is possible via explicit binding.
</p>
<p>For example:
</p>
<pre><code>// create a top-level domain for the server
var serverDomain = domain.create();
serverDomain.run(function() {
// server is created in the scope of serverDomain
http.createServer(function(req, res) {
// req and res are also created in the scope of serverDomain
// however, we&#39;d prefer to have a separate domain for each request.
// create it first thing, and add req and res to it.
var reqd = domain.create();
reqd.add(req);
reqd.add(res);
reqd.on(&#39;error&#39;, function(er) {
console.error(&#39;Error&#39;, er, req.url);
try {
res.writeHead(500);
res.end(&#39;Error occurred, sorry.&#39;);
} catch (er) {
console.error(&#39;Error sending 500&#39;, er, req.url);
}
});
}).listen(1337);
});</code></pre>
<h2>domain.create()<span><a class="mark" href="#all_domain_create" id="all_domain_create">#</a></span></h2>
<div class="signature"><ul>
<li>return: <span class="type">Domain</span></li>
</div></ul>
<p>Returns a new Domain object.
</p>
<h2>Class: Domain<span><a class="mark" href="#all_class_domain" id="all_class_domain">#</a></span></h2>
<p>The Domain class encapsulates the functionality of routing errors and
uncaught exceptions to the active Domain object.
</p>
<p>Domain is a child class of <a href="events.html#events_class_events_eventemitter">EventEmitter</a>. To handle the errors that it
catches, listen to its <code>error</code> event.
</p>
<h3>domain.run(fn)<span><a class="mark" href="#all_domain_run_fn" id="all_domain_run_fn">#</a></span></h3>
<div class="signature"><ul>
<li><code>fn</code> <span class="type">Function</span></li>
</div></ul>
<p>Run the supplied function in the context of the domain, implicitly
binding all event emitters, timers, and lowlevel requests that are
created in that context.
</p>
<p>This is the most basic way to use a domain.
</p>
<p>Example:
</p>
<pre><code>var d = domain.create();
d.on(&#39;error&#39;, function(er) {
console.error(&#39;Caught error!&#39;, er);
});
d.run(function() {
process.nextTick(function() {
setTimeout(function() { // simulating some various async stuff
fs.open(&#39;non-existent file&#39;, &#39;r&#39;, function(er, fd) {
if (er) throw er;
// proceed...
});
}, 100);
});
});</code></pre>
<p>In this example, the <code>d.on(&#39;error&#39;)</code> handler will be triggered, rather
than crashing the program.
</p>
<h3>domain.members<span><a class="mark" href="#all_domain_members" id="all_domain_members">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Array</span></li>
</div></ul>
<p>An array of timers and event emitters that have been explicitly added
to the domain.
</p>
<h3>domain.add(emitter)<span><a class="mark" href="#all_domain_add_emitter" id="all_domain_add_emitter">#</a></span></h3>
<div class="signature"><ul>
<li><code>emitter</code> <span class="type">EventEmitter | Timer</span> emitter or timer to be added to the domain</li>
</div></ul>
<p>Explicitly adds an emitter to the domain. If any event handlers called by
the emitter throw an error, or if the emitter emits an <code>error</code> event, it
will be routed to the domain&#39;s <code>error</code> event, just like with implicit
binding.
</p>
<p>This also works with timers that are returned from <code>setInterval</code> and
<code>setTimeout</code>. If their callback function throws, it will be caught by
the domain &#39;error&#39; handler.
</p>
<p>If the Timer or EventEmitter was already bound to a domain, it is removed
from that one, and bound to this one instead.
</p>
<h3>domain.remove(emitter)<span><a class="mark" href="#all_domain_remove_emitter" id="all_domain_remove_emitter">#</a></span></h3>
<div class="signature"><ul>
<li><code>emitter</code> <span class="type">EventEmitter | Timer</span> emitter or timer to be removed from the domain</li>
</div></ul>
<p>The opposite of <code>domain.add(emitter)</code>. Removes domain handling from the
specified emitter.
</p>
<h3>domain.bind(callback)<span><a class="mark" href="#all_domain_bind_callback" id="all_domain_bind_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>callback</code> <span class="type">Function</span> The callback function</li>
<li>return: <span class="type">Function</span> The bound function</li>
</div></ul>
<p>The returned function will be a wrapper around the supplied callback
function. When the returned function is called, any errors that are
thrown will be routed to the domain&#39;s <code>error</code> event.
</p>
<h4>Example<span><a class="mark" href="#all_example" id="all_example">#</a></span></h4>
<pre><code>var d = domain.create();
function readSomeFile(filename, cb) {
fs.readFile(filename, &#39;utf8&#39;, d.bind(function(er, data) {
// if this throws, it will also be passed to the domain
return cb(er, data ? JSON.parse(data) : null);
}));
}
d.on(&#39;error&#39;, function(er) {
// an error occurred somewhere.
// if we throw it now, it will crash the program
// with the normal line number and stack message.
});</code></pre>
<h3>domain.intercept(callback)<span><a class="mark" href="#all_domain_intercept_callback" id="all_domain_intercept_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>callback</code> <span class="type">Function</span> The callback function</li>
<li>return: <span class="type">Function</span> The intercepted function</li>
</div></ul>
<p>This method is almost identical to <code>domain.bind(callback)</code>. However, in
addition to catching thrown errors, it will also intercept <code>Error</code>
objects sent as the first argument to the function.
</p>
<p>In this way, the common <code>if (er) return callback(er);</code> pattern can be replaced
with a single error handler in a single place.
</p>
<h4>Example<span><a class="mark" href="#all_example_1" id="all_example_1">#</a></span></h4>
<pre><code>var d = domain.create();
function readSomeFile(filename, cb) {
fs.readFile(filename, &#39;utf8&#39;, d.intercept(function(data) {
// note, the first argument is never passed to the
// callback since it is assumed to be the &#39;Error&#39; argument
// and thus intercepted by the domain.
// if this throws, it will also be passed to the domain
// so the error-handling logic can be moved to the &#39;error&#39;
// event on the domain instead of being repeated throughout
// the program.
return cb(null, JSON.parse(data));
}));
}
d.on(&#39;error&#39;, function(er) {
// an error occurred somewhere.
// if we throw it now, it will crash the program
// with the normal line number and stack message.
});</code></pre>
<h3>domain.enter()<span><a class="mark" href="#all_domain_enter" id="all_domain_enter">#</a></span></h3>
<p>The <code>enter</code> method is plumbing used by the <code>run</code>, <code>bind</code>, and <code>intercept</code>
methods to set the active domain. It sets <code>domain.active</code> and <code>process.domain</code>
to the domain, and implicitly pushes the domain onto the domain stack managed
by the domain module (see <code>domain.exit()</code> for details on the domain stack). The
call to <code>enter</code> delimits the beginning of a chain of asynchronous calls and I/O
operations bound to a domain.
</p>
<p>Calling <code>enter</code> changes only the active domain, and does not alter the domain
itself. <code>Enter</code> and <code>exit</code> can be called an arbitrary number of times on a
single domain.
</p>
<p>If the domain on which <code>enter</code> is called has been disposed, <code>enter</code> will return
without setting the domain.
</p>
<h3>domain.exit()<span><a class="mark" href="#all_domain_exit" id="all_domain_exit">#</a></span></h3>
<p>The <code>exit</code> method exits the current domain, popping it off the domain stack.
Any time execution is going to switch to the context of a different chain of
asynchronous calls, it&#39;s important to ensure that the current domain is exited.
The call to <code>exit</code> delimits either the end of or an interruption to the chain
of asynchronous calls and I/O operations bound to a domain.
</p>
<p>If there are multiple, nested domains bound to the current execution context,
<code>exit</code> will exit any domains nested within this domain.
</p>
<p>Calling <code>exit</code> changes only the active domain, and does not alter the domain
itself. <code>Enter</code> and <code>exit</code> can be called an arbitrary number of times on a
single domain.
</p>
<p>If the domain on which <code>exit</code> is called has been disposed, <code>exit</code> will return
without exiting the domain.
</p>
<h3>domain.dispose()<span><a class="mark" href="#all_domain_dispose" id="all_domain_dispose">#</a></span></h3>
<p>The dispose method destroys a domain, and makes a best effort attempt to
clean up any and all IO that is associated with the domain. Streams are
aborted, ended, closed, and/or destroyed. Timers are cleared.
Explicitly bound callbacks are no longer called. Any error events that
are raised as a result of this are ignored.
</p>
<p>The intention of calling <code>dispose</code> is generally to prevent cascading
errors when a critical part of the Domain context is found to be in an
error state.
</p>
<p>Once the domain is disposed the <code>dispose</code> event will emit.
</p>
<p>Note that IO might still be performed. However, to the highest degree
possible, once a domain is disposed, further errors from the emitters in
that set will be ignored. So, even if some remaining actions are still
in flight, Node.js will not communicate further about them.
</p>
<h1>Buffer<span><a class="mark" href="#all_buffer" id="all_buffer">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>Pure JavaScript is Unicode friendly but not nice to binary data. When
dealing with TCP streams or the file system, it&#39;s necessary to handle octet
streams. Node has several strategies for manipulating, creating, and
consuming octet streams.
</p>
<p>Raw data is stored in instances of the <code>Buffer</code> class. A <code>Buffer</code> is similar
to an array of integers but corresponds to a raw memory allocation outside
the V8 heap. A <code>Buffer</code> cannot be resized.
</p>
<p>The <code>Buffer</code> class is a global, making it very rare that one would need
to ever <code>require(&#39;buffer&#39;)</code>.
</p>
<p>Converting between Buffers and JavaScript string objects requires an explicit
encoding method. Here are the different string encodings.
</p>
<ul>
<li><p><code>&#39;ascii&#39;</code> - for 7 bit ASCII data only. This encoding method is very fast, and
will strip the high bit if set.</p>
<p>Note that when converting from string to buffer, this encoding converts a null
character (<code>&#39;\0&#39;</code> or <code>&#39;\u0000&#39;</code>) into <code>0x20</code> (character code of a space). If
you want to convert a null character into <code>0x00</code>, you should use <code>&#39;utf8&#39;</code>.</p>
</li>
<li><p><code>&#39;utf8&#39;</code> - Multibyte encoded Unicode characters. Many web pages and other
document formats use UTF-8.</p>
</li>
<li><p><code>&#39;utf16le&#39;</code> - 2 or 4 bytes, little endian encoded Unicode characters.
Surrogate pairs (U+10000 to U+10FFFF) are supported.</p>
</li>
<li><p><code>&#39;ucs2&#39;</code> - Alias of <code>&#39;utf16le&#39;</code>.</p>
</li>
<li><p><code>&#39;base64&#39;</code> - Base64 string encoding.</p>
</li>
<li><p><code>&#39;binary&#39;</code> - A way of encoding raw binary data into strings by using only
the first 8 bits of each character. This encoding method is deprecated and
should be avoided in favor of <code>Buffer</code> objects where possible. This encoding
will be removed in future versions of Node.</p>
</li>
<li><p><code>&#39;hex&#39;</code> - Encode each byte as two hexadecimal characters.</p>
</li>
</ul>
<p>A <code>Buffer</code> object can also be used with typed arrays. The buffer object is
cloned to an <code>ArrayBuffer</code> that is used as the backing store for the typed
array. The memory of the buffer and the <code>ArrayBuffer</code> is not shared.
</p>
<p>NOTE: Node.js v0.8 simply retained a reference to the buffer in <code>array.buffer</code>
instead of cloning it.
</p>
<p>While more efficient, it introduces subtle incompatibilities with the typed
arrays specification. <code>ArrayBuffer#slice()</code> makes a copy of the slice while
<code>Buffer#slice()</code> creates a view.
</p>
<h2>Class: Buffer<span><a class="mark" href="#all_class_buffer_1" id="all_class_buffer_1">#</a></span></h2>
<p>The Buffer class is a global type for dealing with binary data directly.
It can be constructed in a variety of ways.
</p>
<h3>new Buffer(size)<span><a class="mark" href="#all_new_buffer_size" id="all_new_buffer_size">#</a></span></h3>
<div class="signature"><ul>
<li><code>size</code> Number</li>
</div></ul>
<p>Allocates a new buffer of <code>size</code> octets.
</p>
<h3>new Buffer(array)<span><a class="mark" href="#all_new_buffer_array" id="all_new_buffer_array">#</a></span></h3>
<div class="signature"><ul>
<li><code>array</code> Array</li>
</div></ul>
<p>Allocates a new buffer using an <code>array</code> of octets.
</p>
<h3>new Buffer(str, [encoding])<span><a class="mark" href="#all_new_buffer_str_encoding" id="all_new_buffer_str_encoding">#</a></span></h3>
<div class="signature"><ul>
<li><code>str</code> String - string to encode.</li>
<li><code>encoding</code> String - encoding to use, Optional.</li>
</div></ul>
<p>Allocates a new buffer containing the given <code>str</code>.
<code>encoding</code> defaults to <code>&#39;utf8&#39;</code>.
</p>
<h3>Class Method: Buffer.isEncoding(encoding)<span><a class="mark" href="#all_class_method_buffer_isencoding_encoding" id="all_class_method_buffer_isencoding_encoding">#</a></span></h3>
<div class="signature"><ul>
<li><code>encoding</code> <span class="type">String</span> The encoding string to test</li>
</div></ul>
<p>Returns true if the <code>encoding</code> is a valid encoding argument, or false
otherwise.
</p>
<h3>buf.write(string, [offset], [length], [encoding])<span><a class="mark" href="#all_buf_write_string_offset_length_encoding" id="all_buf_write_string_offset_length_encoding">#</a></span></h3>
<div class="signature"><ul>
<li><code>string</code> String - data to be written to buffer</li>
<li><code>offset</code> Number, Optional, Default: 0</li>
<li><code>length</code> Number, Optional, Default: <code>buffer.length - offset</code></li>
<li><code>encoding</code> String, Optional, Default: &#39;utf8&#39;</li>
</div></ul>
<p>Writes <code>string</code> to the buffer at <code>offset</code> using the given encoding.
<code>offset</code> defaults to <code>0</code>, <code>encoding</code> defaults to <code>&#39;utf8&#39;</code>. <code>length</code> is
the number of bytes to write. Returns number of octets written. If <code>buffer</code> did
not contain enough space to fit the entire string, it will write a partial
amount of the string. <code>length</code> defaults to <code>buffer.length - offset</code>.
The method will not write partial characters.
</p>
<pre><code>buf = new Buffer(256);
len = buf.write(&#39;\u00bd + \u00bc = \u00be&#39;, 0);
console.log(len + &quot; bytes: &quot; + buf.toString(&#39;utf8&#39;, 0, len));</code></pre>
<p>The number of characters written (which may be different than the number of
bytes written) is set in <code>Buffer._charsWritten</code> and will be overwritten the
next time <code>buf.write()</code> is called.
</p>
<h3>buf.toString([encoding], [start], [end])<span><a class="mark" href="#all_buf_tostring_encoding_start_end" id="all_buf_tostring_encoding_start_end">#</a></span></h3>
<div class="signature"><ul>
<li><code>encoding</code> String, Optional, Default: &#39;utf8&#39;</li>
<li><code>start</code> Number, Optional, Default: 0</li>
<li><code>end</code> Number, Optional, Default: <code>buffer.length</code></li>
</div></ul>
<p>Decodes and returns a string from buffer data encoded with <code>encoding</code>
(defaults to <code>&#39;utf8&#39;</code>) beginning at <code>start</code> (defaults to <code>0</code>) and ending at
<code>end</code> (defaults to <code>buffer.length</code>).
</p>
<p>See <code>buffer.write()</code> example, above.
</p>
<h3>buf.toJSON()<span><a class="mark" href="#all_buf_tojson" id="all_buf_tojson">#</a></span></h3>
<p>Returns a JSON-representation of the Buffer instance, which is identical to the
output for JSON Arrays. <code>JSON.stringify</code> implicitly calls this function when
stringifying a Buffer instance.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(&#39;test&#39;);
var json = JSON.stringify(buf);
console.log(json);
// &#39;[116,101,115,116]&#39;
var copy = new Buffer(JSON.parse(json));
console.log(copy);
// &lt;Buffer 74 65 73 74&gt;</code></pre>
<h3>buf[index]<span><a class="mark" href="#all_buf_index" id="all_buf_index">#</a></span></h3>
<!--type=property-->
<!--name=[index]-->
<p>Get and set the octet at <code>index</code>. The values refer to individual bytes,
so the legal range is between <code>0x00</code> and <code>0xFF</code> hex or <code>0</code> and <code>255</code>.
</p>
<p>Example: copy an ASCII string into a buffer, one byte at a time:
</p>
<pre><code>str = &quot;node.js&quot;;
buf = new Buffer(str.length);
for (var i = 0; i &lt; str.length ; i++) {
buf[i] = str.charCodeAt(i);
}
console.log(buf);
// node.js</code></pre>
<h3>Class Method: Buffer.isBuffer(obj)<span><a class="mark" href="#all_class_method_buffer_isbuffer_obj" id="all_class_method_buffer_isbuffer_obj">#</a></span></h3>
<div class="signature"><ul>
<li><code>obj</code> Object</li>
<li>Return: Boolean</li>
</div></ul>
<p>Tests if <code>obj</code> is a <code>Buffer</code>.
</p>
<h3>Class Method: Buffer.byteLength(string, [encoding])<span><a class="mark" href="#all_class_method_buffer_bytelength_string_encoding" id="all_class_method_buffer_bytelength_string_encoding">#</a></span></h3>
<div class="signature"><ul>
<li><code>string</code> String</li>
<li><code>encoding</code> String, Optional, Default: &#39;utf8&#39;</li>
<li>Return: Number</li>
</div></ul>
<p>Gives the actual byte length of a string. <code>encoding</code> defaults to <code>&#39;utf8&#39;</code>.
This is not the same as <code>String.prototype.length</code> since that returns the
number of <em>characters</em> in a string.
</p>
<p>Example:
</p>
<pre><code>str = &#39;\u00bd + \u00bc = \u00be&#39;;
console.log(str + &quot;: &quot; + str.length + &quot; characters, &quot; +
Buffer.byteLength(str, &#39;utf8&#39;) + &quot; bytes&quot;);
// ½ + ¼ = ¾: 9 characters, 12 bytes</code></pre>
<h3>Class Method: Buffer.concat(list, [totalLength])<span><a class="mark" href="#all_class_method_buffer_concat_list_totallength" id="all_class_method_buffer_concat_list_totallength">#</a></span></h3>
<div class="signature"><ul>
<li><code>list</code> <span class="type">Array</span> List of Buffer objects to concat</li>
<li><code>totalLength</code> <span class="type">Number</span> Total length of the buffers when concatenated</li>
</div></ul>
<p>Returns a buffer which is the result of concatenating all the buffers in
the list together.
</p>
<p>If the list has no items, or if the totalLength is 0, then it returns a
zero-length buffer.
</p>
<p>If the list has exactly one item, then the first item of the list is
returned.
</p>
<p>If the list has more than one item, then a new Buffer is created.
</p>
<p>If totalLength is not provided, it is read from the buffers in the list.
However, this adds an additional loop to the function, so it is faster
to provide the length explicitly.
</p>
<h3>buf.length<span><a class="mark" href="#all_buf_length" id="all_buf_length">#</a></span></h3>
<div class="signature"><ul>
<li>Number</li>
</div></ul>
<p>The size of the buffer in bytes. Note that this is not necessarily the size
of the contents. <code>length</code> refers to the amount of memory allocated for the
buffer object. It does not change when the contents of the buffer are changed.
</p>
<pre><code>buf = new Buffer(1234);
console.log(buf.length);
buf.write(&quot;some string&quot;, 0, &quot;ascii&quot;);
console.log(buf.length);
// 1234
// 1234</code></pre>
<h3>buf.copy(targetBuffer, [targetStart], [sourceStart], [sourceEnd])<span><a class="mark" href="#all_buf_copy_targetbuffer_targetstart_sourcestart_sourceend" id="all_buf_copy_targetbuffer_targetstart_sourcestart_sourceend">#</a></span></h3>
<div class="signature"><ul>
<li><code>targetBuffer</code> Buffer object - Buffer to copy into</li>
<li><code>targetStart</code> Number, Optional, Default: 0</li>
<li><code>sourceStart</code> Number, Optional, Default: 0</li>
<li><code>sourceEnd</code> Number, Optional, Default: <code>buffer.length</code></li>
</div></ul>
<p>Does copy between buffers. The source and target regions can be overlapped.
<code>targetStart</code> and <code>sourceStart</code> default to <code>0</code>.
<code>sourceEnd</code> defaults to <code>buffer.length</code>.
</p>
<p>All values passed that are <code>undefined</code>/<code>NaN</code> or are out of bounds are set equal
to their respective defaults.
</p>
<p>Example: build two Buffers, then copy <code>buf1</code> from byte 16 through byte 19
into <code>buf2</code>, starting at the 8th byte in <code>buf2</code>.
</p>
<pre><code>buf1 = new Buffer(26);
buf2 = new Buffer(26);
for (var i = 0 ; i &lt; 26 ; i++) {
buf1[i] = i + 97; // 97 is ASCII a
buf2[i] = 33; // ASCII !
}
buf1.copy(buf2, 8, 16, 20);
console.log(buf2.toString(&#39;ascii&#39;, 0, 25));
// !!!!!!!!qrst!!!!!!!!!!!!!</code></pre>
<h3>buf.slice([start], [end])<span><a class="mark" href="#all_buf_slice_start_end" id="all_buf_slice_start_end">#</a></span></h3>
<div class="signature"><ul>
<li><code>start</code> Number, Optional, Default: 0</li>
<li><code>end</code> Number, Optional, Default: <code>buffer.length</code></li>
</div></ul>
<p>Returns a new buffer which references the same memory as the old, but offset
and cropped by the <code>start</code> (defaults to <code>0</code>) and <code>end</code> (defaults to
<code>buffer.length</code>) indexes. Negative indexes start from the end of the buffer.
</p>
<p><strong>Modifying the new buffer slice will modify memory in the original buffer!</strong>
</p>
<p>Example: build a Buffer with the ASCII alphabet, take a slice, then modify one
byte from the original Buffer.
</p>
<pre><code>var buf1 = new Buffer(26);
for (var i = 0 ; i &lt; 26 ; i++) {
buf1[i] = i + 97; // 97 is ASCII a
}
var buf2 = buf1.slice(0, 3);
console.log(buf2.toString(&#39;ascii&#39;, 0, buf2.length));
buf1[0] = 33;
console.log(buf2.toString(&#39;ascii&#39;, 0, buf2.length));
// abc
// !bc</code></pre>
<h3>buf.readUInt8(offset, [noAssert])<span><a class="mark" href="#all_buf_readuint8_offset_noassert" id="all_buf_readuint8_offset_noassert">#</a></span></h3>
<div class="signature"><ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</div></ul>
<p>Reads an unsigned 8 bit integer from the buffer at the specified offset.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf[0] = 0x3;
buf[1] = 0x4;
buf[2] = 0x23;
buf[3] = 0x42;
for (ii = 0; ii &lt; buf.length; ii++) {
console.log(buf.readUInt8(ii));
}
// 0x3
// 0x4
// 0x23
// 0x42</code></pre>
<h3>buf.readUInt16LE(offset, [noAssert])<span><a class="mark" href="#all_buf_readuint16le_offset_noassert" id="all_buf_readuint16le_offset_noassert">#</a></span></h3>
<h3>buf.readUInt16BE(offset, [noAssert])<span><a class="mark" href="#all_buf_readuint16be_offset_noassert" id="all_buf_readuint16be_offset_noassert">#</a></span></h3>
<ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</ul>
<p>Reads an unsigned 16 bit integer from the buffer at the specified offset with
specified endian format.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf[0] = 0x3;
buf[1] = 0x4;
buf[2] = 0x23;
buf[3] = 0x42;
console.log(buf.readUInt16BE(0));
console.log(buf.readUInt16LE(0));
console.log(buf.readUInt16BE(1));
console.log(buf.readUInt16LE(1));
console.log(buf.readUInt16BE(2));
console.log(buf.readUInt16LE(2));
// 0x0304
// 0x0403
// 0x0423
// 0x2304
// 0x2342
// 0x4223</code></pre>
<h3>buf.readUInt32LE(offset, [noAssert])<span><a class="mark" href="#all_buf_readuint32le_offset_noassert" id="all_buf_readuint32le_offset_noassert">#</a></span></h3>
<h3>buf.readUInt32BE(offset, [noAssert])<span><a class="mark" href="#all_buf_readuint32be_offset_noassert" id="all_buf_readuint32be_offset_noassert">#</a></span></h3>
<ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</ul>
<p>Reads an unsigned 32 bit integer from the buffer at the specified offset with
specified endian format.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf[0] = 0x3;
buf[1] = 0x4;
buf[2] = 0x23;
buf[3] = 0x42;
console.log(buf.readUInt32BE(0));
console.log(buf.readUInt32LE(0));
// 0x03042342
// 0x42230403</code></pre>
<h3>buf.readInt8(offset, [noAssert])<span><a class="mark" href="#all_buf_readint8_offset_noassert" id="all_buf_readint8_offset_noassert">#</a></span></h3>
<div class="signature"><ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</div></ul>
<p>Reads a signed 8 bit integer from the buffer at the specified offset.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Works as <code>buffer.readUInt8</code>, except buffer contents are treated as two&#39;s
complement signed values.
</p>
<h3>buf.readInt16LE(offset, [noAssert])<span><a class="mark" href="#all_buf_readint16le_offset_noassert" id="all_buf_readint16le_offset_noassert">#</a></span></h3>
<h3>buf.readInt16BE(offset, [noAssert])<span><a class="mark" href="#all_buf_readint16be_offset_noassert" id="all_buf_readint16be_offset_noassert">#</a></span></h3>
<ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</ul>
<p>Reads a signed 16 bit integer from the buffer at the specified offset with
specified endian format.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Works as <code>buffer.readUInt16*</code>, except buffer contents are treated as two&#39;s
complement signed values.
</p>
<h3>buf.readInt32LE(offset, [noAssert])<span><a class="mark" href="#all_buf_readint32le_offset_noassert" id="all_buf_readint32le_offset_noassert">#</a></span></h3>
<h3>buf.readInt32BE(offset, [noAssert])<span><a class="mark" href="#all_buf_readint32be_offset_noassert" id="all_buf_readint32be_offset_noassert">#</a></span></h3>
<ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</ul>
<p>Reads a signed 32 bit integer from the buffer at the specified offset with
specified endian format.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Works as <code>buffer.readUInt32*</code>, except buffer contents are treated as two&#39;s
complement signed values.
</p>
<h3>buf.readFloatLE(offset, [noAssert])<span><a class="mark" href="#all_buf_readfloatle_offset_noassert" id="all_buf_readfloatle_offset_noassert">#</a></span></h3>
<h3>buf.readFloatBE(offset, [noAssert])<span><a class="mark" href="#all_buf_readfloatbe_offset_noassert" id="all_buf_readfloatbe_offset_noassert">#</a></span></h3>
<ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</ul>
<p>Reads a 32 bit float from the buffer at the specified offset with specified
endian format.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf[0] = 0x00;
buf[1] = 0x00;
buf[2] = 0x80;
buf[3] = 0x3f;
console.log(buf.readFloatLE(0));
// 0x01</code></pre>
<h3>buf.readDoubleLE(offset, [noAssert])<span><a class="mark" href="#all_buf_readdoublele_offset_noassert" id="all_buf_readdoublele_offset_noassert">#</a></span></h3>
<h3>buf.readDoubleBE(offset, [noAssert])<span><a class="mark" href="#all_buf_readdoublebe_offset_noassert" id="all_buf_readdoublebe_offset_noassert">#</a></span></h3>
<ul>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
<li>Return: Number</li>
</ul>
<p>Reads a 64 bit double from the buffer at the specified offset with specified
endian format.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>offset</code>. This means that <code>offset</code>
may be beyond the end of the buffer. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(8);
buf[0] = 0x55;
buf[1] = 0x55;
buf[2] = 0x55;
buf[3] = 0x55;
buf[4] = 0x55;
buf[5] = 0x55;
buf[6] = 0xd5;
buf[7] = 0x3f;
console.log(buf.readDoubleLE(0));
// 0.3333333333333333</code></pre>
<h3>buf.writeUInt8(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeuint8_value_offset_noassert" id="all_buf_writeuint8_value_offset_noassert">#</a></span></h3>
<div class="signature"><ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</div></ul>
<p>Writes <code>value</code> to the buffer at the specified offset. Note, <code>value</code> must be a
valid unsigned 8 bit integer.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf.writeUInt8(0x3, 0);
buf.writeUInt8(0x4, 1);
buf.writeUInt8(0x23, 2);
buf.writeUInt8(0x42, 3);
console.log(buf);
// &lt;Buffer 03 04 23 42&gt;</code></pre>
<h3>buf.writeUInt16LE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeuint16le_value_offset_noassert" id="all_buf_writeuint16le_value_offset_noassert">#</a></span></h3>
<h3>buf.writeUInt16BE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeuint16be_value_offset_noassert" id="all_buf_writeuint16be_value_offset_noassert">#</a></span></h3>
<ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</ul>
<p>Writes <code>value</code> to the buffer at the specified offset with specified endian
format. Note, <code>value</code> must be a valid unsigned 16 bit integer.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf.writeUInt16BE(0xdead, 0);
buf.writeUInt16BE(0xbeef, 2);
console.log(buf);
buf.writeUInt16LE(0xdead, 0);
buf.writeUInt16LE(0xbeef, 2);
console.log(buf);
// &lt;Buffer de ad be ef&gt;
// &lt;Buffer ad de ef be&gt;</code></pre>
<h3>buf.writeUInt32LE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeuint32le_value_offset_noassert" id="all_buf_writeuint32le_value_offset_noassert">#</a></span></h3>
<h3>buf.writeUInt32BE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeuint32be_value_offset_noassert" id="all_buf_writeuint32be_value_offset_noassert">#</a></span></h3>
<ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</ul>
<p>Writes <code>value</code> to the buffer at the specified offset with specified endian
format. Note, <code>value</code> must be a valid unsigned 32 bit integer.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf.writeUInt32BE(0xfeedface, 0);
console.log(buf);
buf.writeUInt32LE(0xfeedface, 0);
console.log(buf);
// &lt;Buffer fe ed fa ce&gt;
// &lt;Buffer ce fa ed fe&gt;</code></pre>
<h3>buf.writeInt8(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeint8_value_offset_noassert" id="all_buf_writeint8_value_offset_noassert">#</a></span></h3>
<div class="signature"><ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</div></ul>
<p>Writes <code>value</code> to the buffer at the specified offset. Note, <code>value</code> must be a
valid signed 8 bit integer.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Works as <code>buffer.writeUInt8</code>, except value is written out as a two&#39;s complement
signed integer into <code>buffer</code>.
</p>
<h3>buf.writeInt16LE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeint16le_value_offset_noassert" id="all_buf_writeint16le_value_offset_noassert">#</a></span></h3>
<h3>buf.writeInt16BE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeint16be_value_offset_noassert" id="all_buf_writeint16be_value_offset_noassert">#</a></span></h3>
<ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</ul>
<p>Writes <code>value</code> to the buffer at the specified offset with specified endian
format. Note, <code>value</code> must be a valid signed 16 bit integer.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Works as <code>buffer.writeUInt16*</code>, except value is written out as a two&#39;s
complement signed integer into <code>buffer</code>.
</p>
<h3>buf.writeInt32LE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeint32le_value_offset_noassert" id="all_buf_writeint32le_value_offset_noassert">#</a></span></h3>
<h3>buf.writeInt32BE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writeint32be_value_offset_noassert" id="all_buf_writeint32be_value_offset_noassert">#</a></span></h3>
<ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</ul>
<p>Writes <code>value</code> to the buffer at the specified offset with specified endian
format. Note, <code>value</code> must be a valid signed 32 bit integer.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Works as <code>buffer.writeUInt32*</code>, except value is written out as a two&#39;s
complement signed integer into <code>buffer</code>.
</p>
<h3>buf.writeFloatLE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writefloatle_value_offset_noassert" id="all_buf_writefloatle_value_offset_noassert">#</a></span></h3>
<h3>buf.writeFloatBE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writefloatbe_value_offset_noassert" id="all_buf_writefloatbe_value_offset_noassert">#</a></span></h3>
<ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</ul>
<p>Writes <code>value</code> to the buffer at the specified offset with specified endian
format. Note, behavior is unspecified if <code>value</code> is not a 32 bit float.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(4);
buf.writeFloatBE(0xcafebabe, 0);
console.log(buf);
buf.writeFloatLE(0xcafebabe, 0);
console.log(buf);
// &lt;Buffer 4f 4a fe bb&gt;
// &lt;Buffer bb fe 4a 4f&gt;</code></pre>
<h3>buf.writeDoubleLE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writedoublele_value_offset_noassert" id="all_buf_writedoublele_value_offset_noassert">#</a></span></h3>
<h3>buf.writeDoubleBE(value, offset, [noAssert])<span><a class="mark" href="#all_buf_writedoublebe_value_offset_noassert" id="all_buf_writedoublebe_value_offset_noassert">#</a></span></h3>
<ul>
<li><code>value</code> Number</li>
<li><code>offset</code> Number</li>
<li><code>noAssert</code> Boolean, Optional, Default: false</li>
</ul>
<p>Writes <code>value</code> to the buffer at the specified offset with specified endian
format. Note, <code>value</code> must be a valid 64 bit double.
</p>
<p>Set <code>noAssert</code> to true to skip validation of <code>value</code> and <code>offset</code>. This means
that <code>value</code> may be too large for the specific function and <code>offset</code> may be
beyond the end of the buffer leading to the values being silently dropped. This
should not be used unless you are certain of correctness. Defaults to <code>false</code>.
</p>
<p>Example:
</p>
<pre><code>var buf = new Buffer(8);
buf.writeDoubleBE(0xdeadbeefcafebabe, 0);
console.log(buf);
buf.writeDoubleLE(0xdeadbeefcafebabe, 0);
console.log(buf);
// &lt;Buffer 43 eb d5 b7 dd f9 5f d7&gt;
// &lt;Buffer d7 5f f9 dd b7 d5 eb 43&gt;</code></pre>
<h3>buf.fill(value, [offset], [end])<span><a class="mark" href="#all_buf_fill_value_offset_end" id="all_buf_fill_value_offset_end">#</a></span></h3>
<div class="signature"><ul>
<li><code>value</code></li>
<li><code>offset</code> Number, Optional</li>
<li><code>end</code> Number, Optional</li>
</div></ul>
<p>Fills the buffer with the specified value. If the <code>offset</code> (defaults to <code>0</code>)
and <code>end</code> (defaults to <code>buffer.length</code>) are not given it will fill the entire
buffer.
</p>
<pre><code>var b = new Buffer(50);
b.fill(&quot;h&quot;);</code></pre>
<h2>buffer.INSPECT_MAX_BYTES<span><a class="mark" href="#all_buffer_inspect_max_bytes" id="all_buffer_inspect_max_bytes">#</a></span></h2>
<div class="signature"><ul>
<li>Number, Default: 50</li>
</div></ul>
<p>How many bytes will be returned when <code>buffer.inspect()</code> is called. This can
be overridden by user modules.
</p>
<p>Note that this is a property on the buffer module returned by
<code>require(&#39;buffer&#39;)</code>, not on the Buffer global, or a buffer instance.
</p>
<h2>Class: SlowBuffer<span><a class="mark" href="#all_class_slowbuffer" id="all_class_slowbuffer">#</a></span></h2>
<p>This class is primarily for internal use. JavaScript programs should
use Buffer instead of using SlowBuffer.
</p>
<p>In order to avoid the overhead of allocating many C++ Buffer objects for
small blocks of memory in the lifetime of a server, Node allocates memory
in 8Kb (8192 byte) chunks. If a buffer is smaller than this size, then it
will be backed by a parent SlowBuffer object. If it is larger than this,
then Node will allocate a SlowBuffer slab for it directly.
</p>
<h1>Stream<span><a class="mark" href="#all_stream" id="all_stream">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable</pre><p>A stream is an abstract interface implemented by various objects in
Node. For example a <a href="http.html#http_http_incomingmessage">request to an HTTP
server</a> is a stream, as is
<a href="process.html#process_process_stdout">stdout</a>. Streams are readable, writable, or both. All streams are
instances of <a href="events.html#events_class_events_eventemitter">EventEmitter</a>
</p>
<p>You can load the Stream base classes by doing <code>require(&#39;stream&#39;)</code>.
There are base classes provided for <a href="#stream_class_stream_readable">Readable</a> streams, <a href="#stream_class_stream_writable">Writable</a>
streams, <a href="#stream_class_stream_duplex">Duplex</a> streams, and <a href="#stream_class_stream_transform">Transform</a> streams.
</p>
<p>This document is split up into 3 sections. The first explains the
parts of the API that you need to be aware of to use streams in your
programs. If you never implement a streaming API yourself, you can
stop there.
</p>
<p>The second section explains the parts of the API that you need to use
if you implement your own custom streams yourself. The API is
designed to make this easy for you to do.
</p>
<p>The third section goes into more depth about how streams work,
including some of the internal mechanisms and functions that you
should probably not modify unless you definitely know what you are
doing.
</p>
<h2>API for Stream Consumers<span><a class="mark" href="#all_api_for_stream_consumers" id="all_api_for_stream_consumers">#</a></span></h2>
<!--type=misc-->
<p>Streams can be either <a href="#stream_class_stream_readable">Readable</a>, <a href="#stream_class_stream_writable">Writable</a>, or both (<a href="#stream_class_stream_duplex">Duplex</a>).
</p>
<p>All streams are EventEmitters, but they also have other custom methods
and properties depending on whether they are Readable, Writable, or
Duplex.
</p>
<p>If a stream is both Readable and Writable, then it implements all of
the methods and events below. So, a <a href="#stream_class_stream_duplex">Duplex</a> or <a href="#stream_class_stream_transform">Transform</a> stream is
fully described by this API, though their implementation may be
somewhat different.
</p>
<p>It is not necessary to implement Stream interfaces in order to consume
streams in your programs. If you <strong>are</strong> implementing streaming
interfaces in your own program, please also refer to
<a href="#stream_api_for_stream_implementors">API for Stream Implementors</a> below.
</p>
<p>Almost all Node programs, no matter how simple, use Streams in some
way. Here is an example of using Streams in a Node program:
</p>
<pre><code class="javascript">var http = require(&#39;http&#39;);
var server = http.createServer(function (req, res) {
// req is an http.IncomingMessage, which is a Readable Stream
// res is an http.ServerResponse, which is a Writable Stream
var body = &#39;&#39;;
// we want to get the data as utf8 strings
// If you don&#39;t set an encoding, then you&#39;ll get Buffer objects
req.setEncoding(&#39;utf8&#39;);
// Readable streams emit &#39;data&#39; events once a listener is added
req.on(&#39;data&#39;, function (chunk) {
body += chunk;
})
// the end event tells you that you have entire body
req.on(&#39;end&#39;, function () {
try {
var data = JSON.parse(body);
} catch (er) {
// uh oh! bad json!
res.statusCode = 400;
return res.end(&#39;error: &#39; + er.message);
}
// write back something interesting to the user:
res.write(typeof data);
res.end();
})
})
server.listen(1337);
// $ curl localhost:1337 -d &#39;{}&#39;
// object
// $ curl localhost:1337 -d &#39;&quot;foo&quot;&#39;
// string
// $ curl localhost:1337 -d &#39;not json&#39;
// error: Unexpected token o</code></pre>
<h3>Class: stream.Readable<span><a class="mark" href="#all_class_stream_readable" id="all_class_stream_readable">#</a></span></h3>
<!--type=class-->
<p>The Readable stream interface is the abstraction for a <em>source</em> of
data that you are reading from. In other words, data comes <em>out</em> of a
Readable stream.
</p>
<p>A Readable stream will not start emitting data until you indicate that
you are ready to receive it.
</p>
<p>Readable streams have two &quot;modes&quot;: a <strong>flowing mode</strong> and a <strong>non-flowing
mode</strong>. When in flowing mode, data is read from the underlying system
and provided to your program as fast as possible. In non-flowing
mode, you must explicitly call <code>stream.read()</code> to get chunks of data
out.
</p>
<p>Examples of readable streams include:
</p>
<ul>
<li><a href="http.html#http_http_incomingmessage">http responses, on the client</a></li>
<li><a href="http.html#http_http_incomingmessage">http requests, on the server</a></li>
<li><a href="fs.html#fs_class_fs_readstream">fs read streams</a></li>
<li><a href="zlib.html">zlib streams</a></li>
<li><a href="crypto.html">crypto streams</a></li>
<li><a href="net.html#net_class_net_socket">tcp sockets</a></li>
<li><a href="child_process.html#child_process_child_stdout">child process stdout and stderr</a></li>
<li><a href="process.html#process_process_stdin">process.stdin</a></li>
</ul>
<h4>Event: &#39;readable&#39;<span><a class="mark" href="#all_event_readable" id="all_event_readable">#</a></span></h4>
<p>When a chunk of data can be read from the stream, it will emit a
<code>&#39;readable&#39;</code> event.
</p>
<p>In some cases, listening for a <code>&#39;readable&#39;</code> event will cause some data
to be read into the internal buffer from the underlying system, if it
hadn&#39;t already.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.on(&#39;readable&#39;, function() {
// there is some data to read now
})</code></pre>
<p>Once the internal buffer is drained, a <code>readable</code> event will fire
again when more data is available.
</p>
<h4>Event: &#39;data&#39;<span><a class="mark" href="#all_event_data" id="all_event_data">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">Buffer | String</span> The chunk of data.</li>
</div></ul>
<p>If you attach a <code>data</code> event listener, then it will switch the stream
into flowing mode, and data will be passed to your handler as soon as
it is available.
</p>
<p>If you just want to get all the data out of the stream as fast as
possible, this is the best way to do so.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.on(&#39;data&#39;, function(chunk) {
console.log(&#39;got %d bytes of data&#39;, chunk.length);
})</code></pre>
<h4>Event: &#39;end&#39;<span><a class="mark" href="#all_event_end" id="all_event_end">#</a></span></h4>
<p>This event fires when no more data will be provided.
</p>
<p>Note that the <code>end</code> event <strong>will not fire</strong> unless the data is
completely consumed. This can be done by switching into flowing mode,
or by calling <code>read()</code> repeatedly until you get to the end.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.on(&#39;data&#39;, function(chunk) {
console.log(&#39;got %d bytes of data&#39;, chunk.length);
})
readable.on(&#39;end&#39;, function() {
console.log(&#39;there will be no more data.&#39;);
});</code></pre>
<h4>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close" id="all_event_close">#</a></span></h4>
<p>Emitted when the underlying resource (for example, the backing file
descriptor) has been closed. Not all streams will emit this.
</p>
<h4>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error" id="all_event_error">#</a></span></h4>
<p>Emitted if there was an error receiving data.
</p>
<h4>readable.read([size])<span><a class="mark" href="#all_readable_read_size" id="all_readable_read_size">#</a></span></h4>
<div class="signature"><ul>
<li><code>size</code> <span class="type">Number</span> Optional argument to specify how much data to read.</li>
<li>Return <span class="type">String | Buffer | null</span></li>
</div></ul>
<p>The <code>read()</code> method pulls some data out of the internal buffer and
returns it. If there is no data available, then it will return
<code>null</code>.
</p>
<p>If you pass in a <code>size</code> argument, then it will return that many
bytes. If <code>size</code> bytes are not available, then it will return <code>null</code>.
</p>
<p>If you do not specify a <code>size</code> argument, then it will return all the
data in the internal buffer.
</p>
<p>This method should only be called in non-flowing mode. In
flowing-mode, this method is called automatically until the internal
buffer is drained.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.on(&#39;readable&#39;, function() {
var chunk;
while (null !== (chunk = readable.read())) {
console.log(&#39;got %d bytes of data&#39;, chunk.length);
}
});</code></pre>
<h4>readable.setEncoding(encoding)<span><a class="mark" href="#all_readable_setencoding_encoding" id="all_readable_setencoding_encoding">#</a></span></h4>
<div class="signature"><ul>
<li><code>encoding</code> <span class="type">String</span> The encoding to use.</li>
</div></ul>
<p>Call this function to cause the stream to return strings of the
specified encoding instead of Buffer objects. For example, if you do
<code>readable.setEncoding(&#39;utf8&#39;)</code>, then the output data will be
interpreted as UTF-8 data, and returned as strings. If you do
<code>readable.setEncoding(&#39;hex&#39;)</code>, then the data will be encoded in
hexadecimal string format.
</p>
<p>This properly handles multi-byte characters that would otherwise be
potentially mangled if you simply pulled the Buffers directly and
called <code>buf.toString(encoding)</code> on them. If you want to read the data
as strings, always use this method.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.setEncoding(&#39;utf8&#39;);
readable.on(&#39;data&#39;, function(chunk) {
assert.equal(typeof chunk, &#39;string&#39;);
console.log(&#39;got %d characters of string data&#39;, chunk.length);
})</code></pre>
<h4>readable.resume()<span><a class="mark" href="#all_readable_resume" id="all_readable_resume">#</a></span></h4>
<p>This method will cause the readable stream to resume emitting <code>data</code>
events.
</p>
<p>This method will switch the stream into flowing-mode. If you do <em>not</em>
want to consume the data from a stream, but you <em>do</em> want to get to
its <code>end</code> event, you can call <code>readable.resume()</code> to open the flow of
data.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.resume();
readable.on(&#39;end&#39;, function(chunk) {
console.log(&#39;got to the end, but did not read anything&#39;);
})</code></pre>
<h4>readable.pause()<span><a class="mark" href="#all_readable_pause" id="all_readable_pause">#</a></span></h4>
<p>This method will cause a stream in flowing-mode to stop emitting
<code>data</code> events. Any data that becomes available will remain in the
internal buffer.
</p>
<p>This method is only relevant in flowing mode. When called on a
non-flowing stream, it will switch into flowing mode, but remain
paused.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
readable.on(&#39;data&#39;, function(chunk) {
console.log(&#39;got %d bytes of data&#39;, chunk.length);
readable.pause();
console.log(&#39;there will be no more data for 1 second&#39;);
setTimeout(function() {
console.log(&#39;now data will start flowing again&#39;);
readable.resume();
}, 1000);
})</code></pre>
<h4>readable.pipe(destination, [options])<span><a class="mark" href="#all_readable_pipe_destination_options" id="all_readable_pipe_destination_options">#</a></span></h4>
<div class="signature"><ul>
<li><code>destination</code> <span class="type"><a href="#stream_class_stream_writable">Writable</a> Stream</span> The destination for writing data</li>
<li><code>options</code> <span class="type">Object</span> Pipe options<ul>
<li><code>end</code> <span class="type">Boolean</span> End the writer when the reader ends. Default = <code>true</code></li>
</ul>
</li>
</div></ul>
<p>This method pulls all the data out of a readable stream, and writes it
to the supplied destination, automatically managing the flow so that
the destination is not overwhelmed by a fast readable stream.
</p>
<p>Multiple destinations can be piped to safely.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
var writable = fs.createWriteStream(&#39;file.txt&#39;);
// All the data from readable goes into &#39;file.txt&#39;
readable.pipe(writable);</code></pre>
<p>This function returns the destination stream, so you can set up pipe
chains like so:
</p>
<pre><code class="javascript">var r = fs.createReadStream(&#39;file.txt&#39;);
var z = zlib.createGzip();
var w = fs.createWriteStream(&#39;file.txt.gz&#39;);
r.pipe(z).pipe(w);</code></pre>
<p>For example, emulating the Unix <code>cat</code> command:
</p>
<pre><code class="javascript">process.stdin.pipe(process.stdout);</code></pre>
<p>By default <a href="#stream_writable_end_chunk_encoding_callback"><code>end()</code></a> is called on the destination when the source stream
emits <code>end</code>, so that <code>destination</code> is no longer writable. Pass <code>{ end:
false }</code> as <code>options</code> to keep the destination stream open.
</p>
<p>This keeps <code>writer</code> open so that &quot;Goodbye&quot; can be written at the
end.
</p>
<pre><code class="javascript">reader.pipe(writer, { end: false });
reader.on(&#39;end&#39;, function() {
writer.end(&#39;Goodbye\n&#39;);
});</code></pre>
<p>Note that <code>process.stderr</code> and <code>process.stdout</code> are never closed until
the process exits, regardless of the specified options.
</p>
<h4>readable.unpipe([destination])<span><a class="mark" href="#all_readable_unpipe_destination" id="all_readable_unpipe_destination">#</a></span></h4>
<div class="signature"><ul>
<li><code>destination</code> <span class="type"><a href="#stream_class_stream_writable">Writable</a> Stream</span> Optional specific stream to unpipe</li>
</div></ul>
<p>This method will remove the hooks set up for a previous <code>pipe()</code> call.
</p>
<p>If the destination is not specified, then all pipes are removed.
</p>
<p>If the destination is specified, but no pipe is set up for it, then
this is a no-op.
</p>
<pre><code class="javascript">var readable = getReadableStreamSomehow();
var writable = fs.createWriteStream(&#39;file.txt&#39;);
// All the data from readable goes into &#39;file.txt&#39;,
// but only for the first second
readable.pipe(writable);
setTimeout(function() {
console.log(&#39;stop writing to file.txt&#39;);
readable.unpipe(writable);
console.log(&#39;manually close the file stream&#39;);
writable.end();
}, 1000);</code></pre>
<h4>readable.unshift(chunk)<span><a class="mark" href="#all_readable_unshift_chunk" id="all_readable_unshift_chunk">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">Buffer | String</span> Chunk of data to unshift onto the read queue</li>
</div></ul>
<p>This is useful in certain cases where a stream is being consumed by a
parser, which needs to &quot;un-consume&quot; some data that it has
optimistically pulled out of the source, so that the stream can be
passed on to some other party.
</p>
<p>If you find that you must often call <code>stream.unshift(chunk)</code> in your
programs, consider implementing a <a href="#stream_class_stream_transform">Transform</a> stream instead. (See API
for Stream Implementors, below.)
</p>
<pre><code class="javascript">// Pull off a header delimited by \n\n
// use unshift() if we get too much
// Call the callback with (error, header, stream)
var StringDecoder = require(&#39;string_decoder&#39;).StringDecoder;
function parseHeader(stream, callback) {
stream.on(&#39;error&#39;, callback);
stream.on(&#39;readable&#39;, onReadable);
var decoder = new StringDecoder(&#39;utf8&#39;);
var header = &#39;&#39;;
function onReadable() {
var chunk;
while (null !== (chunk = stream.read())) {
var str = decoder.write(chunk);
if (str.match(/\n\n/)) {
// found the header boundary
var split = str.split(/\n\n/);
header += split.shift();
var remaining = split.join(&#39;\n\n&#39;);
var buf = new Buffer(remaining, &#39;utf8&#39;);
if (buf.length)
stream.unshift(buf);
stream.removeListener(&#39;error&#39;, callback);
stream.removeListener(&#39;readable&#39;, onReadable);
// now the body of the message can be read from the stream.
callback(null, header, stream);
} else {
// still reading the header.
header += str;
}
}
}
}</code></pre>
<h4>readable.wrap(stream)<span><a class="mark" href="#all_readable_wrap_stream" id="all_readable_wrap_stream">#</a></span></h4>
<div class="signature"><ul>
<li><code>stream</code> <span class="type">Stream</span> An &quot;old style&quot; readable stream</li>
</div></ul>
<p>Versions of Node prior to v0.10 had streams that did not implement the
entire Streams API as it is today. (See &quot;Compatibility&quot; below for
more information.)
</p>
<p>If you are using an older Node library that emits <code>&#39;data&#39;</code> events and
has a <code>pause()</code> method that is advisory only, then you can use the
<code>wrap()</code> method to create a <a href="#stream_class_stream_readable">Readable</a> stream that uses the old stream
as its data source.
</p>
<p>You will very rarely ever need to call this function, but it exists
as a convenience for interacting with old Node programs and libraries.
</p>
<p>For example:
</p>
<pre><code class="javascript">var OldReader = require(&#39;./old-api-module.js&#39;).OldReader;
var oreader = new OldReader;
var Readable = require(&#39;stream&#39;).Readable;
var myReader = new Readable().wrap(oreader);
myReader.on(&#39;readable&#39;, function() {
myReader.read(); // etc.
});</code></pre>
<h3>Class: stream.Writable<span><a class="mark" href="#all_class_stream_writable" id="all_class_stream_writable">#</a></span></h3>
<!--type=class-->
<p>The Writable stream interface is an abstraction for a <em>destination</em>
that you are writing data <em>to</em>.
</p>
<p>Examples of writable streams include:
</p>
<ul>
<li><a href="http.html#http_class_http_clientrequest">http requests, on the client</a></li>
<li><a href="http.html#http_class_http_serverresponse">http responses, on the server</a></li>
<li><a href="fs.html#fs_class_fs_writestream">fs write streams</a></li>
<li><a href="zlib.html">zlib streams</a></li>
<li><a href="crypto.html">crypto streams</a></li>
<li><a href="net.html#net_class_net_socket">tcp sockets</a></li>
<li><a href="child_process.html#child_process_child_stdin">child process stdin</a></li>
<li><a href="process.html#process_process_stdout">process.stdout</a>, <a href="process.html#process_process_stderr">process.stderr</a></li>
</ul>
<h4>writable.write(chunk, [encoding], [callback])<span><a class="mark" href="#all_writable_write_chunk_encoding_callback" id="all_writable_write_chunk_encoding_callback">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">String | Buffer</span> The data to write</li>
<li><code>encoding</code> <span class="type">String</span> The encoding, if <code>chunk</code> is a String</li>
<li><code>callback</code> <span class="type">Function</span> Callback for when this chunk of data is flushed</li>
<li>Returns: <span class="type">Boolean</span> True if the data was handled completely.</li>
</div></ul>
<p>This method writes some data to the underlying system, and calls the
supplied callback once the data has been fully handled.
</p>
<p>The return value indicates if you should continue writing right now.
If the data had to be buffered internally, then it will return
<code>false</code>. Otherwise, it will return <code>true</code>.
</p>
<p>This return value is strictly advisory. You MAY continue to write,
even if it returns <code>false</code>. However, writes will be buffered in
memory, so it is best not to do this excessively. Instead, wait for
the <code>drain</code> event before writing more data.
</p>
<h4>Event: &#39;drain&#39;<span><a class="mark" href="#all_event_drain" id="all_event_drain">#</a></span></h4>
<p>If a <a href="#stream_writable_write_chunk_encoding_callback"><code>writable.write(chunk)</code></a> call returns false, then the <code>drain</code>
event will indicate when it is appropriate to begin writing more data
to the stream.
</p>
<pre><code class="javascript">// Write the data to the supplied writable stream 1MM times.
// Be attentive to back-pressure.
function writeOneMillionTimes(writer, data, encoding, callback) {
var i = 1000000;
write();
function write() {
var ok = true;
do {
i -= 1;
if (i === 0) {
// last time!
writer.write(data, encoding, callback);
} else {
// see if we should continue, or wait
// don&#39;t pass the callback, because we&#39;re not done yet.
ok = writer.write(data, encoding);
}
} while (i &gt; 0 &amp;&amp; ok);
if (i &gt; 0) {
// had to stop early!
// write some more once it drains
writer.once(&#39;drain&#39;, write);
}
}
}</code></pre>
<h4>writable.end([chunk], [encoding], [callback])<span><a class="mark" href="#all_writable_end_chunk_encoding_callback" id="all_writable_end_chunk_encoding_callback">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">String | Buffer</span> Optional data to write</li>
<li><code>encoding</code> <span class="type">String</span> The encoding, if <code>chunk</code> is a String</li>
<li><code>callback</code> <span class="type">Function</span> Optional callback for when the stream is finished</li>
</div></ul>
<p>Call this method when no more data will be written to the stream. If
supplied, the callback is attached as a listener on the <code>finish</code> event.
</p>
<p>Calling <a href="#stream_writable_write_chunk_encoding_callback"><code>write()</code></a> after calling <a href="#stream_writable_end_chunk_encoding_callback"><code>end()</code></a> will raise an error.
</p>
<pre><code class="javascript">// write &#39;hello, &#39; and then end with &#39;world!&#39;
http.createServer(function (req, res) {
res.write(&#39;hello, &#39;);
res.end(&#39;world!&#39;);
// writing more now is not allowed!
});</code></pre>
<h4>Event: &#39;finish&#39;<span><a class="mark" href="#all_event_finish" id="all_event_finish">#</a></span></h4>
<p>When the <a href="#stream_writable_end_chunk_encoding_callback"><code>end()</code></a> method has been called, and all data has been flushed
to the underlying system, this event is emitted.
</p>
<pre><code class="javascript">var writer = getWritableStreamSomehow();
for (var i = 0; i &lt; 100; i ++) {
writer.write(&#39;hello, #&#39; + i + &#39;!\n&#39;);
}
writer.end(&#39;this is the end\n&#39;);
writer.on(&#39;finish&#39;, function() {
console.error(&#39;all writes are now complete.&#39;);
});</code></pre>
<h4>Event: &#39;pipe&#39;<span><a class="mark" href="#all_event_pipe" id="all_event_pipe">#</a></span></h4>
<div class="signature"><ul>
<li><code>src</code> <span class="type"><a href="#stream_class_stream_readable">Readable</a> Stream</span> source stream that is piping to this writable</li>
</div></ul>
<p>This is emitted whenever the <code>pipe()</code> method is called on a readable
stream, adding this writable to its set of destinations.
</p>
<pre><code class="javascript">var writer = getWritableStreamSomehow();
var reader = getReadableStreamSomehow();
writer.on(&#39;pipe&#39;, function(src) {
console.error(&#39;something is piping into the writer&#39;);
assert.equal(src, reader);
});
reader.pipe(writer);</code></pre>
<h4>Event: &#39;unpipe&#39;<span><a class="mark" href="#all_event_unpipe" id="all_event_unpipe">#</a></span></h4>
<div class="signature"><ul>
<li><code>src</code> <span class="type"><a href="#stream_class_stream_readable">Readable</a> Stream</span> The source stream that <a href="#stream_readable_unpipe_destination">unpiped</a> this writable</li>
</div></ul>
<p>This is emitted whenever the <a href="#stream_readable_unpipe_destination"><code>unpipe()</code></a> method is called on a
readable stream, removing this writable from its set of destinations.
</p>
<pre><code class="javascript">var writer = getWritableStreamSomehow();
var reader = getReadableStreamSomehow();
writer.on(&#39;unpipe&#39;, function(src) {
console.error(&#39;something has stopped piping into the writer&#39;);
assert.equal(src, reader);
});
reader.pipe(writer);
reader.unpipe(writer);</code></pre>
<h4>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_1" id="all_event_error_1">#</a></span></h4>
<p>Emitted if there was an error when writing or piping data.
</p>
<h3>Class: stream.Duplex<span><a class="mark" href="#all_class_stream_duplex" id="all_class_stream_duplex">#</a></span></h3>
<p>Duplex streams are streams that implement both the <a href="#stream_class_stream_readable">Readable</a> and
<a href="#stream_class_stream_writable">Writable</a> interfaces. See above for usage.
</p>
<p>Examples of Duplex streams include:
</p>
<ul>
<li><a href="net.html#net_class_net_socket">tcp sockets</a></li>
<li><a href="zlib.html">zlib streams</a></li>
<li><a href="crypto.html">crypto streams</a></li>
</ul>
<h3>Class: stream.Transform<span><a class="mark" href="#all_class_stream_transform" id="all_class_stream_transform">#</a></span></h3>
<p>Transform streams are <a href="#stream_class_stream_duplex">Duplex</a> streams where the output is in some way
computed from the input. They implement both the <a href="#stream_class_stream_readable">Readable</a> and
<a href="#stream_class_stream_writable">Writable</a> interfaces. See above for usage.
</p>
<p>Examples of Transform streams include:
</p>
<ul>
<li><a href="zlib.html">zlib streams</a></li>
<li><a href="crypto.html">crypto streams</a></li>
</ul>
<h2>API for Stream Implementors<span><a class="mark" href="#all_api_for_stream_implementors" id="all_api_for_stream_implementors">#</a></span></h2>
<!--type=misc-->
<p>To implement any sort of stream, the pattern is the same:
</p>
<ol>
<li>Extend the appropriate parent class in your own subclass. (The
<a href="util.html#util_util_inherits_constructor_superconstructor"><code>util.inherits</code></a> method is particularly helpful for this.)</li>
<li>Call the appropriate parent class constructor in your constructor,
to be sure that the internal mechanisms are set up properly.</li>
<li>Implement one or more specific methods, as detailed below.</li>
</ol>
<p>The class to extend and the method(s) to implement depend on the sort
of stream class you are writing:
</p>
<table>
<thead>
<tr>
<th>
<p>Use-case</p>
</th>
<th>
<p>Class</p>
</th>
<th>
<p>Method(s) to implement</p>
</th>
</tr>
</thead>
<tr>
<td>
<p>Reading only</p>
</td>
<td>
<p><a href="#stream_class_stream_readable_1">Readable</a></p>
</td>
<td>
<p><code><a href="#stream_readable_read_size_1">_read</a></code></p>
</td>
</tr>
<tr>
<td>
<p>Writing only</p>
</td>
<td>
<p><a href="#stream_class_stream_writable_1">Writable</a></p>
</td>
<td>
<p><code><a href="#stream_writable_write_chunk_encoding_callback_1">_write</a></code></p>
</td>
</tr>
<tr>
<td>
<p>Reading and writing</p>
</td>
<td>
<p><a href="#stream_class_stream_duplex_1">Duplex</a></p>
</td>
<td>
<p><code><a href="#stream_readable_read_size_1">_read</a></code>, <code><a href="#stream_writable_write_chunk_encoding_callback_1">_write</a></code></p>
</td>
</tr>
<tr>
<td>
<p>Operate on written data, then read the result</p>
</td>
<td>
<p><a href="#stream_class_stream_transform_1">Transform</a></p>
</td>
<td>
<p><code>_transform</code>, <code>_flush</code></p>
</td>
</tr>
</table>
<p>In your implementation code, it is very important to never call the
methods described in <a href="#stream_api_for_stream_consumers">API for Stream Consumers</a> above. Otherwise, you
can potentially cause adverse side effects in programs that consume
your streaming interfaces.
</p>
<h3>Class: stream.Readable<span><a class="mark" href="#all_class_stream_readable_1" id="all_class_stream_readable_1">#</a></span></h3>
<!--type=class-->
<p><code>stream.Readable</code> is an abstract class designed to be extended with an
underlying implementation of the <a href="#stream_readable_read_size_1"><code>_read(size)</code></a> method.
</p>
<p>Please see above under <a href="#stream_api_for_stream_consumers">API for Stream Consumers</a> for how to consume
streams in your programs. What follows is an explanation of how to
implement Readable streams in your programs.
</p>
<h4>Example: A Counting Stream<span><a class="mark" href="#all_example_a_counting_stream" id="all_example_a_counting_stream">#</a></span></h4>
<!--type=example-->
<p>This is a basic example of a Readable stream. It emits the numerals
from 1 to 1,000,000 in ascending order, and then ends.
</p>
<pre><code class="javascript">var Readable = require(&#39;stream&#39;).Readable;
var util = require(&#39;util&#39;);
util.inherits(Counter, Readable);
function Counter(opt) {
Readable.call(this, opt);
this._max = 1000000;
this._index = 1;
}
Counter.prototype._read = function() {
var i = this._index++;
if (i &gt; this._max)
this.push(null);
else {
var str = &#39;&#39; + i;
var buf = new Buffer(str, &#39;ascii&#39;);
this.push(buf);
}
};</code></pre>
<h4>Example: SimpleProtocol v1 (Sub-optimal)<span><a class="mark" href="#all_example_simpleprotocol_v1_sub_optimal" id="all_example_simpleprotocol_v1_sub_optimal">#</a></span></h4>
<p>This is similar to the <code>parseHeader</code> function described above, but
implemented as a custom stream. Also, note that this implementation
does not convert the incoming data to a string.
</p>
<p>However, this would be better implemented as a <a href="#stream_class_stream_transform">Transform</a> stream. See
below for a better implementation.
</p>
<pre><code class="javascript">// A parser for a simple data protocol.
// The &quot;header&quot; is a JSON object, followed by 2 \n characters, and
// then a message body.
//
// NOTE: This can be done more simply as a Transform stream!
// Using Readable directly for this is sub-optimal. See the
// alternative example below under the Transform section.
var Readable = require(&#39;stream&#39;).Readable;
var util = require(&#39;util&#39;);
util.inherits(SimpleProtocol, Readable);
function SimpleProtocol(source, options) {
if (!(this instanceof SimpleProtocol))
return new SimpleProtocol(options);
Readable.call(this, options);
this._inBody = false;
this._sawFirstCr = false;
// source is a readable stream, such as a socket or file
this._source = source;
var self = this;
source.on(&#39;end&#39;, function() {
self.push(null);
});
// give it a kick whenever the source is readable
// read(0) will not consume any bytes
source.on(&#39;readable&#39;, function() {
self.read(0);
});
this._rawHeader = [];
this.header = null;
}
SimpleProtocol.prototype._read = function(n) {
if (!this._inBody) {
var chunk = this._source.read();
// if the source doesn&#39;t have data, we don&#39;t have data yet.
if (chunk === null)
return this.push(&#39;&#39;);
// check if the chunk has a \n\n
var split = -1;
for (var i = 0; i &lt; chunk.length; i++) {
if (chunk[i] === 10) { // &#39;\n&#39;
if (this._sawFirstCr) {
split = i;
break;
} else {
this._sawFirstCr = true;
}
} else {
this._sawFirstCr = false;
}
}
if (split === -1) {
// still waiting for the \n\n
// stash the chunk, and try again.
this._rawHeader.push(chunk);
this.push(&#39;&#39;);
} else {
this._inBody = true;
var h = chunk.slice(0, split);
this._rawHeader.push(h);
var header = Buffer.concat(this._rawHeader).toString();
try {
this.header = JSON.parse(header);
} catch (er) {
this.emit(&#39;error&#39;, new Error(&#39;invalid simple protocol data&#39;));
return;
}
// now, because we got some extra data, unshift the rest
// back into the read queue so that our consumer will see it.
var b = chunk.slice(split);
this.unshift(b);
// and let them know that we are done parsing the header.
this.emit(&#39;header&#39;, this.header);
}
} else {
// from there on, just provide the data to our consumer.
// careful not to push(null), since that would indicate EOF.
var chunk = this._source.read();
if (chunk) this.push(chunk);
}
};
// Usage:
// var parser = new SimpleProtocol(source);
// Now parser is a readable stream that will emit &#39;header&#39;
// with the parsed header data.</code></pre>
<h4>new stream.Readable([options])<span><a class="mark" href="#all_new_stream_readable_options" id="all_new_stream_readable_options">#</a></span></h4>
<div class="signature"><ul>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>highWaterMark</code> <span class="type">Number</span> The maximum number of bytes to store in
the internal buffer before ceasing to read from the underlying
resource. Default=16kb</li>
<li><code>encoding</code> <span class="type">String</span> If specified, then buffers will be decoded to
strings using the specified encoding. Default=null</li>
<li><code>objectMode</code> <span class="type">Boolean</span> Whether this stream should behave
as a stream of objects. Meaning that stream.read(n) returns
a single value instead of a Buffer of size n. Default=false</li>
</ul>
</li>
</div></ul>
<p>In classes that extend the Readable class, make sure to call the
Readable constructor so that the buffering settings can be properly
initialized.
</p>
<h4>readable._read(size)<span><a class="mark" href="#all_readable_read_size_1" id="all_readable_read_size_1">#</a></span></h4>
<div class="signature"><ul>
<li><code>size</code> <span class="type">Number</span> Number of bytes to read asynchronously</li>
</div></ul>
<p>Note: <strong>Implement this function, but do NOT call it directly.</strong>
</p>
<p>This function should NOT be called directly. It should be implemented
by child classes, and only called by the internal Readable class
methods.
</p>
<p>All Readable stream implementations must provide a <code>_read</code> method to
fetch data from the underlying resource.
</p>
<p>This method is prefixed with an underscore because it is internal to
the class that defines it, and should not be called directly by user
programs. However, you <strong>are</strong> expected to override this method in
your own extension classes.
</p>
<p>When data is available, put it into the read queue by calling
<code>readable.push(chunk)</code>. If <code>push</code> returns false, then you should stop
reading. When <code>_read</code> is called again, you should start pushing more
data.
</p>
<p>The <code>size</code> argument is advisory. Implementations where a &quot;read&quot; is a
single call that returns data can use this to know how much data to
fetch. Implementations where that is not relevant, such as TCP or
TLS, may ignore this argument, and simply provide data whenever it
becomes available. There is no need, for example to &quot;wait&quot; until
<code>size</code> bytes are available before calling <a href="#stream_readable_push_chunk_encoding"><code>stream.push(chunk)</code></a>.
</p>
<h4>readable.push(chunk, [encoding])<span><a class="mark" href="#all_readable_push_chunk_encoding" id="all_readable_push_chunk_encoding">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">Buffer | null | String</span> Chunk of data to push into the read queue</li>
<li><code>encoding</code> <span class="type">String</span> Encoding of String chunks. Must be a valid
Buffer encoding, such as <code>&#39;utf8&#39;</code> or <code>&#39;ascii&#39;</code></li>
<li>return <span class="type">Boolean</span> Whether or not more pushes should be performed</li>
</div></ul>
<p>Note: <strong>This function should be called by Readable implementors, NOT
by consumers of Readable streams.</strong>
</p>
<p>The <code>_read()</code> function will not be called again until at least one
<code>push(chunk)</code> call is made.
</p>
<p>The <code>Readable</code> class works by putting data into a read queue to be
pulled out later by calling the <code>read()</code> method when the <code>&#39;readable&#39;</code>
event fires.
</p>
<p>The <code>push()</code> method will explicitly insert some data into the read
queue. If it is called with <code>null</code> then it will signal the end of the
data (EOF).
</p>
<p>This API is designed to be as flexible as possible. For example,
you may be wrapping a lower-level source which has some sort of
pause/resume mechanism, and a data callback. In those cases, you
could wrap the low-level source object by doing something like this:
</p>
<pre><code class="javascript">// source is an object with readStop() and readStart() methods,
// and an `ondata` member that gets called when it has data, and
// an `onend` member that gets called when the data is over.
util.inherits(SourceWrapper, Readable);
function SourceWrapper(options) {
Readable.call(this, options);
this._source = getLowlevelSourceObject();
var self = this;
// Every time there&#39;s data, we push it into the internal buffer.
this._source.ondata = function(chunk) {
// if push() returns false, then we need to stop reading from source
if (!self.push(chunk))
self._source.readStop();
};
// When the source ends, we push the EOF-signalling `null` chunk
this._source.onend = function() {
self.push(null);
};
}
// _read will be called when the stream wants to pull more data in
// the advisory size argument is ignored in this case.
SourceWrapper.prototype._read = function(size) {
this._source.readStart();
};</code></pre>
<h3>Class: stream.Writable<span><a class="mark" href="#all_class_stream_writable_1" id="all_class_stream_writable_1">#</a></span></h3>
<!--type=class-->
<p><code>stream.Writable</code> is an abstract class designed to be extended with an
underlying implementation of the <a href="#stream_writable_write_chunk_encoding_callback_1"><code>_write(chunk, encoding, callback)</code></a> method.
</p>
<p>Please see above under <a href="#stream_api_for_stream_consumers">API for Stream Consumers</a> for how to consume
writable streams in your programs. What follows is an explanation of
how to implement Writable streams in your programs.
</p>
<h4>new stream.Writable([options])<span><a class="mark" href="#all_new_stream_writable_options" id="all_new_stream_writable_options">#</a></span></h4>
<div class="signature"><ul>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>highWaterMark</code> <span class="type">Number</span> Buffer level when <a href="#stream_writable_write_chunk_encoding_callback"><code>write()</code></a> starts
returning false. Default=16kb</li>
<li><code>decodeStrings</code> <span class="type">Boolean</span> Whether or not to decode strings into
Buffers before passing them to <a href="#stream_writable_write_chunk_encoding_callback_1"><code>_write()</code></a>. Default=true</li>
</ul>
</li>
</div></ul>
<p>In classes that extend the Writable class, make sure to call the
constructor so that the buffering settings can be properly
initialized.
</p>
<h4>writable._write(chunk, encoding, callback)<span><a class="mark" href="#all_writable_write_chunk_encoding_callback_1" id="all_writable_write_chunk_encoding_callback_1">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">Buffer | String</span> The chunk to be written. Will always
be a buffer unless the <code>decodeStrings</code> option was set to <code>false</code>.</li>
<li><code>encoding</code> <span class="type">String</span> If the chunk is a string, then this is the
encoding type. Ignore chunk is a buffer. Note that chunk will
<strong>always</strong> be a buffer unless the <code>decodeStrings</code> option is
explicitly set to <code>false</code>.</li>
<li><code>callback</code> <span class="type">Function</span> Call this function (optionally with an error
argument) when you are done processing the supplied chunk.</li>
</div></ul>
<p>All Writable stream implementations must provide a <a href="#stream_writable_write_chunk_encoding_callback_1"><code>_write()</code></a>
method to send data to the underlying resource.
</p>
<p>Note: <strong>This function MUST NOT be called directly.</strong> It should be
implemented by child classes, and called by the internal Writable
class methods only.
</p>
<p>Call the callback using the standard <code>callback(error)</code> pattern to
signal that the write completed successfully or with an error.
</p>
<p>If the <code>decodeStrings</code> flag is set in the constructor options, then
<code>chunk</code> may be a string rather than a Buffer, and <code>encoding</code> will
indicate the sort of string that it is. This is to support
implementations that have an optimized handling for certain string
data encodings. If you do not explicitly set the <code>decodeStrings</code>
option to <code>false</code>, then you can safely ignore the <code>encoding</code> argument,
and assume that <code>chunk</code> will always be a Buffer.
</p>
<p>This method is prefixed with an underscore because it is internal to
the class that defines it, and should not be called directly by user
programs. However, you <strong>are</strong> expected to override this method in
your own extension classes.
</p>
<h3>Class: stream.Duplex<span><a class="mark" href="#all_class_stream_duplex_1" id="all_class_stream_duplex_1">#</a></span></h3>
<!--type=class-->
<p>A &quot;duplex&quot; stream is one that is both Readable and Writable, such as a
TCP socket connection.
</p>
<p>Note that <code>stream.Duplex</code> is an abstract class designed to be extended
with an underlying implementation of the <code>_read(size)</code> and
<a href="#stream_writable_write_chunk_encoding_callback_1"><code>_write(chunk, encoding, callback)</code></a> methods as you would with a
Readable or Writable stream class.
</p>
<p>Since JavaScript doesn&#39;t have multiple prototypal inheritance, this
class prototypally inherits from Readable, and then parasitically from
Writable. It is thus up to the user to implement both the lowlevel
<code>_read(n)</code> method as well as the lowlevel
<a href="#stream_writable_write_chunk_encoding_callback_1"><code>_write(chunk, encoding, callback)</code></a> method on extension duplex classes.
</p>
<h4>new stream.Duplex(options)<span><a class="mark" href="#all_new_stream_duplex_options" id="all_new_stream_duplex_options">#</a></span></h4>
<div class="signature"><ul>
<li><code>options</code> <span class="type">Object</span> Passed to both Writable and Readable
constructors. Also has the following fields:<ul>
<li><code>allowHalfOpen</code> <span class="type">Boolean</span> Default=true. If set to <code>false</code>, then
the stream will automatically end the readable side when the
writable side ends and vice versa.</li>
</ul>
</li>
</div></ul>
<p>In classes that extend the Duplex class, make sure to call the
constructor so that the buffering settings can be properly
initialized.
</p>
<h3>Class: stream.Transform<span><a class="mark" href="#all_class_stream_transform_1" id="all_class_stream_transform_1">#</a></span></h3>
<p>A &quot;transform&quot; stream is a duplex stream where the output is causally
connected in some way to the input, such as a <a href="zlib.html">zlib</a> stream or a
<a href="crypto.html">crypto</a> stream.
</p>
<p>There is no requirement that the output be the same size as the input,
the same number of chunks, or arrive at the same time. For example, a
Hash stream will only ever have a single chunk of output which is
provided when the input is ended. A zlib stream will produce output
that is either much smaller or much larger than its input.
</p>
<p>Rather than implement the <a href="#stream_readable_read_size_1"><code>_read()</code></a> and <a href="#stream_writable_write_chunk_encoding_callback_1"><code>_write()</code></a> methods, Transform
classes must implement the <code>_transform()</code> method, and may optionally
also implement the <code>_flush()</code> method. (See below.)
</p>
<h4>new stream.Transform([options])<span><a class="mark" href="#all_new_stream_transform_options" id="all_new_stream_transform_options">#</a></span></h4>
<div class="signature"><ul>
<li><code>options</code> <span class="type">Object</span> Passed to both Writable and Readable
constructors.</li>
</div></ul>
<p>In classes that extend the Transform class, make sure to call the
constructor so that the buffering settings can be properly
initialized.
</p>
<h4>transform._transform(chunk, encoding, callback)<span><a class="mark" href="#all_transform_transform_chunk_encoding_callback" id="all_transform_transform_chunk_encoding_callback">#</a></span></h4>
<div class="signature"><ul>
<li><code>chunk</code> <span class="type">Buffer | String</span> The chunk to be transformed. Will always
be a buffer unless the <code>decodeStrings</code> option was set to <code>false</code>.</li>
<li><code>encoding</code> <span class="type">String</span> If the chunk is a string, then this is the
encoding type. (Ignore if <code>decodeStrings</code> chunk is a buffer.)</li>
<li><code>callback</code> <span class="type">Function</span> Call this function (optionally with an error
argument) when you are done processing the supplied chunk.</li>
</div></ul>
<p>Note: <strong>This function MUST NOT be called directly.</strong> It should be
implemented by child classes, and called by the internal Transform
class methods only.
</p>
<p>All Transform stream implementations must provide a <code>_transform</code>
method to accept input and produce output.
</p>
<p><code>_transform</code> should do whatever has to be done in this specific
Transform class, to handle the bytes being written, and pass them off
to the readable portion of the interface. Do asynchronous I/O,
process things, and so on.
</p>
<p>Call <code>transform.push(outputChunk)</code> 0 or more times to generate output
from this input chunk, depending on how much data you want to output
as a result of this chunk.
</p>
<p>Call the callback function only when the current chunk is completely
consumed. Note that there may or may not be output as a result of any
particular input chunk.
</p>
<p>This method is prefixed with an underscore because it is internal to
the class that defines it, and should not be called directly by user
programs. However, you <strong>are</strong> expected to override this method in
your own extension classes.
</p>
<h4>transform._flush(callback)<span><a class="mark" href="#all_transform_flush_callback" id="all_transform_flush_callback">#</a></span></h4>
<div class="signature"><ul>
<li><code>callback</code> <span class="type">Function</span> Call this function (optionally with an error
argument) when you are done flushing any remaining data.</li>
</div></ul>
<p>Note: <strong>This function MUST NOT be called directly.</strong> It MAY be implemented
by child classes, and if so, will be called by the internal Transform
class methods only.
</p>
<p>In some cases, your transform operation may need to emit a bit more
data at the end of the stream. For example, a <code>Zlib</code> compression
stream will store up some internal state so that it can optimally
compress the output. At the end, however, it needs to do the best it
can with what is left, so that the data will be complete.
</p>
<p>In those cases, you can implement a <code>_flush</code> method, which will be
called at the very end, after all the written data is consumed, but
before emitting <code>end</code> to signal the end of the readable side. Just
like with <code>_transform</code>, call <code>transform.push(chunk)</code> zero or more
times, as appropriate, and call <code>callback</code> when the flush operation is
complete.
</p>
<p>This method is prefixed with an underscore because it is internal to
the class that defines it, and should not be called directly by user
programs. However, you <strong>are</strong> expected to override this method in
your own extension classes.
</p>
<h4>Example: <code>SimpleProtocol</code> parser v2<span><a class="mark" href="#all_example_simpleprotocol_parser_v2" id="all_example_simpleprotocol_parser_v2">#</a></span></h4>
<p>The example above of a simple protocol parser can be implemented
simply by using the higher level <a href="#stream_class_stream_transform">Transform</a> stream class, similar to
the <code>parseHeader</code> and <code>SimpleProtocol v1</code> examples above.
</p>
<p>In this example, rather than providing the input as an argument, it
would be piped into the parser, which is a more idiomatic Node stream
approach.
</p>
<pre><code class="javascript">var util = require(&#39;util&#39;);
var Transform = require(&#39;stream&#39;).Transform;
util.inherits(SimpleProtocol, Transform);
function SimpleProtocol(options) {
if (!(this instanceof SimpleProtocol))
return new SimpleProtocol(options);
Transform.call(this, options);
this._inBody = false;
this._sawFirstCr = false;
this._rawHeader = [];
this.header = null;
}
SimpleProtocol.prototype._transform = function(chunk, encoding, done) {
if (!this._inBody) {
// check if the chunk has a \n\n
var split = -1;
for (var i = 0; i &lt; chunk.length; i++) {
if (chunk[i] === 10) { // &#39;\n&#39;
if (this._sawFirstCr) {
split = i;
break;
} else {
this._sawFirstCr = true;
}
} else {
this._sawFirstCr = false;
}
}
if (split === -1) {
// still waiting for the \n\n
// stash the chunk, and try again.
this._rawHeader.push(chunk);
} else {
this._inBody = true;
var h = chunk.slice(0, split);
this._rawHeader.push(h);
var header = Buffer.concat(this._rawHeader).toString();
try {
this.header = JSON.parse(header);
} catch (er) {
this.emit(&#39;error&#39;, new Error(&#39;invalid simple protocol data&#39;));
return;
}
// and let them know that we are done parsing the header.
this.emit(&#39;header&#39;, this.header);
// now, because we got some extra data, emit this first.
this.push(chunk.slice(split));
}
} else {
// from there on, just provide the data to our consumer as-is.
this.push(chunk);
}
done();
};
// Usage:
// var parser = new SimpleProtocol();
// source.pipe(parser)
// Now parser is a readable stream that will emit &#39;header&#39;
// with the parsed header data.</code></pre>
<h3>Class: stream.PassThrough<span><a class="mark" href="#all_class_stream_passthrough" id="all_class_stream_passthrough">#</a></span></h3>
<p>This is a trivial implementation of a <a href="#stream_class_stream_transform">Transform</a> stream that simply
passes the input bytes across to the output. Its purpose is mainly
for examples and testing, but there are occasionally use cases where
it can come in handy as a building block for novel sorts of streams.
</p>
<h2>Streams: Under the Hood<span><a class="mark" href="#all_streams_under_the_hood" id="all_streams_under_the_hood">#</a></span></h2>
<!--type=misc-->
<h3>Buffering<span><a class="mark" href="#all_buffering" id="all_buffering">#</a></span></h3>
<!--type=misc-->
<p>Both Writable and Readable streams will buffer data on an internal
object called <code>_writableState.buffer</code> or <code>_readableState.buffer</code>,
respectively.
</p>
<p>The amount of data that will potentially be buffered depends on the
<code>highWaterMark</code> option which is passed into the constructor.
</p>
<p>Buffering in Readable streams happens when the implementation calls
<a href="#stream_readable_push_chunk_encoding"><code>stream.push(chunk)</code></a>. If the consumer of the Stream does not call
<code>stream.read()</code>, then the data will sit in the internal queue until it
is consumed.
</p>
<p>Buffering in Writable streams happens when the user calls
<a href="#stream_writable_write_chunk_encoding_callback"><code>stream.write(chunk)</code></a> repeatedly, even when <code>write()</code> returns <code>false</code>.
</p>
<p>The purpose of streams, especially with the <code>pipe()</code> method, is to
limit the buffering of data to acceptable levels, so that sources and
destinations of varying speed will not overwhelm the available memory.
</p>
<h3><code>stream.read(0)</code><span><a class="mark" href="#all_stream_read_0" id="all_stream_read_0">#</a></span></h3>
<p>There are some cases where you want to trigger a refresh of the
underlying readable stream mechanisms, without actually consuming any
data. In that case, you can call <code>stream.read(0)</code>, which will always
return null.
</p>
<p>If the internal read buffer is below the <code>highWaterMark</code>, and the
stream is not currently reading, then calling <code>read(0)</code> will trigger
a low-level <code>_read</code> call.
</p>
<p>There is almost never a need to do this. However, you will see some
cases in Node&#39;s internals where this is done, particularly in the
Readable stream class internals.
</p>
<h3><code>stream.push(&#39;&#39;)</code><span><a class="mark" href="#all_stream_push" id="all_stream_push">#</a></span></h3>
<p>Pushing a zero-byte string or Buffer (when not in <a href="#stream_object_mode">Object mode</a>) has an
interesting side effect. Because it <em>is</em> a call to
<a href="#stream_readable_push_chunk_encoding"><code>stream.push()</code></a>, it will end the <code>reading</code> process. However, it
does <em>not</em> add any data to the readable buffer, so there&#39;s nothing for
a user to consume.
</p>
<p>Very rarely, there are cases where you have no data to provide now,
but the consumer of your stream (or, perhaps, another bit of your own
code) will know when to check again, by calling <code>stream.read(0)</code>. In
those cases, you <em>may</em> call <code>stream.push(&#39;&#39;)</code>.
</p>
<p>So far, the only use case for this functionality is in the
<a href="tls.html#tls_class_cryptostream">tls.CryptoStream</a> class, which is deprecated in Node v0.12. If you
find that you have to use <code>stream.push(&#39;&#39;)</code>, please consider another
approach, because it almost certainly indicates that something is
horribly wrong.
</p>
<h3>Compatibility with Older Node Versions<span><a class="mark" href="#all_compatibility_with_older_node_versions" id="all_compatibility_with_older_node_versions">#</a></span></h3>
<!--type=misc-->
<p>In versions of Node prior to v0.10, the Readable stream interface was
simpler, but also less powerful and less useful.
</p>
<ul>
<li>Rather than waiting for you to call the <code>read()</code> method, <code>&#39;data&#39;</code>
events would start emitting immediately. If you needed to do some
I/O to decide how to handle data, then you had to store the chunks
in some kind of buffer so that they would not be lost.</li>
<li>The <code>pause()</code> method was advisory, rather than guaranteed. This
meant that you still had to be prepared to receive <code>&#39;data&#39;</code> events
even when the stream was in a paused state.</li>
</ul>
<p>In Node v0.10, the Readable class described below was added. For
backwards compatibility with older Node programs, Readable streams
switch into &quot;flowing mode&quot; when a <code>&#39;data&#39;</code> event handler is added, or
when the <code>pause()</code> or <code>resume()</code> methods are called. The effect is
that, even if you are not using the new <code>read()</code> method and
<code>&#39;readable&#39;</code> event, you no longer have to worry about losing <code>&#39;data&#39;</code>
chunks.
</p>
<p>Most programs will continue to function normally. However, this
introduces an edge case in the following conditions:
</p>
<ul>
<li>No <code>&#39;data&#39;</code> event handler is added.</li>
<li>The <code>pause()</code> and <code>resume()</code> methods are never called.</li>
</ul>
<p>For example, consider the following code:
</p>
<pre><code class="javascript">// WARNING! BROKEN!
net.createServer(function(socket) {
// we add an &#39;end&#39; method, but never consume the data
socket.on(&#39;end&#39;, function() {
// It will never get here.
socket.end(&#39;I got your message (but didnt read it)\n&#39;);
});
}).listen(1337);</code></pre>
<p>In versions of node prior to v0.10, the incoming message data would be
simply discarded. However, in Node v0.10 and beyond, the socket will
remain paused forever.
</p>
<p>The workaround in this situation is to call the <code>resume()</code> method to
trigger &quot;old mode&quot; behavior:
</p>
<pre><code class="javascript">// Workaround
net.createServer(function(socket) {
socket.on(&#39;end&#39;, function() {
socket.end(&#39;I got your message (but didnt read it)\n&#39;);
});
// start the flow of data, discarding it.
socket.resume();
}).listen(1337);</code></pre>
<p>In addition to new Readable streams switching into flowing-mode, pre-v0.10
style streams can be wrapped in a Readable class using the <code>wrap()</code>
method.
</p>
<h3>Object Mode<span><a class="mark" href="#all_object_mode" id="all_object_mode">#</a></span></h3>
<!--type=misc-->
<p>Normally, Streams operate on Strings and Buffers exclusively.
</p>
<p>Streams that are in <strong>object mode</strong> can emit generic JavaScript values
other than Buffers and Strings.
</p>
<p>A Readable stream in object mode will always return a single item from
a call to <code>stream.read(size)</code>, regardless of what the size argument
is.
</p>
<p>A Writable stream in object mode will always ignore the <code>encoding</code>
argument to <code>stream.write(data, encoding)</code>.
</p>
<p>The special value <code>null</code> still retains its special value for object
mode streams. That is, for object mode readable streams, <code>null</code> as a
return value from <code>stream.read()</code> indicates that there is no more
data, and <a href="#stream_readable_push_chunk_encoding"><code>stream.push(null)</code></a> will signal the end of stream data
(<code>EOF</code>).
</p>
<p>No streams in Node core are object mode streams. This pattern is only
used by userland streaming libraries.
</p>
<p>You should set <code>objectMode</code> in your stream child class constructor on
the options object. Setting <code>objectMode</code> mid-stream is not safe.
</p>
<h3>State Objects<span><a class="mark" href="#all_state_objects" id="all_state_objects">#</a></span></h3>
<p><a href="#stream_class_stream_readable">Readable</a> streams have a member object called <code>_readableState</code>.
<a href="#stream_class_stream_writable">Writable</a> streams have a member object called <code>_writableState</code>.
<a href="#stream_class_stream_duplex">Duplex</a> streams have both.
</p>
<p><strong>These objects should generally not be modified in child classes.</strong>
However, if you have a Duplex or Transform stream that should be in
<code>objectMode</code> on the readable side, and not in <code>objectMode</code> on the
writable side, then you may do this in the constructor by setting the
flag explicitly on the appropriate state object.
</p>
<pre><code class="javascript">var util = require(&#39;util&#39;);
var StringDecoder = require(&#39;string_decoder&#39;).StringDecoder;
var Transform = require(&#39;stream&#39;).Transform;
util.inherits(JSONParseStream, Transform);
// Gets \n-delimited JSON string data, and emits the parsed objects
function JSONParseStream(options) {
if (!(this instanceof JSONParseStream))
return new JSONParseStream(options);
Transform.call(this, options);
this._writableState.objectMode = false;
this._readableState.objectMode = true;
this._buffer = &#39;&#39;;
this._decoder = new StringDecoder(&#39;utf8&#39;);
}
JSONParseStream.prototype._transform = function(chunk, encoding, cb) {
this._buffer += this._decoder.write(chunk);
// split on newlines
var lines = this._buffer.split(/\r?\n/);
// keep the last partial line buffered
this._buffer = lines.pop();
for (var l = 0; l &lt; lines.length; l++) {
var line = lines[l];
try {
var obj = JSON.parse(line);
} catch (er) {
this.emit(&#39;error&#39;, er);
return;
}
// push the parsed object out to the readable consumer
this.push(obj);
}
cb();
};
JSONParseStream.prototype._flush = function(cb) {
// Just handle any leftover
var rem = this._buffer.trim();
if (rem) {
try {
var obj = JSON.parse(rem);
} catch (er) {
this.emit(&#39;error&#39;, er);
return;
}
// push the parsed object out to the readable consumer
this.push(obj);
}
cb();
};</code></pre>
<p>The state objects contain other useful information for debugging the
state of streams in your programs. It is safe to look at them, but
beyond setting option flags in the constructor, it is <strong>not</strong> safe to
modify them.
</p>
<h1>Crypto<span><a class="mark" href="#all_crypto" id="all_crypto">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable; API changes are being discussed for
future versions. Breaking changes will be minimized. See below.</pre><p>Use <code>require(&#39;crypto&#39;)</code> to access this module.
</p>
<p>The crypto module offers a way of encapsulating secure credentials to be
used as part of a secure HTTPS net or http connection.
</p>
<p>It also offers a set of wrappers for OpenSSL&#39;s hash, hmac, cipher,
decipher, sign and verify methods.
</p>
<h2>crypto.getCiphers()<span><a class="mark" href="#all_crypto_getciphers" id="all_crypto_getciphers">#</a></span></h2>
<p>Returns an array with the names of the supported ciphers.
</p>
<p>Example:
</p>
<pre><code>var ciphers = crypto.getCiphers();
console.log(ciphers); // [&#39;AES-128-CBC&#39;, &#39;AES-128-CBC-HMAC-SHA1&#39;, ...]</code></pre>
<h2>crypto.getHashes()<span><a class="mark" href="#all_crypto_gethashes" id="all_crypto_gethashes">#</a></span></h2>
<p>Returns an array with the names of the supported hash algorithms.
</p>
<p>Example:
</p>
<pre><code>var hashes = crypto.getHashes();
console.log(hashes); // [&#39;sha&#39;, &#39;sha1&#39;, &#39;sha1WithRSAEncryption&#39;, ...]</code></pre>
<h2>crypto.createCredentials(details)<span><a class="mark" href="#all_crypto_createcredentials_details" id="all_crypto_createcredentials_details">#</a></span></h2>
<p>Creates a credentials object, with the optional details being a
dictionary with keys:
</p>
<ul>
<li><code>pfx</code> : A string or buffer holding the PFX or PKCS12 encoded private
key, certificate and CA certificates</li>
<li><code>key</code> : A string holding the PEM encoded private key</li>
<li><code>passphrase</code> : A string of passphrase for the private key or pfx</li>
<li><code>cert</code> : A string holding the PEM encoded certificate</li>
<li><code>ca</code> : Either a string or list of strings of PEM encoded CA
certificates to trust.</li>
<li><code>crl</code> : Either a string or list of strings of PEM encoded CRLs
(Certificate Revocation List)</li>
<li><code>ciphers</code>: A string describing the ciphers to use or exclude.
Consult
<a href="http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT">http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT</a>
for details on the format.</li>
</ul>
<p>If no &#39;ca&#39; details are given, then node.js will use the default
publicly trusted list of CAs as given in
</p>
<p><a href="http://mxr.mozilla.org/mozilla/source/security/nss/lib/ckfw/builtins/certdata.txt">http://mxr.mozilla.org/mozilla/source/security/nss/lib/ckfw/builtins/certdata.txt</a>.
</p>
<h2>crypto.createHash(algorithm)<span><a class="mark" href="#all_crypto_createhash_algorithm" id="all_crypto_createhash_algorithm">#</a></span></h2>
<p>Creates and returns a hash object, a cryptographic hash with the given
algorithm which can be used to generate hash digests.
</p>
<p><code>algorithm</code> is dependent on the available algorithms supported by the
version of OpenSSL on the platform. Examples are <code>&#39;sha1&#39;</code>, <code>&#39;md5&#39;</code>,
<code>&#39;sha256&#39;</code>, <code>&#39;sha512&#39;</code>, etc. On recent releases, <code>openssl
list-message-digest-algorithms</code> will display the available digest
algorithms.
</p>
<p>Example: this program that takes the sha1 sum of a file
</p>
<pre><code>var filename = process.argv[2];
var crypto = require(&#39;crypto&#39;);
var fs = require(&#39;fs&#39;);
var shasum = crypto.createHash(&#39;sha1&#39;);
var s = fs.ReadStream(filename);
s.on(&#39;data&#39;, function(d) {
shasum.update(d);
});
s.on(&#39;end&#39;, function() {
var d = shasum.digest(&#39;hex&#39;);
console.log(d + &#39; &#39; + filename);
});</code></pre>
<h2>Class: Hash<span><a class="mark" href="#all_class_hash" id="all_class_hash">#</a></span></h2>
<p>The class for creating hash digests of data.
</p>
<p>It is a <a href="stream.html">stream</a> that is both readable and writable. The
written data is used to compute the hash. Once the writable side of
the stream is ended, use the <code>read()</code> method to get the computed hash
digest. The legacy <code>update</code> and <code>digest</code> methods are also supported.
</p>
<p>Returned by <code>crypto.createHash</code>.
</p>
<h3>hash.update(data, [input_encoding])<span><a class="mark" href="#all_hash_update_data_input_encoding" id="all_hash_update_data_input_encoding">#</a></span></h3>
<p>Updates the hash content with the given <code>data</code>, the encoding of which
is given in <code>input_encoding</code> and can be <code>&#39;utf8&#39;</code>, <code>&#39;ascii&#39;</code> or
<code>&#39;binary&#39;</code>. If no encoding is provided and the input is a string an
encoding of <code>&#39;binary&#39;</code> is enforced. If <code>data</code> is a <code>Buffer</code> then
<code>input_encoding</code> is ignored.
</p>
<p>This can be called many times with new data as it is streamed.
</p>
<h3>hash.digest([encoding])<span><a class="mark" href="#all_hash_digest_encoding" id="all_hash_digest_encoding">#</a></span></h3>
<p>Calculates the digest of all of the passed data to be hashed. The
<code>encoding</code> can be <code>&#39;hex&#39;</code>, <code>&#39;binary&#39;</code> or <code>&#39;base64&#39;</code>. If no encoding
is provided, then a buffer is returned.
</p>
<p>Note: <code>hash</code> object can not be used after <code>digest()</code> method has been
called.
</p>
<h2>crypto.createHmac(algorithm, key)<span><a class="mark" href="#all_crypto_createhmac_algorithm_key" id="all_crypto_createhmac_algorithm_key">#</a></span></h2>
<p>Creates and returns a hmac object, a cryptographic hmac with the given
algorithm and key.
</p>
<p>It is a <a href="stream.html">stream</a> that is both readable and writable. The
written data is used to compute the hmac. Once the writable side of
the stream is ended, use the <code>read()</code> method to get the computed
digest. The legacy <code>update</code> and <code>digest</code> methods are also supported.
</p>
<p><code>algorithm</code> is dependent on the available algorithms supported by
OpenSSL - see createHash above. <code>key</code> is the hmac key to be used.
</p>
<h2>Class: Hmac<span><a class="mark" href="#all_class_hmac" id="all_class_hmac">#</a></span></h2>
<p>Class for creating cryptographic hmac content.
</p>
<p>Returned by <code>crypto.createHmac</code>.
</p>
<h3>hmac.update(data)<span><a class="mark" href="#all_hmac_update_data" id="all_hmac_update_data">#</a></span></h3>
<p>Update the hmac content with the given <code>data</code>. This can be called
many times with new data as it is streamed.
</p>
<h3>hmac.digest([encoding])<span><a class="mark" href="#all_hmac_digest_encoding" id="all_hmac_digest_encoding">#</a></span></h3>
<p>Calculates the digest of all of the passed data to the hmac. The
<code>encoding</code> can be <code>&#39;hex&#39;</code>, <code>&#39;binary&#39;</code> or <code>&#39;base64&#39;</code>. If no encoding
is provided, then a buffer is returned.
</p>
<p>Note: <code>hmac</code> object can not be used after <code>digest()</code> method has been
called.
</p>
<h2>crypto.createCipher(algorithm, password)<span><a class="mark" href="#all_crypto_createcipher_algorithm_password" id="all_crypto_createcipher_algorithm_password">#</a></span></h2>
<p>Creates and returns a cipher object, with the given algorithm and
password.
</p>
<p><code>algorithm</code> is dependent on OpenSSL, examples are <code>&#39;aes192&#39;</code>, etc. On
recent releases, <code>openssl list-cipher-algorithms</code> will display the
available cipher algorithms. <code>password</code> is used to derive key and IV,
which must be a <code>&#39;binary&#39;</code> encoded string or a <a href="buffer.html">buffer</a>.
</p>
<p>It is a <a href="stream.html">stream</a> that is both readable and writable. The
written data is used to compute the hash. Once the writable side of
the stream is ended, use the <code>read()</code> method to get the computed hash
digest. The legacy <code>update</code> and <code>digest</code> methods are also supported.
</p>
<h2>crypto.createCipheriv(algorithm, key, iv)<span><a class="mark" href="#all_crypto_createcipheriv_algorithm_key_iv" id="all_crypto_createcipheriv_algorithm_key_iv">#</a></span></h2>
<p>Creates and returns a cipher object, with the given algorithm, key and
iv.
</p>
<p><code>algorithm</code> is the same as the argument to <code>createCipher()</code>. <code>key</code> is
the raw key used by the algorithm. <code>iv</code> is an <a href="http://en.wikipedia.org/wiki/Initialization_vector">initialization
vector</a>.
</p>
<p><code>key</code> and <code>iv</code> must be <code>&#39;binary&#39;</code> encoded strings or
<a href="buffer.html">buffers</a>.
</p>
<h2>Class: Cipher<span><a class="mark" href="#all_class_cipher" id="all_class_cipher">#</a></span></h2>
<p>Class for encrypting data.
</p>
<p>Returned by <code>crypto.createCipher</code> and <code>crypto.createCipheriv</code>.
</p>
<p>Cipher objects are <a href="stream.html">streams</a> that are both readable and
writable. The written plain text data is used to produce the
encrypted data on the readable side. The legacy <code>update</code> and <code>final</code>
methods are also supported.
</p>
<h3>cipher.update(data, [input_encoding], [output_encoding])<span><a class="mark" href="#all_cipher_update_data_input_encoding_output_encoding" id="all_cipher_update_data_input_encoding_output_encoding">#</a></span></h3>
<p>Updates the cipher with <code>data</code>, the encoding of which is given in
<code>input_encoding</code> and can be <code>&#39;utf8&#39;</code>, <code>&#39;ascii&#39;</code> or <code>&#39;binary&#39;</code>. If no
encoding is provided, then a buffer is expected.
If <code>data</code> is a <code>Buffer</code> then <code>input_encoding</code> is ignored.
</p>
<p>The <code>output_encoding</code> specifies the output format of the enciphered
data, and can be <code>&#39;binary&#39;</code>, <code>&#39;base64&#39;</code> or <code>&#39;hex&#39;</code>. If no encoding is
provided, then a buffer is returned.
</p>
<p>Returns the enciphered contents, and can be called many times with new
data as it is streamed.
</p>
<h3>cipher.final([output_encoding])<span><a class="mark" href="#all_cipher_final_output_encoding" id="all_cipher_final_output_encoding">#</a></span></h3>
<p>Returns any remaining enciphered contents, with <code>output_encoding</code>
being one of: <code>&#39;binary&#39;</code>, <code>&#39;base64&#39;</code> or <code>&#39;hex&#39;</code>. If no encoding is
provided, then a buffer is returned.
</p>
<p>Note: <code>cipher</code> object can not be used after <code>final()</code> method has been
called.
</p>
<h3>cipher.setAutoPadding(auto_padding=true)<span><a class="mark" href="#all_cipher_setautopadding_auto_padding_true" id="all_cipher_setautopadding_auto_padding_true">#</a></span></h3>
<p>You can disable automatic padding of the input data to block size. If
<code>auto_padding</code> is false, the length of the entire input data must be a
multiple of the cipher&#39;s block size or <code>final</code> will fail. Useful for
non-standard padding, e.g. using <code>0x0</code> instead of PKCS padding. You
must call this before <code>cipher.final</code>.
</p>
<h2>crypto.createDecipher(algorithm, password)<span><a class="mark" href="#all_crypto_createdecipher_algorithm_password" id="all_crypto_createdecipher_algorithm_password">#</a></span></h2>
<p>Creates and returns a decipher object, with the given algorithm and
key. This is the mirror of the <a href="#crypto_crypto_createcipher_algorithm_password">createCipher()</a> above.
</p>
<h2>crypto.createDecipheriv(algorithm, key, iv)<span><a class="mark" href="#all_crypto_createdecipheriv_algorithm_key_iv" id="all_crypto_createdecipheriv_algorithm_key_iv">#</a></span></h2>
<p>Creates and returns a decipher object, with the given algorithm, key
and iv. This is the mirror of the <a href="#crypto_crypto_createcipheriv_algorithm_key_iv">createCipheriv()</a> above.
</p>
<h2>Class: Decipher<span><a class="mark" href="#all_class_decipher" id="all_class_decipher">#</a></span></h2>
<p>Class for decrypting data.
</p>
<p>Returned by <code>crypto.createDecipher</code> and <code>crypto.createDecipheriv</code>.
</p>
<p>Decipher objects are <a href="stream.html">streams</a> that are both readable and
writable. The written enciphered data is used to produce the
plain-text data on the the readable side. The legacy <code>update</code> and
<code>final</code> methods are also supported.
</p>
<h3>decipher.update(data, [input_encoding], [output_encoding])<span><a class="mark" href="#all_decipher_update_data_input_encoding_output_encoding" id="all_decipher_update_data_input_encoding_output_encoding">#</a></span></h3>
<p>Updates the decipher with <code>data</code>, which is encoded in <code>&#39;binary&#39;</code>,
<code>&#39;base64&#39;</code> or <code>&#39;hex&#39;</code>. If no encoding is provided, then a buffer is
expected.
If <code>data</code> is a <code>Buffer</code> then <code>input_encoding</code> is ignored.
</p>
<p>The <code>output_decoding</code> specifies in what format to return the
deciphered plaintext: <code>&#39;binary&#39;</code>, <code>&#39;ascii&#39;</code> or <code>&#39;utf8&#39;</code>. If no
encoding is provided, then a buffer is returned.
</p>
<h3>decipher.final([output_encoding])<span><a class="mark" href="#all_decipher_final_output_encoding" id="all_decipher_final_output_encoding">#</a></span></h3>
<p>Returns any remaining plaintext which is deciphered, with
<code>output_encoding</code> being one of: <code>&#39;binary&#39;</code>, <code>&#39;ascii&#39;</code> or <code>&#39;utf8&#39;</code>. If
no encoding is provided, then a buffer is returned.
</p>
<p>Note: <code>decipher</code> object can not be used after <code>final()</code> method has been
called.
</p>
<h3>decipher.setAutoPadding(auto_padding=true)<span><a class="mark" href="#all_decipher_setautopadding_auto_padding_true" id="all_decipher_setautopadding_auto_padding_true">#</a></span></h3>
<p>You can disable auto padding if the data has been encrypted without
standard block padding to prevent <code>decipher.final</code> from checking and
removing it. Can only work if the input data&#39;s length is a multiple of
the ciphers block size. You must call this before streaming data to
<code>decipher.update</code>.
</p>
<h2>crypto.createSign(algorithm)<span><a class="mark" href="#all_crypto_createsign_algorithm" id="all_crypto_createsign_algorithm">#</a></span></h2>
<p>Creates and returns a signing object, with the given algorithm. On
recent OpenSSL releases, <code>openssl list-public-key-algorithms</code> will
display the available signing algorithms. Examples are <code>&#39;RSA-SHA256&#39;</code>.
</p>
<h2>Class: Sign<span><a class="mark" href="#all_class_sign" id="all_class_sign">#</a></span></h2>
<p>Class for generating signatures.
</p>
<p>Returned by <code>crypto.createSign</code>.
</p>
<p>Sign objects are writable <a href="stream.html">streams</a>. The written data is
used to generate the signature. Once all of the data has been
written, the <code>sign</code> method will return the signature. The legacy
<code>update</code> method is also supported.
</p>
<h3>sign.update(data)<span><a class="mark" href="#all_sign_update_data" id="all_sign_update_data">#</a></span></h3>
<p>Updates the sign object with data. This can be called many times
with new data as it is streamed.
</p>
<h3>sign.sign(private_key, [output_format])<span><a class="mark" href="#all_sign_sign_private_key_output_format" id="all_sign_sign_private_key_output_format">#</a></span></h3>
<p>Calculates the signature on all the updated data passed through the
sign. <code>private_key</code> is a string containing the PEM encoded private
key for signing.
</p>
<p>Returns the signature in <code>output_format</code> which can be <code>&#39;binary&#39;</code>,
<code>&#39;hex&#39;</code> or <code>&#39;base64&#39;</code>. If no encoding is provided, then a buffer is
returned.
</p>
<p>Note: <code>sign</code> object can not be used after <code>sign()</code> method has been
called.
</p>
<h2>crypto.createVerify(algorithm)<span><a class="mark" href="#all_crypto_createverify_algorithm" id="all_crypto_createverify_algorithm">#</a></span></h2>
<p>Creates and returns a verification object, with the given algorithm.
This is the mirror of the signing object above.
</p>
<h2>Class: Verify<span><a class="mark" href="#all_class_verify" id="all_class_verify">#</a></span></h2>
<p>Class for verifying signatures.
</p>
<p>Returned by <code>crypto.createVerify</code>.
</p>
<p>Verify objects are writable <a href="stream.html">streams</a>. The written data
is used to validate against the supplied signature. Once all of the
data has been written, the <code>verify</code> method will return true if the
supplied signature is valid. The legacy <code>update</code> method is also
supported.
</p>
<h3>verifier.update(data)<span><a class="mark" href="#all_verifier_update_data" id="all_verifier_update_data">#</a></span></h3>
<p>Updates the verifier object with data. This can be called many times
with new data as it is streamed.
</p>
<h3>verifier.verify(object, signature, [signature_format])<span><a class="mark" href="#all_verifier_verify_object_signature_signature_format" id="all_verifier_verify_object_signature_signature_format">#</a></span></h3>
<p>Verifies the signed data by using the <code>object</code> and <code>signature</code>.
<code>object</code> is a string containing a PEM encoded object, which can be
one of RSA public key, DSA public key, or X.509 certificate.
<code>signature</code> is the previously calculated signature for the data, in
the <code>signature_format</code> which can be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code> or <code>&#39;base64&#39;</code>.
If no encoding is specified, then a buffer is expected.
</p>
<p>Returns true or false depending on the validity of the signature for
the data and public key.
</p>
<p>Note: <code>verifier</code> object can not be used after <code>verify()</code> method has been
called.
</p>
<h2>crypto.createDiffieHellman(prime_length)<span><a class="mark" href="#all_crypto_creatediffiehellman_prime_length" id="all_crypto_creatediffiehellman_prime_length">#</a></span></h2>
<p>Creates a Diffie-Hellman key exchange object and generates a prime of
the given bit length. The generator used is <code>2</code>.
</p>
<h2>crypto.createDiffieHellman(prime, [encoding])<span><a class="mark" href="#all_crypto_creatediffiehellman_prime_encoding" id="all_crypto_creatediffiehellman_prime_encoding">#</a></span></h2>
<p>Creates a Diffie-Hellman key exchange object using the supplied prime.
The generator used is <code>2</code>. Encoding can be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>, or
<code>&#39;base64&#39;</code>. If no encoding is specified, then a buffer is expected.
</p>
<h2>Class: DiffieHellman<span><a class="mark" href="#all_class_diffiehellman" id="all_class_diffiehellman">#</a></span></h2>
<p>The class for creating Diffie-Hellman key exchanges.
</p>
<p>Returned by <code>crypto.createDiffieHellman</code>.
</p>
<h3>diffieHellman.generateKeys([encoding])<span><a class="mark" href="#all_diffiehellman_generatekeys_encoding" id="all_diffiehellman_generatekeys_encoding">#</a></span></h3>
<p>Generates private and public Diffie-Hellman key values, and returns
the public key in the specified encoding. This key should be
transferred to the other party. Encoding can be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>,
or <code>&#39;base64&#39;</code>. If no encoding is provided, then a buffer is returned.
</p>
<h3>diffieHellman.computeSecret(other_public_key, [input_encoding], [output_encoding])<span><a class="mark" href="#all_diffiehellman_computesecret_other_public_key_input_encoding_output_encoding" id="all_diffiehellman_computesecret_other_public_key_input_encoding_output_encoding">#</a></span></h3>
<p>Computes the shared secret using <code>other_public_key</code> as the other
party&#39;s public key and returns the computed shared secret. Supplied
key is interpreted using specified <code>input_encoding</code>, and secret is
encoded using specified <code>output_encoding</code>. Encodings can be
<code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>, or <code>&#39;base64&#39;</code>. If the input encoding is not
provided, then a buffer is expected.
</p>
<p>If no output encoding is given, then a buffer is returned.
</p>
<h3>diffieHellman.getPrime([encoding])<span><a class="mark" href="#all_diffiehellman_getprime_encoding" id="all_diffiehellman_getprime_encoding">#</a></span></h3>
<p>Returns the Diffie-Hellman prime in the specified encoding, which can
be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>, or <code>&#39;base64&#39;</code>. If no encoding is provided,
then a buffer is returned.
</p>
<h3>diffieHellman.getGenerator([encoding])<span><a class="mark" href="#all_diffiehellman_getgenerator_encoding" id="all_diffiehellman_getgenerator_encoding">#</a></span></h3>
<p>Returns the Diffie-Hellman prime in the specified encoding, which can
be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>, or <code>&#39;base64&#39;</code>. If no encoding is provided,
then a buffer is returned.
</p>
<h3>diffieHellman.getPublicKey([encoding])<span><a class="mark" href="#all_diffiehellman_getpublickey_encoding" id="all_diffiehellman_getpublickey_encoding">#</a></span></h3>
<p>Returns the Diffie-Hellman public key in the specified encoding, which
can be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>, or <code>&#39;base64&#39;</code>. If no encoding is provided,
then a buffer is returned.
</p>
<h3>diffieHellman.getPrivateKey([encoding])<span><a class="mark" href="#all_diffiehellman_getprivatekey_encoding" id="all_diffiehellman_getprivatekey_encoding">#</a></span></h3>
<p>Returns the Diffie-Hellman private key in the specified encoding,
which can be <code>&#39;binary&#39;</code>, <code>&#39;hex&#39;</code>, or <code>&#39;base64&#39;</code>. If no encoding is
provided, then a buffer is returned.
</p>
<h3>diffieHellman.setPublicKey(public_key, [encoding])<span><a class="mark" href="#all_diffiehellman_setpublickey_public_key_encoding" id="all_diffiehellman_setpublickey_public_key_encoding">#</a></span></h3>
<p>Sets the Diffie-Hellman public key. Key encoding can be <code>&#39;binary&#39;</code>,
<code>&#39;hex&#39;</code> or <code>&#39;base64&#39;</code>. If no encoding is provided, then a buffer is
expected.
</p>
<h3>diffieHellman.setPrivateKey(private_key, [encoding])<span><a class="mark" href="#all_diffiehellman_setprivatekey_private_key_encoding" id="all_diffiehellman_setprivatekey_private_key_encoding">#</a></span></h3>
<p>Sets the Diffie-Hellman private key. Key encoding can be <code>&#39;binary&#39;</code>,
<code>&#39;hex&#39;</code> or <code>&#39;base64&#39;</code>. If no encoding is provided, then a buffer is
expected.
</p>
<h2>crypto.getDiffieHellman(group_name)<span><a class="mark" href="#all_crypto_getdiffiehellman_group_name" id="all_crypto_getdiffiehellman_group_name">#</a></span></h2>
<p>Creates a predefined Diffie-Hellman key exchange object. The
supported groups are: <code>&#39;modp1&#39;</code>, <code>&#39;modp2&#39;</code>, <code>&#39;modp5&#39;</code> (defined in <a href="http://www.rfc-editor.org/rfc/rfc2412.txt">RFC
2412</a>) and <code>&#39;modp14&#39;</code>, <code>&#39;modp15&#39;</code>, <code>&#39;modp16&#39;</code>, <code>&#39;modp17&#39;</code>,
<code>&#39;modp18&#39;</code> (defined in <a href="http://www.rfc-editor.org/rfc/rfc3526.txt">RFC 3526</a>). The returned object mimics the
interface of objects created by <a href="#crypto_crypto_creatediffiehellman_prime_encoding">crypto.createDiffieHellman()</a>
above, but will not allow to change the keys (with
<a href="#crypto_diffiehellman_setpublickey_public_key_encoding">diffieHellman.setPublicKey()</a> for example). The advantage of using
this routine is that the parties don&#39;t have to generate nor exchange
group modulus beforehand, saving both processor and communication
time.
</p>
<p>Example (obtaining a shared secret):
</p>
<pre><code>var crypto = require(&#39;crypto&#39;);
var alice = crypto.getDiffieHellman(&#39;modp5&#39;);
var bob = crypto.getDiffieHellman(&#39;modp5&#39;);
alice.generateKeys();
bob.generateKeys();
var alice_secret = alice.computeSecret(bob.getPublicKey(), null, &#39;hex&#39;);
var bob_secret = bob.computeSecret(alice.getPublicKey(), null, &#39;hex&#39;);
/* alice_secret and bob_secret should be the same */
console.log(alice_secret == bob_secret);</code></pre>
<h2>crypto.pbkdf2(password, salt, iterations, keylen, callback)<span><a class="mark" href="#all_crypto_pbkdf2_password_salt_iterations_keylen_callback" id="all_crypto_pbkdf2_password_salt_iterations_keylen_callback">#</a></span></h2>
<p>Asynchronous PBKDF2 applies pseudorandom function HMAC-SHA1 to derive
a key of given length from the given password, salt and iterations.
The callback gets two arguments <code>(err, derivedKey)</code>.
</p>
<h2>crypto.pbkdf2Sync(password, salt, iterations, keylen)<span><a class="mark" href="#all_crypto_pbkdf2sync_password_salt_iterations_keylen" id="all_crypto_pbkdf2sync_password_salt_iterations_keylen">#</a></span></h2>
<p>Synchronous PBKDF2 function. Returns derivedKey or throws error.
</p>
<h2>crypto.randomBytes(size, [callback])<span><a class="mark" href="#all_crypto_randombytes_size_callback" id="all_crypto_randombytes_size_callback">#</a></span></h2>
<p>Generates cryptographically strong pseudo-random data. Usage:
</p>
<pre><code>// async
crypto.randomBytes(256, function(ex, buf) {
if (ex) throw ex;
console.log(&#39;Have %d bytes of random data: %s&#39;, buf.length, buf);
});
// sync
try {
var buf = crypto.randomBytes(256);
console.log(&#39;Have %d bytes of random data: %s&#39;, buf.length, buf);
} catch (ex) {
// handle error
// most likely, entropy sources are drained
}</code></pre>
<p>NOTE: Will throw error or invoke callback with error, if there is not enough
accumulated entropy to generate cryptographically strong data. In other words,
<code>crypto.randomBytes</code> without callback will not block even if all entropy sources
are drained.
</p>
<h2>crypto.pseudoRandomBytes(size, [callback])<span><a class="mark" href="#all_crypto_pseudorandombytes_size_callback" id="all_crypto_pseudorandombytes_size_callback">#</a></span></h2>
<p>Generates <em>non</em>-cryptographically strong pseudo-random data. The data
returned will be unique if it is sufficiently long, but is not
necessarily unpredictable. For this reason, the output of this
function should never be used where unpredictability is important,
such as in the generation of encryption keys.
</p>
<p>Usage is otherwise identical to <code>crypto.randomBytes</code>.
</p>
<h2>crypto.DEFAULT_ENCODING<span><a class="mark" href="#all_crypto_default_encoding" id="all_crypto_default_encoding">#</a></span></h2>
<p>The default encoding to use for functions that can take either strings
or buffers. The default value is <code>&#39;buffer&#39;</code>, which makes it default
to using Buffer objects. This is here to make the crypto module more
easily compatible with legacy programs that expected <code>&#39;binary&#39;</code> to be
the default encoding.
</p>
<p>Note that new programs will probably expect buffers, so only use this
as a temporary measure.
</p>
<h2>Recent API Changes<span><a class="mark" href="#all_recent_api_changes" id="all_recent_api_changes">#</a></span></h2>
<p>The Crypto module was added to Node before there was the concept of a
unified Stream API, and before there were Buffer objects for handling
binary data.
</p>
<p>As such, the streaming classes don&#39;t have the typical methods found on
other Node classes, and many methods accepted and returned
Binary-encoded strings by default rather than Buffers. This was
changed to use Buffers by default instead.
</p>
<p>This is a breaking change for some use cases, but not all.
</p>
<p>For example, if you currently use the default arguments to the Sign
class, and then pass the results to the Verify class, without ever
inspecting the data, then it will continue to work as before. Where
you once got a binary string and then presented the binary string to
the Verify object, you&#39;ll now get a Buffer, and present the Buffer to
the Verify object.
</p>
<p>However, if you were doing things with the string data that will not
work properly on Buffers (such as, concatenating them, storing in
databases, etc.), or you are passing binary strings to the crypto
functions without an encoding argument, then you will need to start
providing encoding arguments to specify which encoding you&#39;d like to
use. To switch to the previous style of using binary strings by
default, set the <code>crypto.DEFAULT_ENCODING</code> field to &#39;binary&#39;. Note
that new programs will probably expect buffers, so only use this as a
temporary measure.
</p>
<h1>TLS (SSL)<span><a class="mark" href="#all_tls_ssl" id="all_tls_ssl">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>Use <code>require(&#39;tls&#39;)</code> to access this module.
</p>
<p>The <code>tls</code> module uses OpenSSL to provide Transport Layer Security and/or
Secure Socket Layer: encrypted stream communication.
</p>
<p>TLS/SSL is a public/private key infrastructure. Each client and each
server must have a private key. A private key is created like this
</p>
<pre><code>openssl genrsa -out ryans-key.pem 1024</code></pre>
<p>All severs and some clients need to have a certificate. Certificates are public
keys signed by a Certificate Authority or self-signed. The first step to
getting a certificate is to create a &quot;Certificate Signing Request&quot; (CSR)
file. This is done with:
</p>
<pre><code>openssl req -new -key ryans-key.pem -out ryans-csr.pem</code></pre>
<p>To create a self-signed certificate with the CSR, do this:
</p>
<pre><code>openssl x509 -req -in ryans-csr.pem -signkey ryans-key.pem -out ryans-cert.pem</code></pre>
<p>Alternatively you can send the CSR to a Certificate Authority for signing.
</p>
<p>(TODO: docs on creating a CA, for now interested users should just look at
<code>test/fixtures/keys/Makefile</code> in the Node source code)
</p>
<p>To create .pfx or .p12, do this:
</p>
<pre><code>openssl pkcs12 -export -in agent5-cert.pem -inkey agent5-key.pem \
-certfile ca-cert.pem -out agent5.pfx</code></pre>
<ul>
<li><code>in</code>: certificate</li>
<li><code>inkey</code>: private key</li>
<li><code>certfile</code>: all CA certs concatenated in one file like
<code>cat ca1-cert.pem ca2-cert.pem &gt; ca-cert.pem</code></li>
</ul>
<h2>Client-initiated renegotiation attack mitigation<span><a class="mark" href="#all_client_initiated_renegotiation_attack_mitigation" id="all_client_initiated_renegotiation_attack_mitigation">#</a></span></h2>
<!-- type=misc -->
<p>The TLS protocol lets the client renegotiate certain aspects of the TLS session.
Unfortunately, session renegotiation requires a disproportional amount of
server-side resources, which makes it a potential vector for denial-of-service
attacks.
</p>
<p>To mitigate this, renegotiations are limited to three times every 10 minutes. An
error is emitted on the <a href="#tls_class_tls_cleartextstream">CleartextStream</a> instance when the threshold is
exceeded. The limits are configurable:
</p>
<ul>
<li><p><code>tls.CLIENT_RENEG_LIMIT</code>: renegotiation limit, default is 3.</p>
</li>
<li><p><code>tls.CLIENT_RENEG_WINDOW</code>: renegotiation window in seconds, default is
10 minutes.</p>
</li>
</ul>
<p>Don&#39;t change the defaults unless you know what you are doing.
</p>
<p>To test your server, connect to it with <code>openssl s_client -connect address:port</code>
and tap <code>R&lt;CR&gt;</code> (that&#39;s the letter <code>R</code> followed by a carriage return) a few
times.
</p>
<h2>NPN and SNI<span><a class="mark" href="#all_npn_and_sni" id="all_npn_and_sni">#</a></span></h2>
<!-- type=misc -->
<p>NPN (Next Protocol Negotiation) and SNI (Server Name Indication) are TLS
handshake extensions allowing you:
</p>
<ul>
<li>NPN - to use one TLS server for multiple protocols (HTTP, SPDY)</li>
<li>SNI - to use one TLS server for multiple hostnames with different SSL
certificates.</li>
</ul>
<h2>tls.getCiphers()<span><a class="mark" href="#all_tls_getciphers" id="all_tls_getciphers">#</a></span></h2>
<p>Returns an array with the names of the supported SSL ciphers.
</p>
<p>Example:
</p>
<pre><code>var ciphers = tls.getCiphers();
console.log(ciphers); // [&#39;AES128-SHA&#39;, &#39;AES256-SHA&#39;, ...]</code></pre>
<h2>tls.createServer(options, [secureConnectionListener])<span><a class="mark" href="#all_tls_createserver_options_secureconnectionlistener" id="all_tls_createserver_options_secureconnectionlistener">#</a></span></h2>
<p>Creates a new <a href="#tls_class_tls_server">tls.Server</a>. The <code>connectionListener</code> argument is
automatically set as a listener for the <a href="#tls_event_secureconnection">secureConnection</a> event. The
<code>options</code> object has these possibilities:
</p>
<ul>
<li><p><code>pfx</code>: A string or <code>Buffer</code> containing the private key, certificate and
CA certs of the server in PFX or PKCS12 format. (Mutually exclusive with
the <code>key</code>, <code>cert</code> and <code>ca</code> options.)</p>
</li>
<li><p><code>key</code>: A string or <code>Buffer</code> containing the private key of the server in
PEM format. (Required)</p>
</li>
<li><p><code>passphrase</code>: A string of passphrase for the private key or pfx.</p>
</li>
<li><p><code>cert</code>: A string or <code>Buffer</code> containing the certificate key of the server in
PEM format. (Required)</p>
</li>
<li><p><code>ca</code>: An array of strings or <code>Buffer</code>s of trusted certificates in PEM
format. If this is omitted several well known &quot;root&quot; CAs will be used,
like VeriSign. These are used to authorize connections.</p>
</li>
<li><p><code>crl</code> : Either a string or list of strings of PEM encoded CRLs (Certificate
Revocation List)</p>
</li>
<li><p><code>ciphers</code>: A string describing the ciphers to use or exclude.</p>
<p>To mitigate <a href="http://blog.ivanristic.com/2011/10/mitigating-the-beast-attack-on-tls.html">BEAST attacks</a> it is recommended that you use this option in
conjunction with the <code>honorCipherOrder</code> option described below to
prioritize the non-CBC cipher.</p>
<p>Defaults to <code>AES128-GCM-SHA256:RC4:HIGH:!MD5:!aNULL:!EDH</code>.
Consult the <a href="http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT">OpenSSL cipher list format documentation</a> for details on the
format. ECDH (Elliptic Curve Diffie-Hellman) ciphers are not yet supported.</p>
</li>
</ul>
<pre><code>`AES128-GCM-SHA256` is used when node.js is linked against OpenSSL 1.0.1
or newer and the client speaks TLS 1.2, RC4 is used as a secure fallback.
**NOTE**: Previous revisions of this section suggested `AES256-SHA` as an
acceptable cipher. Unfortunately, `AES256-SHA` is a CBC cipher and therefore
susceptible to BEAST attacks. Do *not* use it.</code></pre>
<ul>
<li><p><code>handshakeTimeout</code>: Abort the connection if the SSL/TLS handshake does not
finish in this many milliseconds. The default is 120 seconds.</p>
<p>A <code>&#39;clientError&#39;</code> is emitted on the <code>tls.Server</code> object whenever a handshake
times out.</p>
</li>
<li><p><code>honorCipherOrder</code> : When choosing a cipher, use the server&#39;s preferences
instead of the client preferences.</p>
<p>Note that if SSLv2 is used, the server will send its list of preferences
to the client, and the client chooses the cipher.</p>
<p>Although, this option is disabled by default, it is <em>recommended</em> that you
use this option in conjunction with the <code>ciphers</code> option to mitigate
BEAST attacks.</p>
</li>
<li><p><code>requestCert</code>: If <code>true</code> the server will request a certificate from
clients that connect and attempt to verify that certificate. Default:
<code>false</code>.</p>
</li>
<li><p><code>rejectUnauthorized</code>: If <code>true</code> the server will reject any connection
which is not authorized with the list of supplied CAs. This option only
has an effect if <code>requestCert</code> is <code>true</code>. Default: <code>false</code>.</p>
</li>
<li><p><code>NPNProtocols</code>: An array or <code>Buffer</code> of possible NPN protocols. (Protocols
should be ordered by their priority).</p>
</li>
<li><p><code>SNICallback</code>: A function that will be called if client supports SNI TLS
extension. Only one argument will be passed to it: <code>servername</code>. And
<code>SNICallback</code> should return SecureContext instance.
(You can use <code>crypto.createCredentials(...).context</code> to get proper
SecureContext). If <code>SNICallback</code> wasn&#39;t provided - default callback with
high-level API will be used (see below).</p>
</li>
<li><p><code>sessionIdContext</code>: A string containing a opaque identifier for session
resumption. If <code>requestCert</code> is <code>true</code>, the default is MD5 hash value
generated from command-line. Otherwise, the default is not provided.</p>
</li>
<li><p><code>secureProtocol</code>: The SSL method to use, e.g. <code>SSLv3_method</code> to force
SSL version 3. The possible values depend on your installation of
OpenSSL and are defined in the constant <a href="http://www.openssl.org/docs/ssl/ssl.html#DEALING_WITH_PROTOCOL_METHODS">SSL_METHODS</a>.</p>
</li>
</ul>
<p>Here is a simple example echo server:
</p>
<pre><code>var tls = require(&#39;tls&#39;);
var fs = require(&#39;fs&#39;);
var options = {
key: fs.readFileSync(&#39;server-key.pem&#39;),
cert: fs.readFileSync(&#39;server-cert.pem&#39;),
// This is necessary only if using the client certificate authentication.
requestCert: true,
// This is necessary only if the client uses the self-signed certificate.
ca: [ fs.readFileSync(&#39;client-cert.pem&#39;) ]
};
var server = tls.createServer(options, function(cleartextStream) {
console.log(&#39;server connected&#39;,
cleartextStream.authorized ? &#39;authorized&#39; : &#39;unauthorized&#39;);
cleartextStream.write(&quot;welcome!\n&quot;);
cleartextStream.setEncoding(&#39;utf8&#39;);
cleartextStream.pipe(cleartextStream);
});
server.listen(8000, function() {
console.log(&#39;server bound&#39;);
});</code></pre>
<p>Or
</p>
<pre><code>var tls = require(&#39;tls&#39;);
var fs = require(&#39;fs&#39;);
var options = {
pfx: fs.readFileSync(&#39;server.pfx&#39;),
// This is necessary only if using the client certificate authentication.
requestCert: true,
};
var server = tls.createServer(options, function(cleartextStream) {
console.log(&#39;server connected&#39;,
cleartextStream.authorized ? &#39;authorized&#39; : &#39;unauthorized&#39;);
cleartextStream.write(&quot;welcome!\n&quot;);
cleartextStream.setEncoding(&#39;utf8&#39;);
cleartextStream.pipe(cleartextStream);
});
server.listen(8000, function() {
console.log(&#39;server bound&#39;);
});</code></pre>
<p>You can test this server by connecting to it with <code>openssl s_client</code>:
</p>
<pre><code>openssl s_client -connect 127.0.0.1:8000</code></pre>
<h2>tls.SLAB_BUFFER_SIZE<span><a class="mark" href="#all_tls_slab_buffer_size" id="all_tls_slab_buffer_size">#</a></span></h2>
<p>Size of slab buffer used by all tls servers and clients.
Default: <code>10 * 1024 * 1024</code>.
</p>
<p>Don&#39;t change the defaults unless you know what you are doing.
</p>
<h2>tls.connect(options, [callback])<span><a class="mark" href="#all_tls_connect_options_callback" id="all_tls_connect_options_callback">#</a></span></h2>
<h2>tls.connect(port, [host], [options], [callback])<span><a class="mark" href="#all_tls_connect_port_host_options_callback" id="all_tls_connect_port_host_options_callback">#</a></span></h2>
<p>Creates a new client connection to the given <code>port</code> and <code>host</code> (old API) or
<code>options.port</code> and <code>options.host</code>. (If <code>host</code> is omitted, it defaults to
<code>localhost</code>.) <code>options</code> should be an object which specifies:
</p>
<ul>
<li><p><code>host</code>: Host the client should connect to</p>
</li>
<li><p><code>port</code>: Port the client should connect to</p>
</li>
<li><p><code>socket</code>: Establish secure connection on a given socket rather than
creating a new socket. If this option is specified, <code>host</code> and <code>port</code>
are ignored.</p>
</li>
<li><p><code>pfx</code>: A string or <code>Buffer</code> containing the private key, certificate and
CA certs of the server in PFX or PKCS12 format.</p>
</li>
<li><p><code>key</code>: A string or <code>Buffer</code> containing the private key of the client in
PEM format.</p>
</li>
<li><p><code>passphrase</code>: A string of passphrase for the private key or pfx.</p>
</li>
<li><p><code>cert</code>: A string or <code>Buffer</code> containing the certificate key of the client in
PEM format.</p>
</li>
<li><p><code>ca</code>: An array of strings or <code>Buffer</code>s of trusted certificates in PEM
format. If this is omitted several well known &quot;root&quot; CAs will be used,
like VeriSign. These are used to authorize connections.</p>
</li>
<li><p><code>rejectUnauthorized</code>: If <code>true</code>, the server certificate is verified against
the list of supplied CAs. An <code>&#39;error&#39;</code> event is emitted if verification
fails. Default: <code>true</code>.</p>
</li>
<li><p><code>NPNProtocols</code>: An array of strings or <code>Buffer</code>s containing supported NPN
protocols. <code>Buffer</code>s should have following format: <code>0x05hello0x05world</code>,
where first byte is next protocol name&#39;s length. (Passing array should
usually be much simpler: <code>[&#39;hello&#39;, &#39;world&#39;]</code>.)</p>
</li>
<li><p><code>servername</code>: Servername for SNI (Server Name Indication) TLS extension.</p>
</li>
<li><p><code>secureProtocol</code>: The SSL method to use, e.g. <code>SSLv3_method</code> to force
SSL version 3. The possible values depend on your installation of
OpenSSL and are defined in the constant <a href="http://www.openssl.org/docs/ssl/ssl.html#DEALING_WITH_PROTOCOL_METHODS">SSL_METHODS</a>.</p>
</li>
</ul>
<p>The <code>callback</code> parameter will be added as a listener for the
<a href="#tls_event_secureconnect">&#39;secureConnect&#39;</a> event.
</p>
<p><code>tls.connect()</code> returns a <a href="#tls_class_tls_cleartextstream">CleartextStream</a> object.
</p>
<p>Here is an example of a client of echo server as described previously:
</p>
<pre><code>var tls = require(&#39;tls&#39;);
var fs = require(&#39;fs&#39;);
var options = {
// These are necessary only if using the client certificate authentication
key: fs.readFileSync(&#39;client-key.pem&#39;),
cert: fs.readFileSync(&#39;client-cert.pem&#39;),
// This is necessary only if the server uses the self-signed certificate
ca: [ fs.readFileSync(&#39;server-cert.pem&#39;) ]
};
var cleartextStream = tls.connect(8000, options, function() {
console.log(&#39;client connected&#39;,
cleartextStream.authorized ? &#39;authorized&#39; : &#39;unauthorized&#39;);
process.stdin.pipe(cleartextStream);
process.stdin.resume();
});
cleartextStream.setEncoding(&#39;utf8&#39;);
cleartextStream.on(&#39;data&#39;, function(data) {
console.log(data);
});
cleartextStream.on(&#39;end&#39;, function() {
server.close();
});</code></pre>
<p>Or
</p>
<pre><code>var tls = require(&#39;tls&#39;);
var fs = require(&#39;fs&#39;);
var options = {
pfx: fs.readFileSync(&#39;client.pfx&#39;)
};
var cleartextStream = tls.connect(8000, options, function() {
console.log(&#39;client connected&#39;,
cleartextStream.authorized ? &#39;authorized&#39; : &#39;unauthorized&#39;);
process.stdin.pipe(cleartextStream);
process.stdin.resume();
});
cleartextStream.setEncoding(&#39;utf8&#39;);
cleartextStream.on(&#39;data&#39;, function(data) {
console.log(data);
});
cleartextStream.on(&#39;end&#39;, function() {
server.close();
});</code></pre>
<h2>tls.createSecurePair([credentials], [isServer], [requestCert], [rejectUnauthorized])<span><a class="mark" href="#all_tls_createsecurepair_credentials_isserver_requestcert_rejectunauthorized" id="all_tls_createsecurepair_credentials_isserver_requestcert_rejectunauthorized">#</a></span></h2>
<p>Creates a new secure pair object with two streams, one of which reads/writes
encrypted data, and one reads/writes cleartext data.
Generally the encrypted one is piped to/from an incoming encrypted data stream,
and the cleartext one is used as a replacement for the initial encrypted stream.
</p>
<ul>
<li><p><code>credentials</code>: A credentials object from crypto.createCredentials( ... )</p>
</li>
<li><p><code>isServer</code>: A boolean indicating whether this tls connection should be
opened as a server or a client.</p>
</li>
<li><p><code>requestCert</code>: A boolean indicating whether a server should request a
certificate from a connecting client. Only applies to server connections.</p>
</li>
<li><p><code>rejectUnauthorized</code>: A boolean indicating whether a server should
automatically reject clients with invalid certificates. Only applies to
servers with <code>requestCert</code> enabled.</p>
</li>
</ul>
<p><code>tls.createSecurePair()</code> returns a SecurePair object with [cleartext][] and
<code>encrypted</code> stream properties.
</p>
<h2>Class: SecurePair<span><a class="mark" href="#all_class_securepair" id="all_class_securepair">#</a></span></h2>
<p>Returned by tls.createSecurePair.
</p>
<h3>Event: &#39;secure&#39;<span><a class="mark" href="#all_event_secure" id="all_event_secure">#</a></span></h3>
<p>The event is emitted from the SecurePair once the pair has successfully
established a secure connection.
</p>
<p>Similarly to the checking for the server &#39;secureConnection&#39; event,
pair.cleartext.authorized should be checked to confirm whether the certificate
used properly authorized.
</p>
<h2>Class: tls.Server<span><a class="mark" href="#all_class_tls_server" id="all_class_tls_server">#</a></span></h2>
<p>This class is a subclass of <code>net.Server</code> and has the same methods on it.
Instead of accepting just raw TCP connections, this accepts encrypted
connections using TLS or SSL.
</p>
<h3>Event: &#39;secureConnection&#39;<span><a class="mark" href="#all_event_secureconnection" id="all_event_secureconnection">#</a></span></h3>
<p><code>function (cleartextStream) {}</code>
</p>
<p>This event is emitted after a new connection has been successfully
handshaked. The argument is a instance of <a href="#tls_class_tls_cleartextstream">CleartextStream</a>. It has all the
common stream methods and events.
</p>
<p><code>cleartextStream.authorized</code> is a boolean value which indicates if the
client has verified by one of the supplied certificate authorities for the
server. If <code>cleartextStream.authorized</code> is false, then
<code>cleartextStream.authorizationError</code> is set to describe how authorization
failed. Implied but worth mentioning: depending on the settings of the TLS
server, you unauthorized connections may be accepted.
<code>cleartextStream.npnProtocol</code> is a string containing selected NPN protocol.
<code>cleartextStream.servername</code> is a string containing servername requested with
SNI.
</p>
<h3>Event: &#39;clientError&#39;<span><a class="mark" href="#all_event_clienterror" id="all_event_clienterror">#</a></span></h3>
<p><code>function (exception, securePair) { }</code>
</p>
<p>When a client connection emits an &#39;error&#39; event before secure connection is
established - it will be forwarded here.
</p>
<p><code>securePair</code> is the <code>tls.SecurePair</code> that the error originated from.
</p>
<h3>Event: &#39;newSession&#39;<span><a class="mark" href="#all_event_newsession" id="all_event_newsession">#</a></span></h3>
<p><code>function (sessionId, sessionData) { }</code>
</p>
<p>Emitted on creation of TLS session. May be used to store sessions in external
storage.
</p>
<h3>Event: &#39;resumeSession&#39;<span><a class="mark" href="#all_event_resumesession" id="all_event_resumesession">#</a></span></h3>
<p><code>function (sessionId, callback) { }</code>
</p>
<p>Emitted when client wants to resume previous TLS session. Event listener may
perform lookup in external storage using given <code>sessionId</code>, and invoke
<code>callback(null, sessionData)</code> once finished. If session can&#39;t be resumed
(i.e. doesn&#39;t exist in storage) one may call <code>callback(null, null)</code>. Calling
<code>callback(err)</code> will terminate incoming connection and destroy socket.
</p>
<h3>server.listen(port, [host], [callback])<span><a class="mark" href="#all_server_listen_port_host_callback" id="all_server_listen_port_host_callback">#</a></span></h3>
<p>Begin accepting connections on the specified <code>port</code> and <code>host</code>. If the
<code>host</code> is omitted, the server will accept connections directed to any
IPv4 address (<code>INADDR_ANY</code>).
</p>
<p>This function is asynchronous. The last parameter <code>callback</code> will be called
when the server has been bound.
</p>
<p>See <code>net.Server</code> for more information.
</p>
<h3>server.close()<span><a class="mark" href="#all_server_close" id="all_server_close">#</a></span></h3>
<p>Stops the server from accepting new connections. This function is
asynchronous, the server is finally closed when the server emits a <code>&#39;close&#39;</code>
event.
</p>
<h3>server.address()<span><a class="mark" href="#all_server_address" id="all_server_address">#</a></span></h3>
<p>Returns the bound address, the address family name and port of the
server as reported by the operating system. See <a href="net.html#net_server_address">net.Server.address()</a> for
more information.
</p>
<h3>server.addContext(hostname, credentials)<span><a class="mark" href="#all_server_addcontext_hostname_credentials" id="all_server_addcontext_hostname_credentials">#</a></span></h3>
<p>Add secure context that will be used if client request&#39;s SNI hostname is
matching passed <code>hostname</code> (wildcards can be used). <code>credentials</code> can contain
<code>key</code>, <code>cert</code> and <code>ca</code>.
</p>
<h3>server.maxConnections<span><a class="mark" href="#all_server_maxconnections" id="all_server_maxconnections">#</a></span></h3>
<p>Set this property to reject connections when the server&#39;s connection count
gets high.
</p>
<h3>server.connections<span><a class="mark" href="#all_server_connections" id="all_server_connections">#</a></span></h3>
<p>The number of concurrent connections on the server.
</p>
<h2>Class: CryptoStream<span><a class="mark" href="#all_class_cryptostream" id="all_class_cryptostream">#</a></span></h2>
<p>This is an encrypted stream.
</p>
<h3>cryptoStream.bytesWritten<span><a class="mark" href="#all_cryptostream_byteswritten" id="all_cryptostream_byteswritten">#</a></span></h3>
<p>A proxy to the underlying socket&#39;s bytesWritten accessor, this will return
the total bytes written to the socket, <em>including the TLS overhead</em>.
</p>
<h2>Class: tls.CleartextStream<span><a class="mark" href="#all_class_tls_cleartextstream" id="all_class_tls_cleartextstream">#</a></span></h2>
<p>This is a stream on top of the <em>Encrypted</em> stream that makes it possible to
read/write an encrypted data as a cleartext data.
</p>
<p>This instance implements a duplex <a href="stream.html#stream_stream">Stream</a> interfaces. It has all the
common stream methods and events.
</p>
<p>A ClearTextStream is the <code>clear</code> member of a SecurePair object.
</p>
<h3>Event: &#39;secureConnect&#39;<span><a class="mark" href="#all_event_secureconnect" id="all_event_secureconnect">#</a></span></h3>
<p>This event is emitted after a new connection has been successfully handshaked.
The listener will be called no matter if the server&#39;s certificate was
authorized or not. It is up to the user to test <code>cleartextStream.authorized</code>
to see if the server certificate was signed by one of the specified CAs.
If <code>cleartextStream.authorized === false</code> then the error can be found in
<code>cleartextStream.authorizationError</code>. Also if NPN was used - you can check
<code>cleartextStream.npnProtocol</code> for negotiated protocol.
</p>
<h3>cleartextStream.authorized<span><a class="mark" href="#all_cleartextstream_authorized" id="all_cleartextstream_authorized">#</a></span></h3>
<p>A boolean that is <code>true</code> if the peer certificate was signed by one of the
specified CAs, otherwise <code>false</code>
</p>
<h3>cleartextStream.authorizationError<span><a class="mark" href="#all_cleartextstream_authorizationerror" id="all_cleartextstream_authorizationerror">#</a></span></h3>
<p>The reason why the peer&#39;s certificate has not been verified. This property
becomes available only when <code>cleartextStream.authorized === false</code>.
</p>
<h3>cleartextStream.getPeerCertificate()<span><a class="mark" href="#all_cleartextstream_getpeercertificate" id="all_cleartextstream_getpeercertificate">#</a></span></h3>
<p>Returns an object representing the peer&#39;s certificate. The returned object has
some properties corresponding to the field of the certificate.
</p>
<p>Example:
</p>
<pre><code>{ subject:
{ C: &#39;UK&#39;,
ST: &#39;Acknack Ltd&#39;,
L: &#39;Rhys Jones&#39;,
O: &#39;node.js&#39;,
OU: &#39;Test TLS Certificate&#39;,
CN: &#39;localhost&#39; },
issuer:
{ C: &#39;UK&#39;,
ST: &#39;Acknack Ltd&#39;,
L: &#39;Rhys Jones&#39;,
O: &#39;node.js&#39;,
OU: &#39;Test TLS Certificate&#39;,
CN: &#39;localhost&#39; },
valid_from: &#39;Nov 11 09:52:22 2009 GMT&#39;,
valid_to: &#39;Nov 6 09:52:22 2029 GMT&#39;,
fingerprint: &#39;2A:7A:C2:DD:E5:F9:CC:53:72:35:99:7A:02:5A:71:38:52:EC:8A:DF&#39; }</code></pre>
<p>If the peer does not provide a certificate, it returns <code>null</code> or an empty
object.
</p>
<h3>cleartextStream.getCipher()<span><a class="mark" href="#all_cleartextstream_getcipher" id="all_cleartextstream_getcipher">#</a></span></h3>
<p>Returns an object representing the cipher name and the SSL/TLS
protocol version of the current connection.
</p>
<p>Example:
{ name: &#39;AES256-SHA&#39;, version: &#39;TLSv1/SSLv3&#39; }
</p>
<p>See SSL_CIPHER_get_name() and SSL_CIPHER_get_version() in
<a href="http://www.openssl.org/docs/ssl/ssl.html#DEALING_WITH_CIPHERS">http://www.openssl.org/docs/ssl/ssl.html#DEALING_WITH_CIPHERS</a> for more
information.
</p>
<h3>cleartextStream.address()<span><a class="mark" href="#all_cleartextstream_address" id="all_cleartextstream_address">#</a></span></h3>
<p>Returns the bound address, the address family name and port of the
underlying socket as reported by the operating system. Returns an
object with three properties, e.g.
<code>{ port: 12346, family: &#39;IPv4&#39;, address: &#39;127.0.0.1&#39; }</code>
</p>
<h3>cleartextStream.remoteAddress<span><a class="mark" href="#all_cleartextstream_remoteaddress" id="all_cleartextstream_remoteaddress">#</a></span></h3>
<p>The string representation of the remote IP address. For example,
<code>&#39;74.125.127.100&#39;</code> or <code>&#39;2001:4860:a005::68&#39;</code>.
</p>
<h3>cleartextStream.remotePort<span><a class="mark" href="#all_cleartextstream_remoteport" id="all_cleartextstream_remoteport">#</a></span></h3>
<p>The numeric representation of the remote port. For example, <code>443</code>.
</p>
<h1>StringDecoder<span><a class="mark" href="#all_stringdecoder" id="all_stringdecoder">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>To use this module, do <code>require(&#39;string_decoder&#39;)</code>. StringDecoder decodes a
buffer to a string. It is a simple interface to <code>buffer.toString()</code> but provides
additional support for utf8.
</p>
<pre><code>var StringDecoder = require(&#39;string_decoder&#39;).StringDecoder;
var decoder = new StringDecoder(&#39;utf8&#39;);
var cent = new Buffer([0xC2, 0xA2]);
console.log(decoder.write(cent));
var euro = new Buffer([0xE2, 0x82, 0xAC]);
console.log(decoder.write(euro));</code></pre>
<h2>Class: StringDecoder<span><a class="mark" href="#all_class_stringdecoder" id="all_class_stringdecoder">#</a></span></h2>
<p>Accepts a single argument, <code>encoding</code> which defaults to <code>utf8</code>.
</p>
<h3>decoder.write(buffer)<span><a class="mark" href="#all_decoder_write_buffer" id="all_decoder_write_buffer">#</a></span></h3>
<p>Returns a decoded string.
</p>
<h3>decoder.end()<span><a class="mark" href="#all_decoder_end" id="all_decoder_end">#</a></span></h3>
<p>Returns any trailing bytes that were left in the buffer.
</p>
<h1>File System<span><a class="mark" href="#all_file_system" id="all_file_system">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><!--name=fs-->
<p>File I/O is provided by simple wrappers around standard POSIX functions. To
use this module do <code>require(&#39;fs&#39;)</code>. All the methods have asynchronous and
synchronous forms.
</p>
<p>The asynchronous form always take a completion callback as its last argument.
The arguments passed to the completion callback depend on the method, but the
first argument is always reserved for an exception. If the operation was
completed successfully, then the first argument will be <code>null</code> or <code>undefined</code>.
</p>
<p>When using the synchronous form any exceptions are immediately thrown.
You can use try/catch to handle exceptions or allow them to bubble up.
</p>
<p>Here is an example of the asynchronous version:
</p>
<pre><code>var fs = require(&#39;fs&#39;);
fs.unlink(&#39;/tmp/hello&#39;, function (err) {
if (err) throw err;
console.log(&#39;successfully deleted /tmp/hello&#39;);
});</code></pre>
<p>Here is the synchronous version:
</p>
<pre><code>var fs = require(&#39;fs&#39;);
fs.unlinkSync(&#39;/tmp/hello&#39;)
console.log(&#39;successfully deleted /tmp/hello&#39;);</code></pre>
<p>With the asynchronous methods there is no guaranteed ordering. So the
following is prone to error:
</p>
<pre><code>fs.rename(&#39;/tmp/hello&#39;, &#39;/tmp/world&#39;, function (err) {
if (err) throw err;
console.log(&#39;renamed complete&#39;);
});
fs.stat(&#39;/tmp/world&#39;, function (err, stats) {
if (err) throw err;
console.log(&#39;stats: &#39; + JSON.stringify(stats));
});</code></pre>
<p>It could be that <code>fs.stat</code> is executed before <code>fs.rename</code>.
The correct way to do this is to chain the callbacks.
</p>
<pre><code>fs.rename(&#39;/tmp/hello&#39;, &#39;/tmp/world&#39;, function (err) {
if (err) throw err;
fs.stat(&#39;/tmp/world&#39;, function (err, stats) {
if (err) throw err;
console.log(&#39;stats: &#39; + JSON.stringify(stats));
});
});</code></pre>
<p>In busy processes, the programmer is <em>strongly encouraged</em> to use the
asynchronous versions of these calls. The synchronous versions will block
the entire process until they complete--halting all connections.
</p>
<p>Relative path to filename can be used, remember however that this path will be
relative to <code>process.cwd()</code>.
</p>
<p>Most fs functions let you omit the callback argument. If you do, a default
callback is used that ignores errors, but prints a deprecation
warning.
</p>
<p><strong>IMPORTANT</strong>: Omitting the callback is deprecated. v0.12 will throw the
errors as exceptions.
</p>
<h2>fs.rename(oldPath, newPath, callback)<span><a class="mark" href="#all_fs_rename_oldpath_newpath_callback" id="all_fs_rename_oldpath_newpath_callback">#</a></span></h2>
<p>Asynchronous rename(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.renameSync(oldPath, newPath)<span><a class="mark" href="#all_fs_renamesync_oldpath_newpath" id="all_fs_renamesync_oldpath_newpath">#</a></span></h2>
<p>Synchronous rename(2).
</p>
<h2>fs.ftruncate(fd, len, callback)<span><a class="mark" href="#all_fs_ftruncate_fd_len_callback" id="all_fs_ftruncate_fd_len_callback">#</a></span></h2>
<p>Asynchronous ftruncate(2). No arguments other than a possible exception are
given to the completion callback.
</p>
<h2>fs.ftruncateSync(fd, len)<span><a class="mark" href="#all_fs_ftruncatesync_fd_len" id="all_fs_ftruncatesync_fd_len">#</a></span></h2>
<p>Synchronous ftruncate(2).
</p>
<h2>fs.truncate(path, len, callback)<span><a class="mark" href="#all_fs_truncate_path_len_callback" id="all_fs_truncate_path_len_callback">#</a></span></h2>
<p>Asynchronous truncate(2). No arguments other than a possible exception are
given to the completion callback.
</p>
<h2>fs.truncateSync(path, len)<span><a class="mark" href="#all_fs_truncatesync_path_len" id="all_fs_truncatesync_path_len">#</a></span></h2>
<p>Synchronous truncate(2).
</p>
<h2>fs.chown(path, uid, gid, callback)<span><a class="mark" href="#all_fs_chown_path_uid_gid_callback" id="all_fs_chown_path_uid_gid_callback">#</a></span></h2>
<p>Asynchronous chown(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.chownSync(path, uid, gid)<span><a class="mark" href="#all_fs_chownsync_path_uid_gid" id="all_fs_chownsync_path_uid_gid">#</a></span></h2>
<p>Synchronous chown(2).
</p>
<h2>fs.fchown(fd, uid, gid, callback)<span><a class="mark" href="#all_fs_fchown_fd_uid_gid_callback" id="all_fs_fchown_fd_uid_gid_callback">#</a></span></h2>
<p>Asynchronous fchown(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.fchownSync(fd, uid, gid)<span><a class="mark" href="#all_fs_fchownsync_fd_uid_gid" id="all_fs_fchownsync_fd_uid_gid">#</a></span></h2>
<p>Synchronous fchown(2).
</p>
<h2>fs.lchown(path, uid, gid, callback)<span><a class="mark" href="#all_fs_lchown_path_uid_gid_callback" id="all_fs_lchown_path_uid_gid_callback">#</a></span></h2>
<p>Asynchronous lchown(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.lchownSync(path, uid, gid)<span><a class="mark" href="#all_fs_lchownsync_path_uid_gid" id="all_fs_lchownsync_path_uid_gid">#</a></span></h2>
<p>Synchronous lchown(2).
</p>
<h2>fs.chmod(path, mode, callback)<span><a class="mark" href="#all_fs_chmod_path_mode_callback" id="all_fs_chmod_path_mode_callback">#</a></span></h2>
<p>Asynchronous chmod(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.chmodSync(path, mode)<span><a class="mark" href="#all_fs_chmodsync_path_mode" id="all_fs_chmodsync_path_mode">#</a></span></h2>
<p>Synchronous chmod(2).
</p>
<h2>fs.fchmod(fd, mode, callback)<span><a class="mark" href="#all_fs_fchmod_fd_mode_callback" id="all_fs_fchmod_fd_mode_callback">#</a></span></h2>
<p>Asynchronous fchmod(2). No arguments other than a possible exception
are given to the completion callback.
</p>
<h2>fs.fchmodSync(fd, mode)<span><a class="mark" href="#all_fs_fchmodsync_fd_mode" id="all_fs_fchmodsync_fd_mode">#</a></span></h2>
<p>Synchronous fchmod(2).
</p>
<h2>fs.lchmod(path, mode, callback)<span><a class="mark" href="#all_fs_lchmod_path_mode_callback" id="all_fs_lchmod_path_mode_callback">#</a></span></h2>
<p>Asynchronous lchmod(2). No arguments other than a possible exception
are given to the completion callback.
</p>
<p>Only available on Mac OS X.
</p>
<h2>fs.lchmodSync(path, mode)<span><a class="mark" href="#all_fs_lchmodsync_path_mode" id="all_fs_lchmodsync_path_mode">#</a></span></h2>
<p>Synchronous lchmod(2).
</p>
<h2>fs.stat(path, callback)<span><a class="mark" href="#all_fs_stat_path_callback" id="all_fs_stat_path_callback">#</a></span></h2>
<p>Asynchronous stat(2). The callback gets two arguments <code>(err, stats)</code> where
<code>stats</code> is a <a href="#fs_class_fs_stats">fs.Stats</a> object. See the <a href="#fs_class_fs_stats">fs.Stats</a>
section below for more information.
</p>
<h2>fs.lstat(path, callback)<span><a class="mark" href="#all_fs_lstat_path_callback" id="all_fs_lstat_path_callback">#</a></span></h2>
<p>Asynchronous lstat(2). The callback gets two arguments <code>(err, stats)</code> where
<code>stats</code> is a <code>fs.Stats</code> object. <code>lstat()</code> is identical to <code>stat()</code>, except that if
<code>path</code> is a symbolic link, then the link itself is stat-ed, not the file that it
refers to.
</p>
<h2>fs.fstat(fd, callback)<span><a class="mark" href="#all_fs_fstat_fd_callback" id="all_fs_fstat_fd_callback">#</a></span></h2>
<p>Asynchronous fstat(2). The callback gets two arguments <code>(err, stats)</code> where
<code>stats</code> is a <code>fs.Stats</code> object. <code>fstat()</code> is identical to <code>stat()</code>, except that
the file to be stat-ed is specified by the file descriptor <code>fd</code>.
</p>
<h2>fs.statSync(path)<span><a class="mark" href="#all_fs_statsync_path" id="all_fs_statsync_path">#</a></span></h2>
<p>Synchronous stat(2). Returns an instance of <code>fs.Stats</code>.
</p>
<h2>fs.lstatSync(path)<span><a class="mark" href="#all_fs_lstatsync_path" id="all_fs_lstatsync_path">#</a></span></h2>
<p>Synchronous lstat(2). Returns an instance of <code>fs.Stats</code>.
</p>
<h2>fs.fstatSync(fd)<span><a class="mark" href="#all_fs_fstatsync_fd" id="all_fs_fstatsync_fd">#</a></span></h2>
<p>Synchronous fstat(2). Returns an instance of <code>fs.Stats</code>.
</p>
<h2>fs.link(srcpath, dstpath, callback)<span><a class="mark" href="#all_fs_link_srcpath_dstpath_callback" id="all_fs_link_srcpath_dstpath_callback">#</a></span></h2>
<p>Asynchronous link(2). No arguments other than a possible exception are given to
the completion callback.
</p>
<h2>fs.linkSync(srcpath, dstpath)<span><a class="mark" href="#all_fs_linksync_srcpath_dstpath" id="all_fs_linksync_srcpath_dstpath">#</a></span></h2>
<p>Synchronous link(2).
</p>
<h2>fs.symlink(srcpath, dstpath, [type], callback)<span><a class="mark" href="#all_fs_symlink_srcpath_dstpath_type_callback" id="all_fs_symlink_srcpath_dstpath_type_callback">#</a></span></h2>
<p>Asynchronous symlink(2). No arguments other than a possible exception are given
to the completion callback.
The <code>type</code> argument can be set to <code>&#39;dir&#39;</code>, <code>&#39;file&#39;</code>, or <code>&#39;junction&#39;</code> (default
is <code>&#39;file&#39;</code>) and is only available on Windows (ignored on other platforms).
Note that Windows junction points require the destination path to be absolute. When using
<code>&#39;junction&#39;</code>, the <code>destination</code> argument will automatically be normalized to absolute path.
</p>
<h2>fs.symlinkSync(srcpath, dstpath, [type])<span><a class="mark" href="#all_fs_symlinksync_srcpath_dstpath_type" id="all_fs_symlinksync_srcpath_dstpath_type">#</a></span></h2>
<p>Synchronous symlink(2).
</p>
<h2>fs.readlink(path, callback)<span><a class="mark" href="#all_fs_readlink_path_callback" id="all_fs_readlink_path_callback">#</a></span></h2>
<p>Asynchronous readlink(2). The callback gets two arguments <code>(err,
linkString)</code>.
</p>
<h2>fs.readlinkSync(path)<span><a class="mark" href="#all_fs_readlinksync_path" id="all_fs_readlinksync_path">#</a></span></h2>
<p>Synchronous readlink(2). Returns the symbolic link&#39;s string value.
</p>
<h2>fs.realpath(path, [cache], callback)<span><a class="mark" href="#all_fs_realpath_path_cache_callback" id="all_fs_realpath_path_cache_callback">#</a></span></h2>
<p>Asynchronous realpath(2). The <code>callback</code> gets two arguments <code>(err,
resolvedPath)</code>. May use <code>process.cwd</code> to resolve relative paths. <code>cache</code> is an
object literal of mapped paths that can be used to force a specific path
resolution or avoid additional <code>fs.stat</code> calls for known real paths.
</p>
<p>Example:
</p>
<pre><code>var cache = {&#39;/etc&#39;:&#39;/private/etc&#39;};
fs.realpath(&#39;/etc/passwd&#39;, cache, function (err, resolvedPath) {
if (err) throw err;
console.log(resolvedPath);
});</code></pre>
<h2>fs.realpathSync(path, [cache])<span><a class="mark" href="#all_fs_realpathsync_path_cache" id="all_fs_realpathsync_path_cache">#</a></span></h2>
<p>Synchronous realpath(2). Returns the resolved path.
</p>
<h2>fs.unlink(path, callback)<span><a class="mark" href="#all_fs_unlink_path_callback" id="all_fs_unlink_path_callback">#</a></span></h2>
<p>Asynchronous unlink(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.unlinkSync(path)<span><a class="mark" href="#all_fs_unlinksync_path" id="all_fs_unlinksync_path">#</a></span></h2>
<p>Synchronous unlink(2).
</p>
<h2>fs.rmdir(path, callback)<span><a class="mark" href="#all_fs_rmdir_path_callback" id="all_fs_rmdir_path_callback">#</a></span></h2>
<p>Asynchronous rmdir(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.rmdirSync(path)<span><a class="mark" href="#all_fs_rmdirsync_path" id="all_fs_rmdirsync_path">#</a></span></h2>
<p>Synchronous rmdir(2).
</p>
<h2>fs.mkdir(path, [mode], callback)<span><a class="mark" href="#all_fs_mkdir_path_mode_callback" id="all_fs_mkdir_path_mode_callback">#</a></span></h2>
<p>Asynchronous mkdir(2). No arguments other than a possible exception are given
to the completion callback. <code>mode</code> defaults to <code>0777</code>.
</p>
<h2>fs.mkdirSync(path, [mode])<span><a class="mark" href="#all_fs_mkdirsync_path_mode" id="all_fs_mkdirsync_path_mode">#</a></span></h2>
<p>Synchronous mkdir(2).
</p>
<h2>fs.readdir(path, callback)<span><a class="mark" href="#all_fs_readdir_path_callback" id="all_fs_readdir_path_callback">#</a></span></h2>
<p>Asynchronous readdir(3). Reads the contents of a directory.
The callback gets two arguments <code>(err, files)</code> where <code>files</code> is an array of
the names of the files in the directory excluding <code>&#39;.&#39;</code> and <code>&#39;..&#39;</code>.
</p>
<h2>fs.readdirSync(path)<span><a class="mark" href="#all_fs_readdirsync_path" id="all_fs_readdirsync_path">#</a></span></h2>
<p>Synchronous readdir(3). Returns an array of filenames excluding <code>&#39;.&#39;</code> and
<code>&#39;..&#39;</code>.
</p>
<h2>fs.close(fd, callback)<span><a class="mark" href="#all_fs_close_fd_callback" id="all_fs_close_fd_callback">#</a></span></h2>
<p>Asynchronous close(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.closeSync(fd)<span><a class="mark" href="#all_fs_closesync_fd" id="all_fs_closesync_fd">#</a></span></h2>
<p>Synchronous close(2).
</p>
<h2>fs.open(path, flags, [mode], callback)<span><a class="mark" href="#all_fs_open_path_flags_mode_callback" id="all_fs_open_path_flags_mode_callback">#</a></span></h2>
<p>Asynchronous file open. See open(2). <code>flags</code> can be:
</p>
<ul>
<li><p><code>&#39;r&#39;</code> - Open file for reading.
An exception occurs if the file does not exist.</p>
</li>
<li><p><code>&#39;r+&#39;</code> - Open file for reading and writing.
An exception occurs if the file does not exist.</p>
</li>
<li><p><code>&#39;rs&#39;</code> - Open file for reading in synchronous mode. Instructs the operating
system to bypass the local file system cache.</p>
<p>This is primarily useful for opening files on NFS mounts as it allows you to
skip the potentially stale local cache. It has a very real impact on I/O
performance so don&#39;t use this flag unless you need it.</p>
<p>Note that this doesn&#39;t turn <code>fs.open()</code> into a synchronous blocking call.
If that&#39;s what you want then you should be using <code>fs.openSync()</code></p>
</li>
<li><p><code>&#39;rs+&#39;</code> - Open file for reading and writing, telling the OS to open it
synchronously. See notes for <code>&#39;rs&#39;</code> about using this with caution.</p>
</li>
<li><p><code>&#39;w&#39;</code> - Open file for writing.
The file is created (if it does not exist) or truncated (if it exists).</p>
</li>
<li><p><code>&#39;wx&#39;</code> - Like <code>&#39;w&#39;</code> but fails if <code>path</code> exists.</p>
</li>
<li><p><code>&#39;w+&#39;</code> - Open file for reading and writing.
The file is created (if it does not exist) or truncated (if it exists).</p>
</li>
<li><p><code>&#39;wx+&#39;</code> - Like <code>&#39;w+&#39;</code> but fails if <code>path</code> exists.</p>
</li>
<li><p><code>&#39;a&#39;</code> - Open file for appending.
The file is created if it does not exist.</p>
</li>
<li><p><code>&#39;ax&#39;</code> - Like <code>&#39;a&#39;</code> but fails if <code>path</code> exists.</p>
</li>
<li><p><code>&#39;a+&#39;</code> - Open file for reading and appending.
The file is created if it does not exist.</p>
</li>
<li><p><code>&#39;ax+&#39;</code> - Like <code>&#39;a+&#39;</code> but fails if <code>path</code> exists.</p>
</li>
</ul>
<p><code>mode</code> sets the file mode (permission and sticky bits), but only if the file was
created. It defaults to <code>0666</code>, readable and writeable.
</p>
<p>The callback gets two arguments <code>(err, fd)</code>.
</p>
<p>The exclusive flag <code>&#39;x&#39;</code> (<code>O_EXCL</code> flag in open(2)) ensures that <code>path</code> is newly
created. On POSIX systems, <code>path</code> is considered to exist even if it is a symlink
to a non-existent file. The exclusive flag may or may not work with network file
systems.
</p>
<p>On Linux, positional writes don&#39;t work when the file is opened in append mode.
The kernel ignores the position argument and always appends the data to
the end of the file.
</p>
<h2>fs.openSync(path, flags, [mode])<span><a class="mark" href="#all_fs_opensync_path_flags_mode" id="all_fs_opensync_path_flags_mode">#</a></span></h2>
<p>Synchronous version of <code>fs.open()</code>.
</p>
<h2>fs.utimes(path, atime, mtime, callback)<span><a class="mark" href="#all_fs_utimes_path_atime_mtime_callback" id="all_fs_utimes_path_atime_mtime_callback">#</a></span></h2>
<h2>fs.utimesSync(path, atime, mtime)<span><a class="mark" href="#all_fs_utimessync_path_atime_mtime" id="all_fs_utimessync_path_atime_mtime">#</a></span></h2>
<p>Change file timestamps of the file referenced by the supplied path.
</p>
<h2>fs.futimes(fd, atime, mtime, callback)<span><a class="mark" href="#all_fs_futimes_fd_atime_mtime_callback" id="all_fs_futimes_fd_atime_mtime_callback">#</a></span></h2>
<h2>fs.futimesSync(fd, atime, mtime)<span><a class="mark" href="#all_fs_futimessync_fd_atime_mtime" id="all_fs_futimessync_fd_atime_mtime">#</a></span></h2>
<p>Change the file timestamps of a file referenced by the supplied file
descriptor.
</p>
<h2>fs.fsync(fd, callback)<span><a class="mark" href="#all_fs_fsync_fd_callback" id="all_fs_fsync_fd_callback">#</a></span></h2>
<p>Asynchronous fsync(2). No arguments other than a possible exception are given
to the completion callback.
</p>
<h2>fs.fsyncSync(fd)<span><a class="mark" href="#all_fs_fsyncsync_fd" id="all_fs_fsyncsync_fd">#</a></span></h2>
<p>Synchronous fsync(2).
</p>
<h2>fs.write(fd, buffer, offset, length, position, callback)<span><a class="mark" href="#all_fs_write_fd_buffer_offset_length_position_callback" id="all_fs_write_fd_buffer_offset_length_position_callback">#</a></span></h2>
<p>Write <code>buffer</code> to the file specified by <code>fd</code>.
</p>
<p><code>offset</code> and <code>length</code> determine the part of the buffer to be written.
</p>
<p><code>position</code> refers to the offset from the beginning of the file where this data
should be written. If <code>position</code> is <code>null</code>, the data will be written at the
current position.
See pwrite(2).
</p>
<p>The callback will be given three arguments <code>(err, written, buffer)</code> where <code>written</code>
specifies how many <em>bytes</em> were written from <code>buffer</code>.
</p>
<p>Note that it is unsafe to use <code>fs.write</code> multiple times on the same file
without waiting for the callback. For this scenario,
<code>fs.createWriteStream</code> is strongly recommended.
</p>
<p>On Linux, positional writes don&#39;t work when the file is opened in append mode.
The kernel ignores the position argument and always appends the data to
the end of the file.
</p>
<h2>fs.writeSync(fd, buffer, offset, length, position)<span><a class="mark" href="#all_fs_writesync_fd_buffer_offset_length_position" id="all_fs_writesync_fd_buffer_offset_length_position">#</a></span></h2>
<p>Synchronous version of <code>fs.write()</code>. Returns the number of bytes written.
</p>
<h2>fs.read(fd, buffer, offset, length, position, callback)<span><a class="mark" href="#all_fs_read_fd_buffer_offset_length_position_callback" id="all_fs_read_fd_buffer_offset_length_position_callback">#</a></span></h2>
<p>Read data from the file specified by <code>fd</code>.
</p>
<p><code>buffer</code> is the buffer that the data will be written to.
</p>
<p><code>offset</code> is the offset in the buffer to start writing at.
</p>
<p><code>length</code> is an integer specifying the number of bytes to read.
</p>
<p><code>position</code> is an integer specifying where to begin reading from in the file.
If <code>position</code> is <code>null</code>, data will be read from the current file position.
</p>
<p>The callback is given the three arguments, <code>(err, bytesRead, buffer)</code>.
</p>
<h2>fs.readSync(fd, buffer, offset, length, position)<span><a class="mark" href="#all_fs_readsync_fd_buffer_offset_length_position" id="all_fs_readsync_fd_buffer_offset_length_position">#</a></span></h2>
<p>Synchronous version of <code>fs.read</code>. Returns the number of <code>bytesRead</code>.
</p>
<h2>fs.readFile(filename, [options], callback)<span><a class="mark" href="#all_fs_readfile_filename_options_callback" id="all_fs_readfile_filename_options_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>filename</code> <span class="type">String</span></li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>encoding</code> <span class="type">String | Null</span> default = <code>null</code></li>
<li><code>flag</code> <span class="type">String</span> default = <code>&#39;r&#39;</code></li>
</ul>
</li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>Asynchronously reads the entire contents of a file. Example:
</p>
<pre><code>fs.readFile(&#39;/etc/passwd&#39;, function (err, data) {
if (err) throw err;
console.log(data);
});</code></pre>
<p>The callback is passed two arguments <code>(err, data)</code>, where <code>data</code> is the
contents of the file.
</p>
<p>If no encoding is specified, then the raw buffer is returned.
</p>
<h2>fs.readFileSync(filename, [options])<span><a class="mark" href="#all_fs_readfilesync_filename_options" id="all_fs_readfilesync_filename_options">#</a></span></h2>
<p>Synchronous version of <code>fs.readFile</code>. Returns the contents of the <code>filename</code>.
</p>
<p>If the <code>encoding</code> option is specified then this function returns a
string. Otherwise it returns a buffer.
</p>
<h2>fs.writeFile(filename, data, [options], callback)<span><a class="mark" href="#all_fs_writefile_filename_data_options_callback" id="all_fs_writefile_filename_data_options_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>filename</code> <span class="type">String</span></li>
<li><code>data</code> <span class="type">String | Buffer</span></li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>encoding</code> <span class="type">String | Null</span> default = <code>&#39;utf8&#39;</code></li>
<li><code>mode</code> <span class="type">Number</span> default = <code>438</code> (aka <code>0666</code> in Octal)</li>
<li><code>flag</code> <span class="type">String</span> default = <code>&#39;w&#39;</code></li>
</ul>
</li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>Asynchronously writes data to a file, replacing the file if it already exists.
<code>data</code> can be a string or a buffer.
</p>
<p>The <code>encoding</code> option is ignored if <code>data</code> is a buffer. It defaults
to <code>&#39;utf8&#39;</code>.
</p>
<p>Example:
</p>
<pre><code>fs.writeFile(&#39;message.txt&#39;, &#39;Hello Node&#39;, function (err) {
if (err) throw err;
console.log(&#39;It\&#39;s saved!&#39;);
});</code></pre>
<h2>fs.writeFileSync(filename, data, [options])<span><a class="mark" href="#all_fs_writefilesync_filename_data_options" id="all_fs_writefilesync_filename_data_options">#</a></span></h2>
<p>The synchronous version of <code>fs.writeFile</code>.
</p>
<h2>fs.appendFile(filename, data, [options], callback)<span><a class="mark" href="#all_fs_appendfile_filename_data_options_callback" id="all_fs_appendfile_filename_data_options_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>filename</code> <span class="type">String</span></li>
<li><code>data</code> <span class="type">String | Buffer</span></li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>encoding</code> <span class="type">String | Null</span> default = <code>&#39;utf8&#39;</code></li>
<li><code>mode</code> <span class="type">Number</span> default = <code>438</code> (aka <code>0666</code> in Octal)</li>
<li><code>flag</code> <span class="type">String</span> default = <code>&#39;a&#39;</code></li>
</ul>
</li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>Asynchronously append data to a file, creating the file if it not yet exists.
<code>data</code> can be a string or a buffer.
</p>
<p>Example:
</p>
<pre><code>fs.appendFile(&#39;message.txt&#39;, &#39;data to append&#39;, function (err) {
if (err) throw err;
console.log(&#39;The &quot;data to append&quot; was appended to file!&#39;);
});</code></pre>
<h2>fs.appendFileSync(filename, data, [options])<span><a class="mark" href="#all_fs_appendfilesync_filename_data_options" id="all_fs_appendfilesync_filename_data_options">#</a></span></h2>
<p>The synchronous version of <code>fs.appendFile</code>.
</p>
<h2>fs.watchFile(filename, [options], listener)<span><a class="mark" href="#all_fs_watchfile_filename_options_listener" id="all_fs_watchfile_filename_options_listener">#</a></span></h2>
<pre class="api_stability_2">Stability: 2 - Unstable. Use fs.watch instead, if possible.</pre><p>Watch for changes on <code>filename</code>. The callback <code>listener</code> will be called each
time the file is accessed.
</p>
<p>The second argument is optional. The <code>options</code> if provided should be an object
containing two members a boolean, <code>persistent</code>, and <code>interval</code>. <code>persistent</code>
indicates whether the process should continue to run as long as files are
being watched. <code>interval</code> indicates how often the target should be polled,
in milliseconds. The default is <code>{ persistent: true, interval: 5007 }</code>.
</p>
<p>The <code>listener</code> gets two arguments the current stat object and the previous
stat object:
</p>
<pre><code>fs.watchFile(&#39;message.text&#39;, function (curr, prev) {
console.log(&#39;the current mtime is: &#39; + curr.mtime);
console.log(&#39;the previous mtime was: &#39; + prev.mtime);
});</code></pre>
<p>These stat objects are instances of <code>fs.Stat</code>.
</p>
<p>If you want to be notified when the file was modified, not just accessed
you need to compare <code>curr.mtime</code> and <code>prev.mtime</code>.
</p>
<h2>fs.unwatchFile(filename, [listener])<span><a class="mark" href="#all_fs_unwatchfile_filename_listener" id="all_fs_unwatchfile_filename_listener">#</a></span></h2>
<pre class="api_stability_2">Stability: 2 - Unstable. Use fs.watch instead, if possible.</pre><p>Stop watching for changes on <code>filename</code>. If <code>listener</code> is specified, only that
particular listener is removed. Otherwise, <em>all</em> listeners are removed and you
have effectively stopped watching <code>filename</code>.
</p>
<p>Calling <code>fs.unwatchFile()</code> with a filename that is not being watched is a
no-op, not an error.
</p>
<h2>fs.watch(filename, [options], [listener])<span><a class="mark" href="#all_fs_watch_filename_options_listener" id="all_fs_watch_filename_options_listener">#</a></span></h2>
<pre class="api_stability_2">Stability: 2 - Unstable.</pre><p>Watch for changes on <code>filename</code>, where <code>filename</code> is either a file or a
directory. The returned object is a <a href="#fs_class_fs_fswatcher">fs.FSWatcher</a>.
</p>
<p>The second argument is optional. The <code>options</code> if provided should be an object
containing a boolean member <code>persistent</code>, which indicates whether the process
should continue to run as long as files are being watched. The default is
<code>{ persistent: true }</code>.
</p>
<p>The listener callback gets two arguments <code>(event, filename)</code>. <code>event</code> is either
&#39;rename&#39; or &#39;change&#39;, and <code>filename</code> is the name of the file which triggered
the event.
</p>
<h3>Caveats<span><a class="mark" href="#all_caveats" id="all_caveats">#</a></span></h3>
<!--type=misc-->
<p>The <code>fs.watch</code> API is not 100% consistent across platforms, and is
unavailable in some situations.
</p>
<h4>Availability<span><a class="mark" href="#all_availability" id="all_availability">#</a></span></h4>
<!--type=misc-->
<p>This feature depends on the underlying operating system providing a way
to be notified of filesystem changes.
</p>
<ul>
<li>On Linux systems, this uses <code>inotify</code>.</li>
<li>On BSD systems (including OS X), this uses <code>kqueue</code>.</li>
<li>On SunOS systems (including Solaris and SmartOS), this uses <code>event ports</code>.</li>
<li>On Windows systems, this feature depends on <code>ReadDirectoryChangesW</code>.</li>
</ul>
<p>If the underlying functionality is not available for some reason, then
<code>fs.watch</code> will not be able to function. For example, watching files or
directories on network file systems (NFS, SMB, etc.) often doesn&#39;t work
reliably or at all.
</p>
<p>You can still use <code>fs.watchFile</code>, which uses stat polling, but it is slower and
less reliable.
</p>
<h4>Filename Argument<span><a class="mark" href="#all_filename_argument" id="all_filename_argument">#</a></span></h4>
<!--type=misc-->
<p>Providing <code>filename</code> argument in the callback is not supported
on every platform (currently it&#39;s only supported on Linux and Windows). Even
on supported platforms <code>filename</code> is not always guaranteed to be provided.
Therefore, don&#39;t assume that <code>filename</code> argument is always provided in the
callback, and have some fallback logic if it is null.
</p>
<pre><code>fs.watch(&#39;somedir&#39;, function (event, filename) {
console.log(&#39;event is: &#39; + event);
if (filename) {
console.log(&#39;filename provided: &#39; + filename);
} else {
console.log(&#39;filename not provided&#39;);
}
});</code></pre>
<h2>fs.exists(path, callback)<span><a class="mark" href="#all_fs_exists_path_callback" id="all_fs_exists_path_callback">#</a></span></h2>
<p>Test whether or not the given path exists by checking with the file system.
Then call the <code>callback</code> argument with either true or false. Example:
</p>
<pre><code>fs.exists(&#39;/etc/passwd&#39;, function (exists) {
util.debug(exists ? &quot;it&#39;s there&quot; : &quot;no passwd!&quot;);
});</code></pre>
<p><code>fs.exists()</code> is an anachronism and exists only for historical reasons.
There should almost never be a reason to use it in your own code.
</p>
<p>In particular, checking if a file exists before opening it is an anti-pattern
that leaves you vulnerable to race conditions: another process may remove the
file between the calls to <code>fs.exists()</code> and <code>fs.open()</code>. Just open the file
and handle the error when it&#39;s not there.
</p>
<h2>fs.existsSync(path)<span><a class="mark" href="#all_fs_existssync_path" id="all_fs_existssync_path">#</a></span></h2>
<p>Synchronous version of <code>fs.exists</code>.
</p>
<h2>Class: fs.Stats<span><a class="mark" href="#all_class_fs_stats" id="all_class_fs_stats">#</a></span></h2>
<p>Objects returned from <code>fs.stat()</code>, <code>fs.lstat()</code> and <code>fs.fstat()</code> and their
synchronous counterparts are of this type.
</p>
<ul>
<li><code>stats.isFile()</code></li>
<li><code>stats.isDirectory()</code></li>
<li><code>stats.isBlockDevice()</code></li>
<li><code>stats.isCharacterDevice()</code></li>
<li><code>stats.isSymbolicLink()</code> (only valid with <code>fs.lstat()</code>)</li>
<li><code>stats.isFIFO()</code></li>
<li><code>stats.isSocket()</code></li>
</ul>
<p>For a regular file <code>util.inspect(stats)</code> would return a string very
similar to this:
</p>
<pre><code>{ dev: 2114,
ino: 48064969,
mode: 33188,
nlink: 1,
uid: 85,
gid: 100,
rdev: 0,
size: 527,
blksize: 4096,
blocks: 8,
atime: Mon, 10 Oct 2011 23:24:11 GMT,
mtime: Mon, 10 Oct 2011 23:24:11 GMT,
ctime: Mon, 10 Oct 2011 23:24:11 GMT }</code></pre>
<p>Please note that <code>atime</code>, <code>mtime</code> and <code>ctime</code> are instances
of <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date">Date</a> object and to compare the values of
these objects you should use appropriate methods. For most
general uses <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/getTime">getTime()</a> will return
the number of milliseconds elapsed since <em>1 January 1970
00:00:00 UTC</em> and this integer should be sufficient for
any comparison, however there additional methods which can
be used for displaying fuzzy information. More details can
be found in the <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date">MDN JavaScript Reference</a> page.
</p>
<h2>fs.createReadStream(path, [options])<span><a class="mark" href="#all_fs_createreadstream_path_options" id="all_fs_createreadstream_path_options">#</a></span></h2>
<p>Returns a new ReadStream object (See <code>Readable Stream</code>).
</p>
<p><code>options</code> is an object with the following defaults:
</p>
<pre><code>{ flags: &#39;r&#39;,
encoding: null,
fd: null,
mode: 0666,
autoClose: true
}</code></pre>
<p><code>options</code> can include <code>start</code> and <code>end</code> values to read a range of bytes from
the file instead of the entire file. Both <code>start</code> and <code>end</code> are inclusive and
start at 0. The <code>encoding</code> can be <code>&#39;utf8&#39;</code>, <code>&#39;ascii&#39;</code>, or <code>&#39;base64&#39;</code>.
</p>
<p>If <code>autoClose</code> is false, then the file descriptor won&#39;t be closed, even if
there&#39;s an error. It is your responsiblity to close it and make sure
there&#39;s no file descriptor leak. If <code>autoClose</code> is set to true (default
behavior), on <code>error</code> or <code>end</code> the file descriptor will be closed
automatically.
</p>
<p>An example to read the last 10 bytes of a file which is 100 bytes long:
</p>
<pre><code>fs.createReadStream(&#39;sample.txt&#39;, {start: 90, end: 99});</code></pre>
<h2>Class: fs.ReadStream<span><a class="mark" href="#all_class_fs_readstream" id="all_class_fs_readstream">#</a></span></h2>
<p><code>ReadStream</code> is a <a href="stream.html#stream_class_stream_readable">Readable Stream</a>.
</p>
<h3>Event: &#39;open&#39;<span><a class="mark" href="#all_event_open" id="all_event_open">#</a></span></h3>
<div class="signature"><ul>
<li><code>fd</code> <span class="type">Integer</span> file descriptor used by the ReadStream.</li>
</div></ul>
<p>Emitted when the ReadStream&#39;s file is opened.
</p>
<h2>fs.createWriteStream(path, [options])<span><a class="mark" href="#all_fs_createwritestream_path_options" id="all_fs_createwritestream_path_options">#</a></span></h2>
<p>Returns a new WriteStream object (See <code>Writable Stream</code>).
</p>
<p><code>options</code> is an object with the following defaults:
</p>
<pre><code>{ flags: &#39;w&#39;,
encoding: null,
mode: 0666 }</code></pre>
<p><code>options</code> may also include a <code>start</code> option to allow writing data at
some position past the beginning of the file. Modifying a file rather
than replacing it may require a <code>flags</code> mode of <code>r+</code> rather than the
default mode <code>w</code>.
</p>
<h2>Class: fs.WriteStream<span><a class="mark" href="#all_class_fs_writestream" id="all_class_fs_writestream">#</a></span></h2>
<p><code>WriteStream</code> is a <a href="stream.html#stream_class_stream_writable">Writable Stream</a>.
</p>
<h3>Event: &#39;open&#39;<span><a class="mark" href="#all_event_open_1" id="all_event_open_1">#</a></span></h3>
<div class="signature"><ul>
<li><code>fd</code> <span class="type">Integer</span> file descriptor used by the WriteStream.</li>
</div></ul>
<p>Emitted when the WriteStream&#39;s file is opened.
</p>
<h3>file.bytesWritten<span><a class="mark" href="#all_file_byteswritten" id="all_file_byteswritten">#</a></span></h3>
<p>The number of bytes written so far. Does not include data that is still queued
for writing.
</p>
<h2>Class: fs.FSWatcher<span><a class="mark" href="#all_class_fs_fswatcher" id="all_class_fs_fswatcher">#</a></span></h2>
<p>Objects returned from <code>fs.watch()</code> are of this type.
</p>
<h3>watcher.close()<span><a class="mark" href="#all_watcher_close" id="all_watcher_close">#</a></span></h3>
<p>Stop watching for changes on the given <code>fs.FSWatcher</code>.
</p>
<h3>Event: &#39;change&#39;<span><a class="mark" href="#all_event_change" id="all_event_change">#</a></span></h3>
<div class="signature"><ul>
<li><code>event</code> <span class="type">String</span> The type of fs change</li>
<li><code>filename</code> <span class="type">String</span> The filename that changed (if relevant/available)</li>
</div></ul>
<p>Emitted when something changes in a watched directory or file.
See more details in <a href="#fs_fs_watch_filename_options_listener">fs.watch</a>.
</p>
<h3>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_2" id="all_event_error_2">#</a></span></h3>
<div class="signature"><ul>
<li><code>error</code> <span class="type">Error object</span></li>
</div></ul>
<p>Emitted when an error occurs.
</p>
<h1>Path<span><a class="mark" href="#all_path" id="all_path">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>This module contains utilities for handling and transforming file
paths. Almost all these methods perform only string transformations.
The file system is not consulted to check whether paths are valid.
</p>
<p>Use <code>require(&#39;path&#39;)</code> to use this module. The following methods are provided:
</p>
<h2>path.normalize(p)<span><a class="mark" href="#all_path_normalize_p" id="all_path_normalize_p">#</a></span></h2>
<p>Normalize a string path, taking care of <code>&#39;..&#39;</code> and <code>&#39;.&#39;</code> parts.
</p>
<p>When multiple slashes are found, they&#39;re replaced by a single one;
when the path contains a trailing slash, it is preserved.
On Windows backslashes are used.
</p>
<p>Example:
</p>
<pre><code>path.normalize(&#39;/foo/bar//baz/asdf/quux/..&#39;)
// returns
&#39;/foo/bar/baz/asdf&#39;</code></pre>
<h2>path.join([path1], [path2], [...])<span><a class="mark" href="#all_path_join_path1_path2" id="all_path_join_path1_path2">#</a></span></h2>
<p>Join all arguments together and normalize the resulting path.
</p>
<p>Arguments must be strings. In v0.8, non-string arguments were
silently ignored. In v0.10 and up, an exception is thrown.
</p>
<p>Example:
</p>
<pre><code>path.join(&#39;/foo&#39;, &#39;bar&#39;, &#39;baz/asdf&#39;, &#39;quux&#39;, &#39;..&#39;)
// returns
&#39;/foo/bar/baz/asdf&#39;
path.join(&#39;foo&#39;, {}, &#39;bar&#39;)
// throws exception
TypeError: Arguments to path.join must be strings</code></pre>
<h2>path.resolve([from ...], to)<span><a class="mark" href="#all_path_resolve_from_to" id="all_path_resolve_from_to">#</a></span></h2>
<p>Resolves <code>to</code> to an absolute path.
</p>
<p>If <code>to</code> isn&#39;t already absolute <code>from</code> arguments are prepended in right to left
order, until an absolute path is found. If after using all <code>from</code> paths still
no absolute path is found, the current working directory is used as well. The
resulting path is normalized, and trailing slashes are removed unless the path
gets resolved to the root directory. Non-string arguments are ignored.
</p>
<p>Another way to think of it is as a sequence of <code>cd</code> commands in a shell.
</p>
<pre><code>path.resolve(&#39;foo/bar&#39;, &#39;/tmp/file/&#39;, &#39;..&#39;, &#39;a/../subfile&#39;)</code></pre>
<p>Is similar to:
</p>
<pre><code>cd foo/bar
cd /tmp/file/
cd ..
cd a/../subfile
pwd</code></pre>
<p>The difference is that the different paths don&#39;t need to exist and may also be
files.
</p>
<p>Examples:
</p>
<pre><code>path.resolve(&#39;/foo/bar&#39;, &#39;./baz&#39;)
// returns
&#39;/foo/bar/baz&#39;
path.resolve(&#39;/foo/bar&#39;, &#39;/tmp/file/&#39;)
// returns
&#39;/tmp/file&#39;
path.resolve(&#39;wwwroot&#39;, &#39;static_files/png/&#39;, &#39;../gif/image.gif&#39;)
// if currently in /home/myself/node, it returns
&#39;/home/myself/node/wwwroot/static_files/gif/image.gif&#39;</code></pre>
<h2>path.relative(from, to)<span><a class="mark" href="#all_path_relative_from_to" id="all_path_relative_from_to">#</a></span></h2>
<p>Solve the relative path from <code>from</code> to <code>to</code>.
</p>
<p>At times we have two absolute paths, and we need to derive the relative
path from one to the other. This is actually the reverse transform of
<code>path.resolve</code>, which means we see that:
</p>
<pre><code>path.resolve(from, path.relative(from, to)) == path.resolve(to)</code></pre>
<p>Examples:
</p>
<pre><code>path.relative(&#39;C:\\orandea\\test\\aaa&#39;, &#39;C:\\orandea\\impl\\bbb&#39;)
// returns
&#39;..\\..\\impl\\bbb&#39;
path.relative(&#39;/data/orandea/test/aaa&#39;, &#39;/data/orandea/impl/bbb&#39;)
// returns
&#39;../../impl/bbb&#39;</code></pre>
<h2>path.dirname(p)<span><a class="mark" href="#all_path_dirname_p" id="all_path_dirname_p">#</a></span></h2>
<p>Return the directory name of a path. Similar to the Unix <code>dirname</code> command.
</p>
<p>Example:
</p>
<pre><code>path.dirname(&#39;/foo/bar/baz/asdf/quux&#39;)
// returns
&#39;/foo/bar/baz/asdf&#39;</code></pre>
<h2>path.basename(p, [ext])<span><a class="mark" href="#all_path_basename_p_ext" id="all_path_basename_p_ext">#</a></span></h2>
<p>Return the last portion of a path. Similar to the Unix <code>basename</code> command.
</p>
<p>Example:
</p>
<pre><code>path.basename(&#39;/foo/bar/baz/asdf/quux.html&#39;)
// returns
&#39;quux.html&#39;
path.basename(&#39;/foo/bar/baz/asdf/quux.html&#39;, &#39;.html&#39;)
// returns
&#39;quux&#39;</code></pre>
<h2>path.extname(p)<span><a class="mark" href="#all_path_extname_p" id="all_path_extname_p">#</a></span></h2>
<p>Return the extension of the path, from the last &#39;.&#39; to end of string
in the last portion of the path. If there is no &#39;.&#39; in the last portion
of the path or the first character of it is &#39;.&#39;, then it returns
an empty string. Examples:
</p>
<pre><code>path.extname(&#39;index.html&#39;)
// returns
&#39;.html&#39;
path.extname(&#39;index.&#39;)
// returns
&#39;.&#39;
path.extname(&#39;index&#39;)
// returns
&#39;&#39;</code></pre>
<h2>path.sep<span><a class="mark" href="#all_path_sep" id="all_path_sep">#</a></span></h2>
<p>The platform-specific file separator. <code>&#39;\\&#39;</code> or <code>&#39;/&#39;</code>.
</p>
<p>An example on *nix:
</p>
<pre><code>&#39;foo/bar/baz&#39;.split(path.sep)
// returns
[&#39;foo&#39;, &#39;bar&#39;, &#39;baz&#39;]</code></pre>
<p>An example on Windows:
</p>
<pre><code>&#39;foo\\bar\\baz&#39;.split(path.sep)
// returns
[&#39;foo&#39;, &#39;bar&#39;, &#39;baz&#39;]</code></pre>
<h2>path.delimiter<span><a class="mark" href="#all_path_delimiter" id="all_path_delimiter">#</a></span></h2>
<p>The platform-specific path delimiter, <code>;</code> or <code>&#39;:&#39;</code>.
</p>
<p>An example on *nix:
</p>
<pre><code>console.log(process.env.PATH)
// &#39;/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin&#39;
process.env.PATH.split(path.delimiter)
// returns
[&#39;/usr/bin&#39;, &#39;/bin&#39;, &#39;/usr/sbin&#39;, &#39;/sbin&#39;, &#39;/usr/local/bin&#39;]</code></pre>
<p>An example on Windows:
</p>
<pre><code>console.log(process.env.PATH)
// &#39;C:\Windows\system32;C:\Windows;C:\Program Files\nodejs\&#39;
process.env.PATH.split(path.delimiter)
// returns
[&#39;C:\Windows\system32&#39;, &#39;C:\Windows&#39;, &#39;C:\Program Files\nodejs\&#39;]</code></pre>
<h1>net<span><a class="mark" href="#all_net" id="all_net">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>The <code>net</code> module provides you with an asynchronous network wrapper. It contains
methods for creating both servers and clients (called streams). You can include
this module with <code>require(&#39;net&#39;);</code>
</p>
<h2>net.createServer([options], [connectionListener])<span><a class="mark" href="#all_net_createserver_options_connectionlistener" id="all_net_createserver_options_connectionlistener">#</a></span></h2>
<p>Creates a new TCP server. The <code>connectionListener</code> argument is
automatically set as a listener for the <a href="#net_event_connection">&#39;connection&#39;</a> event.
</p>
<p><code>options</code> is an object with the following defaults:
</p>
<pre><code>{ allowHalfOpen: false
}</code></pre>
<p>If <code>allowHalfOpen</code> is <code>true</code>, then the socket won&#39;t automatically send a FIN
packet when the other end of the socket sends a FIN packet. The socket becomes
non-readable, but still writable. You should call the <code>end()</code> method explicitly.
See <a href="#net_event_end">&#39;end&#39;</a> event for more information.
</p>
<p>Here is an example of an echo server which listens for connections
on port 8124:
</p>
<pre><code>var net = require(&#39;net&#39;);
var server = net.createServer(function(c) { //&#39;connection&#39; listener
console.log(&#39;server connected&#39;);
c.on(&#39;end&#39;, function() {
console.log(&#39;server disconnected&#39;);
});
c.write(&#39;hello\r\n&#39;);
c.pipe(c);
});
server.listen(8124, function() { //&#39;listening&#39; listener
console.log(&#39;server bound&#39;);
});</code></pre>
<p>Test this by using <code>telnet</code>:
</p>
<pre><code>telnet localhost 8124</code></pre>
<p>To listen on the socket <code>/tmp/echo.sock</code> the third line from the last would
just be changed to
</p>
<pre><code>server.listen(&#39;/tmp/echo.sock&#39;, function() { //&#39;listening&#39; listener</code></pre>
<p>Use <code>nc</code> to connect to a UNIX domain socket server:
</p>
<pre><code>nc -U /tmp/echo.sock</code></pre>
<h2>net.connect(options, [connectionListener])<span><a class="mark" href="#all_net_connect_options_connectionlistener" id="all_net_connect_options_connectionlistener">#</a></span></h2>
<h2>net.createConnection(options, [connectionListener])<span><a class="mark" href="#all_net_createconnection_options_connectionlistener" id="all_net_createconnection_options_connectionlistener">#</a></span></h2>
<p>Constructs a new socket object and opens the socket to the given location.
When the socket is established, the <a href="#net_event_connect">&#39;connect&#39;</a> event will be emitted.
</p>
<p>For TCP sockets, <code>options</code> argument should be an object which specifies:
</p>
<ul>
<li><p><code>port</code>: Port the client should connect to (Required).</p>
</li>
<li><p><code>host</code>: Host the client should connect to. Defaults to <code>&#39;localhost&#39;</code>.</p>
</li>
<li><p><code>localAddress</code>: Local interface to bind to for network connections.</p>
</li>
</ul>
<p>For UNIX domain sockets, <code>options</code> argument should be an object which specifies:
</p>
<ul>
<li><code>path</code>: Path the client should connect to (Required).</li>
</ul>
<p>Common options are:
</p>
<ul>
<li><code>allowHalfOpen</code>: if <code>true</code>, the socket won&#39;t automatically send
a FIN packet when the other end of the socket sends a FIN packet.
Defaults to <code>false</code>. See <a href="#net_event_end">&#39;end&#39;</a> event for more information.</li>
</ul>
<p>The <code>connectListener</code> parameter will be added as an listener for the
<a href="#net_event_connect">&#39;connect&#39;</a> event.
</p>
<p>Here is an example of a client of echo server as described previously:
</p>
<pre><code>var net = require(&#39;net&#39;);
var client = net.connect({port: 8124},
function() { //&#39;connect&#39; listener
console.log(&#39;client connected&#39;);
client.write(&#39;world!\r\n&#39;);
});
client.on(&#39;data&#39;, function(data) {
console.log(data.toString());
client.end();
});
client.on(&#39;end&#39;, function() {
console.log(&#39;client disconnected&#39;);
});</code></pre>
<p>To connect on the socket <code>/tmp/echo.sock</code> the second line would just be
changed to
</p>
<pre><code>var client = net.connect({path: &#39;/tmp/echo.sock&#39;});</code></pre>
<h2>net.connect(port, [host], [connectListener])<span><a class="mark" href="#all_net_connect_port_host_connectlistener" id="all_net_connect_port_host_connectlistener">#</a></span></h2>
<h2>net.createConnection(port, [host], [connectListener])<span><a class="mark" href="#all_net_createconnection_port_host_connectlistener" id="all_net_createconnection_port_host_connectlistener">#</a></span></h2>
<p>Creates a TCP connection to <code>port</code> on <code>host</code>. If <code>host</code> is omitted,
<code>&#39;localhost&#39;</code> will be assumed.
The <code>connectListener</code> parameter will be added as an listener for the
<a href="#net_event_connect">&#39;connect&#39;</a> event.
</p>
<h2>net.connect(path, [connectListener])<span><a class="mark" href="#all_net_connect_path_connectlistener" id="all_net_connect_path_connectlistener">#</a></span></h2>
<h2>net.createConnection(path, [connectListener])<span><a class="mark" href="#all_net_createconnection_path_connectlistener" id="all_net_createconnection_path_connectlistener">#</a></span></h2>
<p>Creates unix socket connection to <code>path</code>.
The <code>connectListener</code> parameter will be added as an listener for the
<a href="#net_event_connect">&#39;connect&#39;</a> event.
</p>
<h2>Class: net.Server<span><a class="mark" href="#all_class_net_server" id="all_class_net_server">#</a></span></h2>
<p>This class is used to create a TCP or UNIX server.
</p>
<h3>server.listen(port, [host], [backlog], [callback])<span><a class="mark" href="#all_server_listen_port_host_backlog_callback" id="all_server_listen_port_host_backlog_callback">#</a></span></h3>
<p>Begin accepting connections on the specified <code>port</code> and <code>host</code>. If the
<code>host</code> is omitted, the server will accept connections directed to any
IPv4 address (<code>INADDR_ANY</code>). A port value of zero will assign a random port.
</p>
<p>Backlog is the maximum length of the queue of pending connections.
The actual length will be determined by your OS through sysctl settings such as
<code>tcp_max_syn_backlog</code> and <code>somaxconn</code> on linux. The default value of this
parameter is 511 (not 512).
</p>
<p>This function is asynchronous. When the server has been bound,
<a href="net.html#net_event_listening">&#39;listening&#39;</a> event will be emitted. The last parameter <code>callback</code>
will be added as an listener for the <a href="net.html#net_event_listening">&#39;listening&#39;</a> event.
</p>
<p>One issue some users run into is getting <code>EADDRINUSE</code> errors. This means that
another server is already running on the requested port. One way of handling this
would be to wait a second and then try again. This can be done with
</p>
<pre><code>server.on(&#39;error&#39;, function (e) {
if (e.code == &#39;EADDRINUSE&#39;) {
console.log(&#39;Address in use, retrying...&#39;);
setTimeout(function () {
server.close();
server.listen(PORT, HOST);
}, 1000);
}
});</code></pre>
<p>(Note: All sockets in Node set <code>SO_REUSEADDR</code> already)
</p>
<h3>server.listen(path, [callback])<span><a class="mark" href="#all_server_listen_path_callback" id="all_server_listen_path_callback">#</a></span></h3>
<p>Start a UNIX socket server listening for connections on the given <code>path</code>.
</p>
<p>This function is asynchronous. When the server has been bound,
<a href="net.html#net_event_listening">&#39;listening&#39;</a> event will be emitted. The last parameter <code>callback</code>
will be added as an listener for the <a href="net.html#net_event_listening">&#39;listening&#39;</a> event.
</p>
<h3>server.listen(handle, [callback])<span><a class="mark" href="#all_server_listen_handle_callback" id="all_server_listen_handle_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>handle</code> <span class="type">Object</span></li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>The <code>handle</code> object can be set to either a server or socket (anything
with an underlying <code>_handle</code> member), or a <code>{fd: &lt;n&gt;}</code> object.
</p>
<p>This will cause the server to accept connections on the specified
handle, but it is presumed that the file descriptor or handle has
already been bound to a port or domain socket.
</p>
<p>Listening on a file descriptor is not supported on Windows.
</p>
<p>This function is asynchronous. When the server has been bound,
<a href="#event_listening_">&#39;listening&#39;</a> event will be emitted.
the last parameter <code>callback</code> will be added as an listener for the
<a href="#event_listening_">&#39;listening&#39;</a> event.
</p>
<h3>server.close([callback])<span><a class="mark" href="#all_server_close_callback" id="all_server_close_callback">#</a></span></h3>
<p>Stops the server from accepting new connections and keeps existing
connections. This function is asynchronous, the server is finally
closed when all connections are ended and the server emits a <code>&#39;close&#39;</code>
event. Optionally, you can pass a callback to listen for the <code>&#39;close&#39;</code>
event.
</p>
<h3>server.address()<span><a class="mark" href="#all_server_address_1" id="all_server_address_1">#</a></span></h3>
<p>Returns the bound address, the address family name and port of the server
as reported by the operating system.
Useful to find which port was assigned when giving getting an OS-assigned address.
Returns an object with three properties, e.g.
<code>{ port: 12346, family: &#39;IPv4&#39;, address: &#39;127.0.0.1&#39; }</code>
</p>
<p>Example:
</p>
<pre><code>var server = net.createServer(function (socket) {
socket.end(&quot;goodbye\n&quot;);
});
// grab a random port.
server.listen(function() {
address = server.address();
console.log(&quot;opened server on %j&quot;, address);
});</code></pre>
<p>Don&#39;t call <code>server.address()</code> until the <code>&#39;listening&#39;</code> event has been emitted.
</p>
<h3>server.unref()<span><a class="mark" href="#all_server_unref" id="all_server_unref">#</a></span></h3>
<p>Calling <code>unref</code> on a server will allow the program to exit if this is the only
active server in the event system. If the server is already <code>unref</code>d calling
<code>unref</code> again will have no effect.
</p>
<h3>server.ref()<span><a class="mark" href="#all_server_ref" id="all_server_ref">#</a></span></h3>
<p>Opposite of <code>unref</code>, calling <code>ref</code> on a previously <code>unref</code>d server will <em>not</em>
let the program exit if it&#39;s the only server left (the default behavior). If
the server is <code>ref</code>d calling <code>ref</code> again will have no effect.
</p>
<h3>server.maxConnections<span><a class="mark" href="#all_server_maxconnections_1" id="all_server_maxconnections_1">#</a></span></h3>
<p>Set this property to reject connections when the server&#39;s connection count gets
high.
</p>
<p>It is not recommended to use this option once a socket has been sent to a child
with <code>child_process.fork()</code>.
</p>
<h3>server.connections<span><a class="mark" href="#all_server_connections_1" id="all_server_connections_1">#</a></span></h3>
<p>This function is <strong>deprecated</strong>; please use [server.getConnections()][] instead.
The number of concurrent connections on the server.
</p>
<p>This becomes <code>null</code> when sending a socket to a child with
<code>child_process.fork()</code>. To poll forks and get current number of active
connections use asynchronous <code>server.getConnections</code> instead.
</p>
<p><code>net.Server</code> is an <a href="events.html#events_class_events_eventemitter">EventEmitter</a> with the following events:
</p>
<h3>server.getConnections(callback)<span><a class="mark" href="#all_server_getconnections_callback" id="all_server_getconnections_callback">#</a></span></h3>
<p>Asynchronously get the number of concurrent connections on the server. Works
when sockets were sent to forks.
</p>
<p>Callback should take two arguments <code>err</code> and <code>count</code>.
</p>
<h3>Event: &#39;listening&#39;<span><a class="mark" href="#all_event_listening" id="all_event_listening">#</a></span></h3>
<p>Emitted when the server has been bound after calling <code>server.listen</code>.
</p>
<h3>Event: &#39;connection&#39;<span><a class="mark" href="#all_event_connection" id="all_event_connection">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Socket object</span> The connection object</li>
</div></ul>
<p>Emitted when a new connection is made. <code>socket</code> is an instance of
<code>net.Socket</code>.
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_1" id="all_event_close_1">#</a></span></h3>
<p>Emitted when the server closes. Note that if connections exist, this
event is not emitted until all connections are ended.
</p>
<h3>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_3" id="all_event_error_3">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Error Object</span></li>
</div></ul>
<p>Emitted when an error occurs. The <code>&#39;close&#39;</code> event will be called directly
following this event. See example in discussion of <code>server.listen</code>.
</p>
<h2>Class: net.Socket<span><a class="mark" href="#all_class_net_socket" id="all_class_net_socket">#</a></span></h2>
<p>This object is an abstraction of a TCP or UNIX socket. <code>net.Socket</code>
instances implement a duplex Stream interface. They can be created by the
user and used as a client (with <code>connect()</code>) or they can be created by Node
and passed to the user through the <code>&#39;connection&#39;</code> event of a server.
</p>
<h3>new net.Socket([options])<span><a class="mark" href="#all_new_net_socket_options" id="all_new_net_socket_options">#</a></span></h3>
<p>Construct a new socket object.
</p>
<p><code>options</code> is an object with the following defaults:
</p>
<pre><code>{ fd: null
allowHalfOpen: false,
readable: false,
writable: false
}</code></pre>
<p><code>fd</code> allows you to specify the existing file descriptor of socket.
Set <code>readable</code> and/or <code>writable</code> to <code>true</code> to allow reads and/or writes on this
socket (NOTE: Works only when <code>fd</code> is passed).
About <code>allowHalfOpen</code>, refer to <code>createServer()</code> and <code>&#39;end&#39;</code> event.
</p>
<h3>socket.connect(port, [host], [connectListener])<span><a class="mark" href="#all_socket_connect_port_host_connectlistener" id="all_socket_connect_port_host_connectlistener">#</a></span></h3>
<h3>socket.connect(path, [connectListener])<span><a class="mark" href="#all_socket_connect_path_connectlistener" id="all_socket_connect_path_connectlistener">#</a></span></h3>
<p>Opens the connection for a given socket. If <code>port</code> and <code>host</code> are given,
then the socket will be opened as a TCP socket, if <code>host</code> is omitted,
<code>localhost</code> will be assumed. If a <code>path</code> is given, the socket will be
opened as a unix socket to that path.
</p>
<p>Normally this method is not needed, as <code>net.createConnection</code> opens the
socket. Use this only if you are implementing a custom Socket.
</p>
<p>This function is asynchronous. When the <a href="#net_event_connect">&#39;connect&#39;</a> event is emitted the
socket is established. If there is a problem connecting, the <code>&#39;connect&#39;</code> event
will not be emitted, the <code>&#39;error&#39;</code> event will be emitted with the exception.
</p>
<p>The <code>connectListener</code> parameter will be added as an listener for the
<a href="#net_event_connect">&#39;connect&#39;</a> event.
</p>
<h3>socket.bufferSize<span><a class="mark" href="#all_socket_buffersize" id="all_socket_buffersize">#</a></span></h3>
<p><code>net.Socket</code> has the property that <code>socket.write()</code> always works. This is to
help users get up and running quickly. The computer cannot always keep up
with the amount of data that is written to a socket - the network connection
simply might be too slow. Node will internally queue up the data written to a
socket and send it out over the wire when it is possible. (Internally it is
polling on the socket&#39;s file descriptor for being writable).
</p>
<p>The consequence of this internal buffering is that memory may grow. This
property shows the number of characters currently buffered to be written.
(Number of characters is approximately equal to the number of bytes to be
written, but the buffer may contain strings, and the strings are lazily
encoded, so the exact number of bytes is not known.)
</p>
<p>Users who experience large or growing <code>bufferSize</code> should attempt to
&quot;throttle&quot; the data flows in their program with <code>pause()</code> and <code>resume()</code>.
</p>
<h3>socket.setEncoding([encoding])<span><a class="mark" href="#all_socket_setencoding_encoding" id="all_socket_setencoding_encoding">#</a></span></h3>
<p>Set the encoding for the socket as a Readable Stream. See
<a href="stream.html#stream_stream_setencoding_encoding">stream.setEncoding()</a> for more information.
</p>
<h3>socket.write(data, [encoding], [callback])<span><a class="mark" href="#all_socket_write_data_encoding_callback" id="all_socket_write_data_encoding_callback">#</a></span></h3>
<p>Sends data on the socket. The second parameter specifies the encoding in the
case of a string--it defaults to UTF8 encoding.
</p>
<p>Returns <code>true</code> if the entire data was flushed successfully to the kernel
buffer. Returns <code>false</code> if all or part of the data was queued in user memory.
<code>&#39;drain&#39;</code> will be emitted when the buffer is again free.
</p>
<p>The optional <code>callback</code> parameter will be executed when the data is finally
written out - this may not be immediately.
</p>
<h3>socket.end([data], [encoding])<span><a class="mark" href="#all_socket_end_data_encoding" id="all_socket_end_data_encoding">#</a></span></h3>
<p>Half-closes the socket. i.e., it sends a FIN packet. It is possible the
server will still send some data.
</p>
<p>If <code>data</code> is specified, it is equivalent to calling
<code>socket.write(data, encoding)</code> followed by <code>socket.end()</code>.
</p>
<h3>socket.destroy()<span><a class="mark" href="#all_socket_destroy" id="all_socket_destroy">#</a></span></h3>
<p>Ensures that no more I/O activity happens on this socket. Only necessary in
case of errors (parse error or so).
</p>
<h3>socket.pause()<span><a class="mark" href="#all_socket_pause" id="all_socket_pause">#</a></span></h3>
<p>Pauses the reading of data. That is, <code>&#39;data&#39;</code> events will not be emitted.
Useful to throttle back an upload.
</p>
<h3>socket.resume()<span><a class="mark" href="#all_socket_resume" id="all_socket_resume">#</a></span></h3>
<p>Resumes reading after a call to <code>pause()</code>.
</p>
<h3>socket.setTimeout(timeout, [callback])<span><a class="mark" href="#all_socket_settimeout_timeout_callback" id="all_socket_settimeout_timeout_callback">#</a></span></h3>
<p>Sets the socket to timeout after <code>timeout</code> milliseconds of inactivity on
the socket. By default <code>net.Socket</code> do not have a timeout.
</p>
<p>When an idle timeout is triggered the socket will receive a <code>&#39;timeout&#39;</code>
event but the connection will not be severed. The user must manually <code>end()</code>
or <code>destroy()</code> the socket.
</p>
<p>If <code>timeout</code> is 0, then the existing idle timeout is disabled.
</p>
<p>The optional <code>callback</code> parameter will be added as a one time listener for the
<code>&#39;timeout&#39;</code> event.
</p>
<h3>socket.setNoDelay([noDelay])<span><a class="mark" href="#all_socket_setnodelay_nodelay" id="all_socket_setnodelay_nodelay">#</a></span></h3>
<p>Disables the Nagle algorithm. By default TCP connections use the Nagle
algorithm, they buffer data before sending it off. Setting <code>true</code> for
<code>noDelay</code> will immediately fire off data each time <code>socket.write()</code> is called.
<code>noDelay</code> defaults to <code>true</code>.
</p>
<h3>socket.setKeepAlive([enable], [initialDelay])<span><a class="mark" href="#all_socket_setkeepalive_enable_initialdelay" id="all_socket_setkeepalive_enable_initialdelay">#</a></span></h3>
<p>Enable/disable keep-alive functionality, and optionally set the initial
delay before the first keepalive probe is sent on an idle socket.
<code>enable</code> defaults to <code>false</code>.
</p>
<p>Set <code>initialDelay</code> (in milliseconds) to set the delay between the last
data packet received and the first keepalive probe. Setting 0 for
initialDelay will leave the value unchanged from the default
(or previous) setting. Defaults to <code>0</code>.
</p>
<h3>socket.address()<span><a class="mark" href="#all_socket_address" id="all_socket_address">#</a></span></h3>
<p>Returns the bound address, the address family name and port of the
socket as reported by the operating system. Returns an object with
three properties, e.g.
<code>{ port: 12346, family: &#39;IPv4&#39;, address: &#39;127.0.0.1&#39; }</code>
</p>
<h3>socket.unref()<span><a class="mark" href="#all_socket_unref" id="all_socket_unref">#</a></span></h3>
<p>Calling <code>unref</code> on a socket will allow the program to exit if this is the only
active socket in the event system. If the socket is already <code>unref</code>d calling
<code>unref</code> again will have no effect.
</p>
<h3>socket.ref()<span><a class="mark" href="#all_socket_ref" id="all_socket_ref">#</a></span></h3>
<p>Opposite of <code>unref</code>, calling <code>ref</code> on a previously <code>unref</code>d socket will <em>not</em>
let the program exit if it&#39;s the only socket left (the default behavior). If
the socket is <code>ref</code>d calling <code>ref</code> again will have no effect.
</p>
<h3>socket.remoteAddress<span><a class="mark" href="#all_socket_remoteaddress" id="all_socket_remoteaddress">#</a></span></h3>
<p>The string representation of the remote IP address. For example,
<code>&#39;74.125.127.100&#39;</code> or <code>&#39;2001:4860:a005::68&#39;</code>.
</p>
<h3>socket.remotePort<span><a class="mark" href="#all_socket_remoteport" id="all_socket_remoteport">#</a></span></h3>
<p>The numeric representation of the remote port. For example,
<code>80</code> or <code>21</code>.
</p>
<h3>socket.localAddress<span><a class="mark" href="#all_socket_localaddress" id="all_socket_localaddress">#</a></span></h3>
<p>The string representation of the local IP address the remote client is
connecting on. For example, if you are listening on <code>&#39;0.0.0.0&#39;</code> and the
client connects on <code>&#39;192.168.1.1&#39;</code>, the value would be <code>&#39;192.168.1.1&#39;</code>.
</p>
<h3>socket.localPort<span><a class="mark" href="#all_socket_localport" id="all_socket_localport">#</a></span></h3>
<p>The numeric representation of the local port. For example,
<code>80</code> or <code>21</code>.
</p>
<h3>socket.bytesRead<span><a class="mark" href="#all_socket_bytesread" id="all_socket_bytesread">#</a></span></h3>
<p>The amount of received bytes.
</p>
<h3>socket.bytesWritten<span><a class="mark" href="#all_socket_byteswritten" id="all_socket_byteswritten">#</a></span></h3>
<p>The amount of bytes sent.
</p>
<p><code>net.Socket</code> instances are <a href="events.html#events_class_events_eventemitter">EventEmitter</a> with the following events:
</p>
<h3>Event: &#39;connect&#39;<span><a class="mark" href="#all_event_connect" id="all_event_connect">#</a></span></h3>
<p>Emitted when a socket connection is successfully established.
See <code>connect()</code>.
</p>
<h3>Event: &#39;data&#39;<span><a class="mark" href="#all_event_data_1" id="all_event_data_1">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Buffer object</span></li>
</div></ul>
<p>Emitted when data is received. The argument <code>data</code> will be a <code>Buffer</code> or
<code>String</code>. Encoding of data is set by <code>socket.setEncoding()</code>.
(See the <a href="stream.html#stream_readable_stream">Readable Stream</a> section for more information.)
</p>
<p>Note that the <strong>data will be lost</strong> if there is no listener when a <code>Socket</code>
emits a <code>&#39;data&#39;</code> event.
</p>
<h3>Event: &#39;end&#39;<span><a class="mark" href="#all_event_end_1" id="all_event_end_1">#</a></span></h3>
<p>Emitted when the other end of the socket sends a FIN packet.
</p>
<p>By default (<code>allowHalfOpen == false</code>) the socket will destroy its file
descriptor once it has written out its pending write queue. However, by
setting <code>allowHalfOpen == true</code> the socket will not automatically <code>end()</code>
its side allowing the user to write arbitrary amounts of data, with the
caveat that the user is required to <code>end()</code> their side now.
</p>
<h3>Event: &#39;timeout&#39;<span><a class="mark" href="#all_event_timeout" id="all_event_timeout">#</a></span></h3>
<p>Emitted if the socket times out from inactivity. This is only to notify that
the socket has been idle. The user must manually close the connection.
</p>
<p>See also: <code>socket.setTimeout()</code>
</p>
<h3>Event: &#39;drain&#39;<span><a class="mark" href="#all_event_drain_1" id="all_event_drain_1">#</a></span></h3>
<p>Emitted when the write buffer becomes empty. Can be used to throttle uploads.
</p>
<p>See also: the return values of <code>socket.write()</code>
</p>
<h3>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_4" id="all_event_error_4">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Error object</span></li>
</div></ul>
<p>Emitted when an error occurs. The <code>&#39;close&#39;</code> event will be called directly
following this event.
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_2" id="all_event_close_2">#</a></span></h3>
<div class="signature"><ul>
<li><code>had_error</code> <span class="type">Boolean</span> true if the socket had a transmission error</li>
</div></ul>
<p>Emitted once the socket is fully closed. The argument <code>had_error</code> is a boolean
which says if the socket was closed due to a transmission error.
</p>
<h2>net.isIP(input)<span><a class="mark" href="#all_net_isip_input" id="all_net_isip_input">#</a></span></h2>
<p>Tests if input is an IP address. Returns 0 for invalid strings,
returns 4 for IP version 4 addresses, and returns 6 for IP version 6 addresses.
</p>
<h2>net.isIPv4(input)<span><a class="mark" href="#all_net_isipv4_input" id="all_net_isipv4_input">#</a></span></h2>
<p>Returns true if input is a version 4 IP address, otherwise returns false.
</p>
<h2>net.isIPv6(input)<span><a class="mark" href="#all_net_isipv6_input" id="all_net_isipv6_input">#</a></span></h2>
<p>Returns true if input is a version 6 IP address, otherwise returns false.
</p>
<h1>UDP / Datagram Sockets<span><a class="mark" href="#all_udp_datagram_sockets" id="all_udp_datagram_sockets">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><!-- name=dgram -->
<p>Datagram sockets are available through <code>require(&#39;dgram&#39;)</code>.
</p>
<p>Important note: the behavior of <code>dgram.Socket#bind()</code> has changed in v0.10
and is always asynchronous now. If you have code that looks like this:
</p>
<pre><code>var s = dgram.createSocket(&#39;udp4&#39;);
s.bind(1234);
s.addMembership(&#39;224.0.0.114&#39;);</code></pre>
<p>You have to change it to this:
</p>
<pre><code>var s = dgram.createSocket(&#39;udp4&#39;);
s.bind(1234, function() {
s.addMembership(&#39;224.0.0.114&#39;);
});</code></pre>
<h2>dgram.createSocket(type, [callback])<span><a class="mark" href="#all_dgram_createsocket_type_callback" id="all_dgram_createsocket_type_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>type</code> String. Either &#39;udp4&#39; or &#39;udp6&#39;</li>
<li><code>callback</code> Function. Attached as a listener to <code>message</code> events.
Optional</li>
<li>Returns: Socket object</li>
</div></ul>
<p>Creates a datagram Socket of the specified types. Valid types are <code>udp4</code>
and <code>udp6</code>.
</p>
<p>Takes an optional callback which is added as a listener for <code>message</code> events.
</p>
<p>Call <code>socket.bind</code> if you want to receive datagrams. <code>socket.bind()</code> will bind
to the &quot;all interfaces&quot; address on a random port (it does the right thing for
both <code>udp4</code> and <code>udp6</code> sockets). You can then retrieve the address and port
with <code>socket.address().address</code> and <code>socket.address().port</code>.
</p>
<h2>Class: dgram.Socket<span><a class="mark" href="#all_class_dgram_socket" id="all_class_dgram_socket">#</a></span></h2>
<p>The dgram Socket class encapsulates the datagram functionality. It
should be created via <code>dgram.createSocket(type, [callback])</code>.
</p>
<h3>Event: &#39;message&#39;<span><a class="mark" href="#all_event_message" id="all_event_message">#</a></span></h3>
<div class="signature"><ul>
<li><code>msg</code> Buffer object. The message</li>
<li><code>rinfo</code> Object. Remote address information</li>
</div></ul>
<p>Emitted when a new datagram is available on a socket. <code>msg</code> is a <code>Buffer</code> and <code>rinfo</code> is
an object with the sender&#39;s address information and the number of bytes in the datagram.
</p>
<h3>Event: &#39;listening&#39;<span><a class="mark" href="#all_event_listening_1" id="all_event_listening_1">#</a></span></h3>
<p>Emitted when a socket starts listening for datagrams. This happens as soon as UDP sockets
are created.
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_3" id="all_event_close_3">#</a></span></h3>
<p>Emitted when a socket is closed with <code>close()</code>. No new <code>message</code> events will be emitted
on this socket.
</p>
<h3>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_5" id="all_event_error_5">#</a></span></h3>
<div class="signature"><ul>
<li><code>exception</code> Error object</li>
</div></ul>
<p>Emitted when an error occurs.
</p>
<h3>socket.send(buf, offset, length, port, address, [callback])<span><a class="mark" href="#all_socket_send_buf_offset_length_port_address_callback" id="all_socket_send_buf_offset_length_port_address_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>buf</code> Buffer object. Message to be sent</li>
<li><code>offset</code> Integer. Offset in the buffer where the message starts.</li>
<li><code>length</code> Integer. Number of bytes in the message.</li>
<li><code>port</code> Integer. Destination port.</li>
<li><code>address</code> String. Destination hostname or IP address.</li>
<li><code>callback</code> Function. Called when the message has been sent. Optional.</li>
</div></ul>
<p>For UDP sockets, the destination port and address must be specified. A string
may be supplied for the <code>address</code> parameter, and it will be resolved with DNS.
</p>
<p>If the address is omitted or is an empty string, <code>&#39;0.0.0.0&#39;</code> or <code>&#39;::0&#39;</code> is used
instead. Depending on the network configuration, those defaults may or may not
work; it&#39;s best to be explicit about the destination address.
</p>
<p>If the socket has not been previously bound with a call to <code>bind</code>, it gets
assigned a random port number and is bound to the &quot;all interfaces&quot; address
(<code>&#39;0.0.0.0&#39;</code> for <code>udp4</code> sockets, <code>&#39;::0&#39;</code> for <code>udp6</code> sockets.)
</p>
<p>An optional callback may be specified to detect DNS errors or for determining
when it&#39;s safe to reuse the <code>buf</code> object. Note that DNS lookups delay the time
to send for at least one tick. The only way to know for sure that the datagram
has been sent is by using a callback.
</p>
<p>Example of sending a UDP packet to a random port on <code>localhost</code>;
</p>
<pre><code>var dgram = require(&#39;dgram&#39;);
var message = new Buffer(&quot;Some bytes&quot;);
var client = dgram.createSocket(&quot;udp4&quot;);
client.send(message, 0, message.length, 41234, &quot;localhost&quot;, function(err, bytes) {
client.close();
});</code></pre>
<p><strong>A Note about UDP datagram size</strong>
</p>
<p>The maximum size of an <code>IPv4/v6</code> datagram depends on the <code>MTU</code> (<em>Maximum Transmission Unit</em>)
and on the <code>Payload Length</code> field size.
</p>
<ul>
<li><p>The <code>Payload Length</code> field is <code>16 bits</code> wide, which means that a normal payload
cannot be larger than 64K octets including internet header and data
(65,507 bytes = 65,535 − 8 bytes UDP header − 20 bytes IP header);
this is generally true for loopback interfaces, but such long datagrams
are impractical for most hosts and networks.</p>
</li>
<li><p>The <code>MTU</code> is the largest size a given link layer technology can support for datagrams.
For any link, <code>IPv4</code> mandates a minimum <code>MTU</code> of <code>68</code> octets, while the recommended <code>MTU</code>
for IPv4 is <code>576</code> (typically recommended as the <code>MTU</code> for dial-up type applications),
whether they arrive whole or in fragments.</p>
<p>For <code>IPv6</code>, the minimum <code>MTU</code> is <code>1280</code> octets, however, the mandatory minimum
fragment reassembly buffer size is <code>1500</code> octets.
The value of <code>68</code> octets is very small, since most current link layer technologies have
a minimum <code>MTU</code> of <code>1500</code> (like Ethernet).</p>
</li>
</ul>
<p>Note that it&#39;s impossible to know in advance the MTU of each link through which
a packet might travel, and that generally sending a datagram greater than
the (receiver) <code>MTU</code> won&#39;t work (the packet gets silently dropped, without
informing the source that the data did not reach its intended recipient).
</p>
<h3>socket.bind(port, [address], [callback])<span><a class="mark" href="#all_socket_bind_port_address_callback" id="all_socket_bind_port_address_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>port</code> Integer</li>
<li><code>address</code> String, Optional</li>
<li><code>callback</code> Function with no parameters, Optional. Callback when
binding is done.</li>
</div></ul>
<p>For UDP sockets, listen for datagrams on a named <code>port</code> and optional
<code>address</code>. If <code>address</code> is not specified, the OS will try to listen on
all addresses. After binding is done, a &quot;listening&quot; event is emitted
and the <code>callback</code>(if specified) is called. Specifying both a
&quot;listening&quot; event listener and <code>callback</code> is not harmful but not very
useful.
</p>
<p>A bound datagram socket keeps the node process running to receive
datagrams.
</p>
<p>If binding fails, an &quot;error&quot; event is generated. In rare case (e.g.
binding a closed socket), an <code>Error</code> may be thrown by this method.
</p>
<p>Example of a UDP server listening on port 41234:
</p>
<pre><code>var dgram = require(&quot;dgram&quot;);
var server = dgram.createSocket(&quot;udp4&quot;);
server.on(&quot;error&quot;, function (err) {
console.log(&quot;server error:\n&quot; + err.stack);
server.close();
});
server.on(&quot;message&quot;, function (msg, rinfo) {
console.log(&quot;server got: &quot; + msg + &quot; from &quot; +
rinfo.address + &quot;:&quot; + rinfo.port);
});
server.on(&quot;listening&quot;, function () {
var address = server.address();
console.log(&quot;server listening &quot; +
address.address + &quot;:&quot; + address.port);
});
server.bind(41234);
// server listening 0.0.0.0:41234</code></pre>
<h3>socket.close()<span><a class="mark" href="#all_socket_close" id="all_socket_close">#</a></span></h3>
<p>Close the underlying socket and stop listening for data on it.
</p>
<h3>socket.address()<span><a class="mark" href="#all_socket_address_1" id="all_socket_address_1">#</a></span></h3>
<p>Returns an object containing the address information for a socket. For UDP sockets,
this object will contain <code>address</code> , <code>family</code> and <code>port</code>.
</p>
<h3>socket.setBroadcast(flag)<span><a class="mark" href="#all_socket_setbroadcast_flag" id="all_socket_setbroadcast_flag">#</a></span></h3>
<div class="signature"><ul>
<li><code>flag</code> Boolean</li>
</div></ul>
<p>Sets or clears the <code>SO_BROADCAST</code> socket option. When this option is set, UDP packets
may be sent to a local interface&#39;s broadcast address.
</p>
<h3>socket.setTTL(ttl)<span><a class="mark" href="#all_socket_setttl_ttl" id="all_socket_setttl_ttl">#</a></span></h3>
<div class="signature"><ul>
<li><code>ttl</code> Integer</li>
</div></ul>
<p>Sets the <code>IP_TTL</code> socket option. TTL stands for &quot;Time to Live,&quot; but in this context it
specifies the number of IP hops that a packet is allowed to go through. Each router or
gateway that forwards a packet decrements the TTL. If the TTL is decremented to 0 by a
router, it will not be forwarded. Changing TTL values is typically done for network
probes or when multicasting.
</p>
<p>The argument to <code>setTTL()</code> is a number of hops between 1 and 255. The default on most
systems is 64.
</p>
<h3>socket.setMulticastTTL(ttl)<span><a class="mark" href="#all_socket_setmulticastttl_ttl" id="all_socket_setmulticastttl_ttl">#</a></span></h3>
<div class="signature"><ul>
<li><code>ttl</code> Integer</li>
</div></ul>
<p>Sets the <code>IP_MULTICAST_TTL</code> socket option. TTL stands for &quot;Time to Live,&quot; but in this
context it specifies the number of IP hops that a packet is allowed to go through,
specifically for multicast traffic. Each router or gateway that forwards a packet
decrements the TTL. If the TTL is decremented to 0 by a router, it will not be forwarded.
</p>
<p>The argument to <code>setMulticastTTL()</code> is a number of hops between 0 and 255. The default on most
systems is 1.
</p>
<h3>socket.setMulticastLoopback(flag)<span><a class="mark" href="#all_socket_setmulticastloopback_flag" id="all_socket_setmulticastloopback_flag">#</a></span></h3>
<div class="signature"><ul>
<li><code>flag</code> Boolean</li>
</div></ul>
<p>Sets or clears the <code>IP_MULTICAST_LOOP</code> socket option. When this option is set, multicast
packets will also be received on the local interface.
</p>
<h3>socket.addMembership(multicastAddress, [multicastInterface])<span><a class="mark" href="#all_socket_addmembership_multicastaddress_multicastinterface" id="all_socket_addmembership_multicastaddress_multicastinterface">#</a></span></h3>
<div class="signature"><ul>
<li><code>multicastAddress</code> String</li>
<li><code>multicastInterface</code> String, Optional</li>
</div></ul>
<p>Tells the kernel to join a multicast group with <code>IP_ADD_MEMBERSHIP</code> socket option.
</p>
<p>If <code>multicastInterface</code> is not specified, the OS will try to add membership to all valid
interfaces.
</p>
<h3>socket.dropMembership(multicastAddress, [multicastInterface])<span><a class="mark" href="#all_socket_dropmembership_multicastaddress_multicastinterface" id="all_socket_dropmembership_multicastaddress_multicastinterface">#</a></span></h3>
<div class="signature"><ul>
<li><code>multicastAddress</code> String</li>
<li><code>multicastInterface</code> String, Optional</li>
</div></ul>
<p>Opposite of <code>addMembership</code> - tells the kernel to leave a multicast group with
<code>IP_DROP_MEMBERSHIP</code> socket option. This is automatically called by the kernel
when the socket is closed or process terminates, so most apps will never need to call
this.
</p>
<p>If <code>multicastInterface</code> is not specified, the OS will try to drop membership to all valid
interfaces.
</p>
<h3>socket.unref()<span><a class="mark" href="#all_socket_unref_1" id="all_socket_unref_1">#</a></span></h3>
<p>Calling <code>unref</code> on a socket will allow the program to exit if this is the only
active socket in the event system. If the socket is already <code>unref</code>d calling
<code>unref</code> again will have no effect.
</p>
<h3>socket.ref()<span><a class="mark" href="#all_socket_ref_1" id="all_socket_ref_1">#</a></span></h3>
<p>Opposite of <code>unref</code>, calling <code>ref</code> on a previously <code>unref</code>d socket will <em>not</em>
let the program exit if it&#39;s the only socket left (the default behavior). If
the socket is <code>ref</code>d calling <code>ref</code> again will have no effect.
</p>
<h1>DNS<span><a class="mark" href="#all_dns" id="all_dns">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>Use <code>require(&#39;dns&#39;)</code> to access this module. All methods in the dns module
use C-Ares except for <code>dns.lookup</code> which uses <code>getaddrinfo(3)</code> in a thread
pool. C-Ares is much faster than <code>getaddrinfo</code> but the system resolver is
more consistent with how other programs operate. When a user does
<code>net.connect(80, &#39;google.com&#39;)</code> or <code>http.get({ host: &#39;google.com&#39; })</code> the
<code>dns.lookup</code> method is used. Users who need to do a large number of lookups
quickly should use the methods that go through C-Ares.
</p>
<p>Here is an example which resolves <code>&#39;www.google.com&#39;</code> then reverse
resolves the IP addresses which are returned.
</p>
<pre><code>var dns = require(&#39;dns&#39;);
dns.resolve4(&#39;www.google.com&#39;, function (err, addresses) {
if (err) throw err;
console.log(&#39;addresses: &#39; + JSON.stringify(addresses));
addresses.forEach(function (a) {
dns.reverse(a, function (err, domains) {
if (err) {
throw err;
}
console.log(&#39;reverse for &#39; + a + &#39;: &#39; + JSON.stringify(domains));
});
});
});</code></pre>
<h2>dns.lookup(domain, [family], callback)<span><a class="mark" href="#all_dns_lookup_domain_family_callback" id="all_dns_lookup_domain_family_callback">#</a></span></h2>
<p>Resolves a domain (e.g. <code>&#39;google.com&#39;</code>) into the first found A (IPv4) or
AAAA (IPv6) record.
The <code>family</code> can be the integer <code>4</code> or <code>6</code>. Defaults to <code>null</code> that indicates
both Ip v4 and v6 address family.
</p>
<p>The callback has arguments <code>(err, address, family)</code>. The <code>address</code> argument
is a string representation of a IP v4 or v6 address. The <code>family</code> argument
is either the integer 4 or 6 and denotes the family of <code>address</code> (not
necessarily the value initially passed to <code>lookup</code>).
</p>
<p>On error, <code>err</code> is an <code>Error</code> object, where <code>err.code</code> is the error code.
Keep in mind that <code>err.code</code> will be set to <code>&#39;ENOENT&#39;</code> not only when
the domain does not exist but also when the lookup fails in other ways
such as no available file descriptors.
</p>
<h2>dns.resolve(domain, [rrtype], callback)<span><a class="mark" href="#all_dns_resolve_domain_rrtype_callback" id="all_dns_resolve_domain_rrtype_callback">#</a></span></h2>
<p>Resolves a domain (e.g. <code>&#39;google.com&#39;</code>) into an array of the record types
specified by rrtype. Valid rrtypes are <code>&#39;A&#39;</code> (IPV4 addresses, default),
<code>&#39;AAAA&#39;</code> (IPV6 addresses), <code>&#39;MX&#39;</code> (mail exchange records), <code>&#39;TXT&#39;</code> (text
records), <code>&#39;SRV&#39;</code> (SRV records), <code>&#39;PTR&#39;</code> (used for reverse IP lookups),
<code>&#39;NS&#39;</code> (name server records) and <code>&#39;CNAME&#39;</code> (canonical name records).
</p>
<p>The callback has arguments <code>(err, addresses)</code>. The type of each item
in <code>addresses</code> is determined by the record type, and described in the
documentation for the corresponding lookup methods below.
</p>
<p>On error, <code>err</code> is an <code>Error</code> object, where <code>err.code</code> is
one of the error codes listed below.
</p>
<h2>dns.resolve4(domain, callback)<span><a class="mark" href="#all_dns_resolve4_domain_callback" id="all_dns_resolve4_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve()</code>, but only for IPv4 queries (<code>A</code> records).
<code>addresses</code> is an array of IPv4 addresses (e.g.
<code>[&#39;74.125.79.104&#39;, &#39;74.125.79.105&#39;, &#39;74.125.79.106&#39;]</code>).
</p>
<h2>dns.resolve6(domain, callback)<span><a class="mark" href="#all_dns_resolve6_domain_callback" id="all_dns_resolve6_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve4()</code> except for IPv6 queries (an <code>AAAA</code> query).
</p>
<h2>dns.resolveMx(domain, callback)<span><a class="mark" href="#all_dns_resolvemx_domain_callback" id="all_dns_resolvemx_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve()</code>, but only for mail exchange queries (<code>MX</code> records).
</p>
<p><code>addresses</code> is an array of MX records, each with a priority and an exchange
attribute (e.g. <code>[{&#39;priority&#39;: 10, &#39;exchange&#39;: &#39;mx.example.com&#39;},...]</code>).
</p>
<h2>dns.resolveTxt(domain, callback)<span><a class="mark" href="#all_dns_resolvetxt_domain_callback" id="all_dns_resolvetxt_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve()</code>, but only for text queries (<code>TXT</code> records).
<code>addresses</code> is an array of the text records available for <code>domain</code> (e.g.,
<code>[&#39;v=spf1 ip4:0.0.0.0 ~all&#39;]</code>).
</p>
<h2>dns.resolveSrv(domain, callback)<span><a class="mark" href="#all_dns_resolvesrv_domain_callback" id="all_dns_resolvesrv_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve()</code>, but only for service records (<code>SRV</code> records).
<code>addresses</code> is an array of the SRV records available for <code>domain</code>. Properties
of SRV records are priority, weight, port, and name (e.g.,
<code>[{&#39;priority&#39;: 10, {&#39;weight&#39;: 5, &#39;port&#39;: 21223, &#39;name&#39;: &#39;service.example.com&#39;}, ...]</code>).
</p>
<h2>dns.resolveNs(domain, callback)<span><a class="mark" href="#all_dns_resolvens_domain_callback" id="all_dns_resolvens_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve()</code>, but only for name server records (<code>NS</code> records).
<code>addresses</code> is an array of the name server records available for <code>domain</code>
(e.g., <code>[&#39;ns1.example.com&#39;, &#39;ns2.example.com&#39;]</code>).
</p>
<h2>dns.resolveCname(domain, callback)<span><a class="mark" href="#all_dns_resolvecname_domain_callback" id="all_dns_resolvecname_domain_callback">#</a></span></h2>
<p>The same as <code>dns.resolve()</code>, but only for canonical name records (<code>CNAME</code>
records). <code>addresses</code> is an array of the canonical name records available for
<code>domain</code> (e.g., <code>[&#39;bar.example.com&#39;]</code>).
</p>
<h2>dns.reverse(ip, callback)<span><a class="mark" href="#all_dns_reverse_ip_callback" id="all_dns_reverse_ip_callback">#</a></span></h2>
<p>Reverse resolves an ip address to an array of domain names.
</p>
<p>The callback has arguments <code>(err, domains)</code>.
</p>
<p>On error, <code>err</code> is an <code>Error</code> object, where <code>err.code</code> is
one of the error codes listed below.
</p>
<h2>Error codes<span><a class="mark" href="#all_error_codes" id="all_error_codes">#</a></span></h2>
<p>Each DNS query can return one of the following error codes:
</p>
<ul>
<li><code>dns.NODATA</code>: DNS server returned answer with no data.</li>
<li><code>dns.FORMERR</code>: DNS server claims query was misformatted.</li>
<li><code>dns.SERVFAIL</code>: DNS server returned general failure.</li>
<li><code>dns.NOTFOUND</code>: Domain name not found.</li>
<li><code>dns.NOTIMP</code>: DNS server does not implement requested operation.</li>
<li><code>dns.REFUSED</code>: DNS server refused query.</li>
<li><code>dns.BADQUERY</code>: Misformatted DNS query.</li>
<li><code>dns.BADNAME</code>: Misformatted domain name.</li>
<li><code>dns.BADFAMILY</code>: Unsupported address family.</li>
<li><code>dns.BADRESP</code>: Misformatted DNS reply.</li>
<li><code>dns.CONNREFUSED</code>: Could not contact DNS servers.</li>
<li><code>dns.TIMEOUT</code>: Timeout while contacting DNS servers.</li>
<li><code>dns.EOF</code>: End of file.</li>
<li><code>dns.FILE</code>: Error reading file.</li>
<li><code>dns.NOMEM</code>: Out of memory.</li>
<li><code>dns.DESTRUCTION</code>: Channel is being destroyed.</li>
<li><code>dns.BADSTR</code>: Misformatted string.</li>
<li><code>dns.BADFLAGS</code>: Illegal flags specified.</li>
<li><code>dns.NONAME</code>: Given hostname is not numeric.</li>
<li><code>dns.BADHINTS</code>: Illegal hints flags specified.</li>
<li><code>dns.NOTINITIALIZED</code>: c-ares library initialization not yet performed.</li>
<li><code>dns.LOADIPHLPAPI</code>: Error loading iphlpapi.dll.</li>
<li><code>dns.ADDRGETNETWORKPARAMS</code>: Could not find GetNetworkParams function.</li>
<li><code>dns.CANCELLED</code>: DNS query cancelled.</li>
</ul>
<h1>HTTP<span><a class="mark" href="#all_http" id="all_http">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>To use the HTTP server and client one must <code>require(&#39;http&#39;)</code>.
</p>
<p>The HTTP interfaces in Node are designed to support many features
of the protocol which have been traditionally difficult to use.
In particular, large, possibly chunk-encoded, messages. The interface is
careful to never buffer entire requests or responses--the
user is able to stream data.
</p>
<p>HTTP message headers are represented by an object like this:
</p>
<pre><code>{ &#39;content-length&#39;: &#39;123&#39;,
&#39;content-type&#39;: &#39;text/plain&#39;,
&#39;connection&#39;: &#39;keep-alive&#39;,
&#39;accept&#39;: &#39;*/*&#39; }</code></pre>
<p>Keys are lowercased. Values are not modified.
</p>
<p>In order to support the full spectrum of possible HTTP applications, Node&#39;s
HTTP API is very low-level. It deals with stream handling and message
parsing only. It parses a message into headers and body but it does not
parse the actual headers or the body.
</p>
<h2>http.STATUS_CODES<span><a class="mark" href="#all_http_status_codes" id="all_http_status_codes">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<p>A collection of all the standard HTTP response status codes, and the
short description of each. For example, <code>http.STATUS_CODES[404] === &#39;Not
Found&#39;</code>.
</p>
<h2>http.createServer([requestListener])<span><a class="mark" href="#all_http_createserver_requestlistener" id="all_http_createserver_requestlistener">#</a></span></h2>
<p>Returns a new web server object.
</p>
<p>The <code>requestListener</code> is a function which is automatically
added to the <code>&#39;request&#39;</code> event.
</p>
<h2>http.createClient([port], [host])<span><a class="mark" href="#all_http_createclient_port_host" id="all_http_createclient_port_host">#</a></span></h2>
<p>This function is <strong>deprecated</strong>; please use <a href="http.html#http_http_request_options_callback">http.request()</a> instead.
Constructs a new HTTP client. <code>port</code> and <code>host</code> refer to the server to be
connected to.
</p>
<h2>Class: http.Server<span><a class="mark" href="#all_class_http_server" id="all_class_http_server">#</a></span></h2>
<p>This is an <a href="events.html#events_class_events_eventemitter">EventEmitter</a> with the following events:
</p>
<h3>Event: &#39;request&#39;<span><a class="mark" href="#all_event_request" id="all_event_request">#</a></span></h3>
<p><code>function (request, response) { }</code>
</p>
<p>Emitted each time there is a request. Note that there may be multiple requests
per connection (in the case of keep-alive connections).
<code>request</code> is an instance of <a href="#http_http_incomingmessage">http.IncomingMessage</a> and <code>response</code> is
an instance of <a href="#http_class_http_serverresponse">http.ServerResponse</a>.
</p>
<h3>Event: &#39;connection&#39;<span><a class="mark" href="#all_event_connection_1" id="all_event_connection_1">#</a></span></h3>
<p><code>function (socket) { }</code>
</p>
<p> When a new TCP stream is established. <code>socket</code> is an object of type
<code>net.Socket</code>. Usually users will not want to access this event. In
particular, the socket will not emit <code>readable</code> events because of how
the protocol parser attaches to the socket. The <code>socket</code> can also be
accessed at <code>request.connection</code>.
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_4" id="all_event_close_4">#</a></span></h3>
<p><code>function () { }</code>
</p>
<p> Emitted when the server closes.
</p>
<h3>Event: &#39;checkContinue&#39;<span><a class="mark" href="#all_event_checkcontinue" id="all_event_checkcontinue">#</a></span></h3>
<p><code>function (request, response) { }</code>
</p>
<p>Emitted each time a request with an http Expect: 100-continue is received.
If this event isn&#39;t listened for, the server will automatically respond
with a 100 Continue as appropriate.
</p>
<p>Handling this event involves calling <a href="#http_response_writecontinue">response.writeContinue()</a> if the client
should continue to send the request body, or generating an appropriate HTTP
response (e.g., 400 Bad Request) if the client should not continue to send the
request body.
</p>
<p>Note that when this event is emitted and handled, the <code>request</code> event will
not be emitted.
</p>
<h3>Event: &#39;connect&#39;<span><a class="mark" href="#all_event_connect_1" id="all_event_connect_1">#</a></span></h3>
<p><code>function (request, socket, head) { }</code>
</p>
<p>Emitted each time a client requests a http CONNECT method. If this event isn&#39;t
listened for, then clients requesting a CONNECT method will have their
connections closed.
</p>
<ul>
<li><code>request</code> is the arguments for the http request, as it is in the request
event.</li>
<li><code>socket</code> is the network socket between the server and client.</li>
<li><code>head</code> is an instance of Buffer, the first packet of the tunneling stream,
this may be empty.</li>
</ul>
<p>After this event is emitted, the request&#39;s socket will not have a <code>data</code>
event listener, meaning you will need to bind to it in order to handle data
sent to the server on that socket.
</p>
<h3>Event: &#39;upgrade&#39;<span><a class="mark" href="#all_event_upgrade" id="all_event_upgrade">#</a></span></h3>
<p><code>function (request, socket, head) { }</code>
</p>
<p>Emitted each time a client requests a http upgrade. If this event isn&#39;t
listened for, then clients requesting an upgrade will have their connections
closed.
</p>
<ul>
<li><code>request</code> is the arguments for the http request, as it is in the request
event.</li>
<li><code>socket</code> is the network socket between the server and client.</li>
<li><code>head</code> is an instance of Buffer, the first packet of the upgraded stream,
this may be empty.</li>
</ul>
<p>After this event is emitted, the request&#39;s socket will not have a <code>data</code>
event listener, meaning you will need to bind to it in order to handle data
sent to the server on that socket.
</p>
<h3>Event: &#39;clientError&#39;<span><a class="mark" href="#all_event_clienterror_1" id="all_event_clienterror_1">#</a></span></h3>
<p><code>function (exception, socket) { }</code>
</p>
<p>If a client connection emits an &#39;error&#39; event - it will forwarded here.
</p>
<p><code>socket</code> is the <code>net.Socket</code> object that the error originated from.
</p>
<h3>server.listen(port, [hostname], [backlog], [callback])<span><a class="mark" href="#all_server_listen_port_hostname_backlog_callback" id="all_server_listen_port_hostname_backlog_callback">#</a></span></h3>
<p>Begin accepting connections on the specified port and hostname. If the
hostname is omitted, the server will accept connections directed to any
IPv4 address (<code>INADDR_ANY</code>).
</p>
<p>To listen to a unix socket, supply a filename instead of port and hostname.
</p>
<p>Backlog is the maximum length of the queue of pending connections.
The actual length will be determined by your OS through sysctl settings such as
<code>tcp_max_syn_backlog</code> and <code>somaxconn</code> on linux. The default value of this
parameter is 511 (not 512).
</p>
<p>This function is asynchronous. The last parameter <code>callback</code> will be added as
a listener for the <a href="net.html#net_event_listening">&#39;listening&#39;</a> event. See also <a href="net.html#net_server_listen_port_host_backlog_callback">net.Server.listen(port)</a>.
</p>
<h3>server.listen(path, [callback])<span><a class="mark" href="#all_server_listen_path_callback_1" id="all_server_listen_path_callback_1">#</a></span></h3>
<p>Start a UNIX socket server listening for connections on the given <code>path</code>.
</p>
<p>This function is asynchronous. The last parameter <code>callback</code> will be added as
a listener for the <a href="net.html#net_event_listening">&#39;listening&#39;</a> event. See also <a href="net.html#net_server_listen_path_callback">net.Server.listen(path)</a>.
</p>
<h3>server.listen(handle, [callback])<span><a class="mark" href="#all_server_listen_handle_callback_1" id="all_server_listen_handle_callback_1">#</a></span></h3>
<div class="signature"><ul>
<li><code>handle</code> <span class="type">Object</span></li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>The <code>handle</code> object can be set to either a server or socket (anything
with an underlying <code>_handle</code> member), or a <code>{fd: &lt;n&gt;}</code> object.
</p>
<p>This will cause the server to accept connections on the specified
handle, but it is presumed that the file descriptor or handle has
already been bound to a port or domain socket.
</p>
<p>Listening on a file descriptor is not supported on Windows.
</p>
<p>This function is asynchronous. The last parameter <code>callback</code> will be added as
a listener for the <a href="net.html#event_listening_">&#39;listening&#39;</a> event.
See also <a href="net.html#net_server_listen_handle_callback">net.Server.listen()</a>.
</p>
<h3>server.close([callback])<span><a class="mark" href="#all_server_close_callback_1" id="all_server_close_callback_1">#</a></span></h3>
<p>Stops the server from accepting new connections. See <a href="net.html#net_server_close_callback">net.Server.close()</a>.
</p>
<h3>server.maxHeadersCount<span><a class="mark" href="#all_server_maxheaderscount" id="all_server_maxheaderscount">#</a></span></h3>
<p>Limits maximum incoming headers count, equal to 1000 by default. If set to 0 -
no limit will be applied.
</p>
<h3>server.setTimeout(msecs, callback)<span><a class="mark" href="#all_server_settimeout_msecs_callback" id="all_server_settimeout_msecs_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>msecs</code> <span class="type">Number</span></li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>Sets the timeout value for sockets, and emits a <code>&#39;timeout&#39;</code> event on
the Server object, passing the socket as an argument, if a timeout
occurs.
</p>
<p>If there is a <code>&#39;timeout&#39;</code> event listener on the Server object, then it
will be called with the timed-out socket as an argument.
</p>
<p>By default, the Server&#39;s timeout value is 2 minutes, and sockets are
destroyed automatically if they time out. However, if you assign a
callback to the Server&#39;s <code>&#39;timeout&#39;</code> event, then you are responsible
for handling socket timeouts.
</p>
<h3>server.timeout<span><a class="mark" href="#all_server_timeout" id="all_server_timeout">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Number</span> Default = 120000 (2 minutes)</li>
</div></ul>
<p>The number of milliseconds of inactivity before a socket is presumed
to have timed out.
</p>
<p>Note that the socket timeout logic is set up on connection, so
changing this value only affects <em>new</em> connections to the server, not
any existing connections.
</p>
<p>Set to 0 to disable any kind of automatic timeout behavior on incoming
connections.
</p>
<h2>Class: http.ServerResponse<span><a class="mark" href="#all_class_http_serverresponse" id="all_class_http_serverresponse">#</a></span></h2>
<p>This object is created internally by a HTTP server--not by the user. It is
passed as the second parameter to the <code>&#39;request&#39;</code> event.
</p>
<p>The response implements the <a href="stream.html#stream_writable_stream">Writable Stream</a> interface. This is an
<a href="events.html#events_class_events_eventemitter">EventEmitter</a> with the following events:
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_5" id="all_event_close_5">#</a></span></h3>
<p><code>function () { }</code>
</p>
<p>Indicates that the underlying connection was terminated before
<a href="#http_response_end_data_encoding">response.end()</a> was called or able to flush.
</p>
<h3>Event: &#39;finish&#39;<span><a class="mark" href="#all_event_finish_1" id="all_event_finish_1">#</a></span></h3>
<p><code>function () { }</code>
</p>
<p>Emitted when the response has been sent. More specifically, this event is
emitted when the last segment of the response headers and body have been
handed off to the operating system for transmission over the network. It
does not imply that the client has received anything yet.
</p>
<p>After this event, no more events will be emitted on the response object.
</p>
<h3>response.writeContinue()<span><a class="mark" href="#all_response_writecontinue" id="all_response_writecontinue">#</a></span></h3>
<p>Sends a HTTP/1.1 100 Continue message to the client, indicating that
the request body should be sent. See the <a href="#http_event_checkcontinue">&#39;checkContinue&#39;</a> event on <code>Server</code>.
</p>
<h3>response.writeHead(statusCode, [reasonPhrase], [headers])<span><a class="mark" href="#all_response_writehead_statuscode_reasonphrase_headers" id="all_response_writehead_statuscode_reasonphrase_headers">#</a></span></h3>
<p>Sends a response header to the request. The status code is a 3-digit HTTP
status code, like <code>404</code>. The last argument, <code>headers</code>, are the response headers.
Optionally one can give a human-readable <code>reasonPhrase</code> as the second
argument.
</p>
<p>Example:
</p>
<pre><code>var body = &#39;hello world&#39;;
response.writeHead(200, {
&#39;Content-Length&#39;: body.length,
&#39;Content-Type&#39;: &#39;text/plain&#39; });</code></pre>
<p>This method must only be called once on a message and it must
be called before <a href="#http_response_end_data_encoding">response.end()</a> is called.
</p>
<p>If you call <a href="#http_response_write_chunk_encoding">response.write()</a> or <a href="#http_response_end_data_encoding">response.end()</a> before calling this, the
implicit/mutable headers will be calculated and call this function for you.
</p>
<p>Note: that Content-Length is given in bytes not characters. The above example
works because the string <code>&#39;hello world&#39;</code> contains only single byte characters.
If the body contains higher coded characters then <code>Buffer.byteLength()</code>
should be used to determine the number of bytes in a given encoding.
And Node does not check whether Content-Length and the length of the body
which has been transmitted are equal or not.
</p>
<h3>response.setTimeout(msecs, callback)<span><a class="mark" href="#all_response_settimeout_msecs_callback" id="all_response_settimeout_msecs_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>msecs</code> <span class="type">Number</span></li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>Sets the Socket&#39;s timeout value to <code>msecs</code>. If a callback is
provided, then it is added as a listener on the <code>&#39;timeout&#39;</code> event on
the response object.
</p>
<p>If no <code>&#39;timeout&#39;</code> listener is added to the request, the response, or
the server, then sockets are destroyed when they time out. If you
assign a handler on the request, the response, or the server&#39;s
<code>&#39;timeout&#39;</code> events, then it is your responsibility to handle timed out
sockets.
</p>
<h3>response.statusCode<span><a class="mark" href="#all_response_statuscode" id="all_response_statuscode">#</a></span></h3>
<p>When using implicit headers (not calling <a href="#http_response_writehead_statuscode_reasonphrase_headers">response.writeHead()</a> explicitly),
this property controls the status code that will be sent to the client when
the headers get flushed.
</p>
<p>Example:
</p>
<pre><code>response.statusCode = 404;</code></pre>
<p>After response header was sent to the client, this property indicates the
status code which was sent out.
</p>
<h3>response.setHeader(name, value)<span><a class="mark" href="#all_response_setheader_name_value" id="all_response_setheader_name_value">#</a></span></h3>
<p>Sets a single header value for implicit headers. If this header already exists
in the to-be-sent headers, its value will be replaced. Use an array of strings
here if you need to send multiple headers with the same name.
</p>
<p>Example:
</p>
<pre><code>response.setHeader(&quot;Content-Type&quot;, &quot;text/html&quot;);</code></pre>
<p>or
</p>
<pre><code>response.setHeader(&quot;Set-Cookie&quot;, [&quot;type=ninja&quot;, &quot;language=javascript&quot;]);</code></pre>
<h3>response.headersSent<span><a class="mark" href="#all_response_headerssent" id="all_response_headerssent">#</a></span></h3>
<p>Boolean (read-only). True if headers were sent, false otherwise.
</p>
<h3>response.sendDate<span><a class="mark" href="#all_response_senddate" id="all_response_senddate">#</a></span></h3>
<p>When true, the Date header will be automatically generated and sent in
the response if it is not already present in the headers. Defaults to true.
</p>
<p>This should only be disabled for testing; HTTP requires the Date header
in responses.
</p>
<h3>response.getHeader(name)<span><a class="mark" href="#all_response_getheader_name" id="all_response_getheader_name">#</a></span></h3>
<p>Reads out a header that&#39;s already been queued but not sent to the client. Note
that the name is case insensitive. This can only be called before headers get
implicitly flushed.
</p>
<p>Example:
</p>
<pre><code>var contentType = response.getHeader(&#39;content-type&#39;);</code></pre>
<h3>response.removeHeader(name)<span><a class="mark" href="#all_response_removeheader_name" id="all_response_removeheader_name">#</a></span></h3>
<p>Removes a header that&#39;s queued for implicit sending.
</p>
<p>Example:
</p>
<pre><code>response.removeHeader(&quot;Content-Encoding&quot;);</code></pre>
<h3>response.write(chunk, [encoding])<span><a class="mark" href="#all_response_write_chunk_encoding" id="all_response_write_chunk_encoding">#</a></span></h3>
<p>If this method is called and <a href="#http_response_writehead_statuscode_reasonphrase_headers">response.writeHead()</a> has not been called,
it will switch to implicit header mode and flush the implicit headers.
</p>
<p>This sends a chunk of the response body. This method may
be called multiple times to provide successive parts of the body.
</p>
<p><code>chunk</code> can be a string or a buffer. If <code>chunk</code> is a string,
the second parameter specifies how to encode it into a byte stream.
By default the <code>encoding</code> is <code>&#39;utf8&#39;</code>.
</p>
<p><strong>Note</strong>: This is the raw HTTP body and has nothing to do with
higher-level multi-part body encodings that may be used.
</p>
<p>The first time <code>response.write()</code> is called, it will send the buffered
header information and the first body to the client. The second time
<code>response.write()</code> is called, Node assumes you&#39;re going to be streaming
data, and sends that separately. That is, the response is buffered up to the
first chunk of body.
</p>
<p>Returns <code>true</code> if the entire data was flushed successfully to the kernel
buffer. Returns <code>false</code> if all or part of the data was queued in user memory.
<code>&#39;drain&#39;</code> will be emitted when the buffer is again free.
</p>
<h3>response.addTrailers(headers)<span><a class="mark" href="#all_response_addtrailers_headers" id="all_response_addtrailers_headers">#</a></span></h3>
<p>This method adds HTTP trailing headers (a header but at the end of the
message) to the response.
</p>
<p>Trailers will <strong>only</strong> be emitted if chunked encoding is used for the
response; if it is not (e.g., if the request was HTTP/1.0), they will
be silently discarded.
</p>
<p>Note that HTTP requires the <code>Trailer</code> header to be sent if you intend to
emit trailers, with a list of the header fields in its value. E.g.,
</p>
<pre><code>response.writeHead(200, { &#39;Content-Type&#39;: &#39;text/plain&#39;,
&#39;Trailer&#39;: &#39;Content-MD5&#39; });
response.write(fileData);
response.addTrailers({&#39;Content-MD5&#39;: &quot;7895bf4b8828b55ceaf47747b4bca667&quot;});
response.end();</code></pre>
<h3>response.end([data], [encoding])<span><a class="mark" href="#all_response_end_data_encoding" id="all_response_end_data_encoding">#</a></span></h3>
<p>This method signals to the server that all of the response headers and body
have been sent; that server should consider this message complete.
The method, <code>response.end()</code>, MUST be called on each
response.
</p>
<p>If <code>data</code> is specified, it is equivalent to calling <code>response.write(data, encoding)</code>
followed by <code>response.end()</code>.
</p>
<h2>http.request(options, [callback])<span><a class="mark" href="#all_http_request_options_callback" id="all_http_request_options_callback">#</a></span></h2>
<p>Node maintains several connections per server to make HTTP requests.
This function allows one to transparently issue requests.
</p>
<p><code>options</code> can be an object or a string. If <code>options</code> is a string, it is
automatically parsed with <a href="url.html#url_url_parse_urlstr_parsequerystring_slashesdenotehost">url.parse()</a>.
</p>
<p>Options:
</p>
<ul>
<li><code>host</code>: A domain name or IP address of the server to issue the request to.
Defaults to <code>&#39;localhost&#39;</code>.</li>
<li><code>hostname</code>: To support <code>url.parse()</code> <code>hostname</code> is preferred over <code>host</code></li>
<li><code>port</code>: Port of remote server. Defaults to 80.</li>
<li><code>localAddress</code>: Local interface to bind for network connections.</li>
<li><code>socketPath</code>: Unix Domain Socket (use one of host:port or socketPath)</li>
<li><code>method</code>: A string specifying the HTTP request method. Defaults to <code>&#39;GET&#39;</code>.</li>
<li><code>path</code>: Request path. Defaults to <code>&#39;/&#39;</code>. Should include query string if any.
E.G. <code>&#39;/index.html?page=12&#39;</code></li>
<li><code>headers</code>: An object containing request headers.</li>
<li><code>auth</code>: Basic authentication i.e. <code>&#39;user:password&#39;</code> to compute an
Authorization header.</li>
<li><code>agent</code>: Controls <a href="#https_class_https_agent">Agent</a> behavior. When an Agent is used request will
default to <code>Connection: keep-alive</code>. Possible values:<ul>
<li><code>undefined</code> (default): use <a href="#http_http_globalagent">global Agent</a> for this host and port.</li>
<li><code>Agent</code> object: explicitly use the passed in <code>Agent</code>.</li>
<li><code>false</code>: opts out of connection pooling with an Agent, defaults request to
<code>Connection: close</code>.</li>
</ul>
</li>
</ul>
<p>The optional <code>callback</code> parameter will be added as a one time listener for
the <a href="#http_event_response">&#39;response&#39;</a> event.
</p>
<p><code>http.request()</code> returns an instance of the <a href="#http_class_http_clientrequest">http.ClientRequest</a>
class. The <code>ClientRequest</code> instance is a writable stream. If one needs to
upload a file with a POST request, then write to the <code>ClientRequest</code> object.
</p>
<p>Example:
</p>
<pre><code>var options = {
hostname: &#39;www.google.com&#39;,
port: 80,
path: &#39;/upload&#39;,
method: &#39;POST&#39;
};
var req = http.request(options, function(res) {
console.log(&#39;STATUS: &#39; + res.statusCode);
console.log(&#39;HEADERS: &#39; + JSON.stringify(res.headers));
res.setEncoding(&#39;utf8&#39;);
res.on(&#39;data&#39;, function (chunk) {
console.log(&#39;BODY: &#39; + chunk);
});
});
req.on(&#39;error&#39;, function(e) {
console.log(&#39;problem with request: &#39; + e.message);
});
// write data to request body
req.write(&#39;data\n&#39;);
req.write(&#39;data\n&#39;);
req.end();</code></pre>
<p>Note that in the example <code>req.end()</code> was called. With <code>http.request()</code> one
must always call <code>req.end()</code> to signify that you&#39;re done with the request -
even if there is no data being written to the request body.
</p>
<p>If any error is encountered during the request (be that with DNS resolution,
TCP level errors, or actual HTTP parse errors) an <code>&#39;error&#39;</code> event is emitted
on the returned request object.
</p>
<p>There are a few special headers that should be noted.
</p>
<ul>
<li><p>Sending a &#39;Connection: keep-alive&#39; will notify Node that the connection to
the server should be persisted until the next request.</p>
</li>
<li><p>Sending a &#39;Content-length&#39; header will disable the default chunked encoding.</p>
</li>
<li><p>Sending an &#39;Expect&#39; header will immediately send the request headers.
Usually, when sending &#39;Expect: 100-continue&#39;, you should both set a timeout
and listen for the <code>continue</code> event. See RFC2616 Section 8.2.3 for more
information.</p>
</li>
<li><p>Sending an Authorization header will override using the <code>auth</code> option
to compute basic authentication.</p>
</li>
</ul>
<h2>http.get(options, [callback])<span><a class="mark" href="#all_http_get_options_callback" id="all_http_get_options_callback">#</a></span></h2>
<p>Since most requests are GET requests without bodies, Node provides this
convenience method. The only difference between this method and <code>http.request()</code>
is that it sets the method to GET and calls <code>req.end()</code> automatically.
</p>
<p>Example:
</p>
<pre><code>http.get(&quot;http://www.google.com/index.html&quot;, function(res) {
console.log(&quot;Got response: &quot; + res.statusCode);
}).on(&#39;error&#39;, function(e) {
console.log(&quot;Got error: &quot; + e.message);
});</code></pre>
<h2>Class: http.Agent<span><a class="mark" href="#all_class_http_agent" id="all_class_http_agent">#</a></span></h2>
<p>In node 0.5.3+ there is a new implementation of the HTTP Agent which is used
for pooling sockets used in HTTP client requests.
</p>
<p>Previously, a single agent instance helped pool for a single host+port. The
current implementation now holds sockets for any number of hosts.
</p>
<p>The current HTTP Agent also defaults client requests to using
Connection:keep-alive. If no pending HTTP requests are waiting on a socket
to become free the socket is closed. This means that node&#39;s pool has the
benefit of keep-alive when under load but still does not require developers
to manually close the HTTP clients using keep-alive.
</p>
<p>Sockets are removed from the agent&#39;s pool when the socket emits either a
&quot;close&quot; event or a special &quot;agentRemove&quot; event. This means that if you intend
to keep one HTTP request open for a long time and don&#39;t want it to stay in the
pool you can do something along the lines of:
</p>
<pre><code>http.get(options, function(res) {
// Do stuff
}).on(&quot;socket&quot;, function (socket) {
socket.emit(&quot;agentRemove&quot;);
});</code></pre>
<p>Alternatively, you could just opt out of pooling entirely using <code>agent:false</code>:
</p>
<pre><code>http.get({hostname:&#39;localhost&#39;, port:80, path:&#39;/&#39;, agent:false}, function (res) {
// Do stuff
})</code></pre>
<h3>agent.maxSockets<span><a class="mark" href="#all_agent_maxsockets" id="all_agent_maxsockets">#</a></span></h3>
<p>By default set to 5. Determines how many concurrent sockets the agent can have
open per host.
</p>
<h3>agent.sockets<span><a class="mark" href="#all_agent_sockets" id="all_agent_sockets">#</a></span></h3>
<p>An object which contains arrays of sockets currently in use by the Agent. Do not
modify.
</p>
<h3>agent.requests<span><a class="mark" href="#all_agent_requests" id="all_agent_requests">#</a></span></h3>
<p>An object which contains queues of requests that have not yet been assigned to
sockets. Do not modify.
</p>
<h2>http.globalAgent<span><a class="mark" href="#all_http_globalagent" id="all_http_globalagent">#</a></span></h2>
<p>Global instance of Agent which is used as the default for all http client
requests.
</p>
<h2>Class: http.ClientRequest<span><a class="mark" href="#all_class_http_clientrequest" id="all_class_http_clientrequest">#</a></span></h2>
<p>This object is created internally and returned from <code>http.request()</code>. It
represents an <em>in-progress</em> request whose header has already been queued. The
header is still mutable using the <code>setHeader(name, value)</code>, <code>getHeader(name)</code>,
<code>removeHeader(name)</code> API. The actual header will be sent along with the first
data chunk or when closing the connection.
</p>
<p>To get the response, add a listener for <code>&#39;response&#39;</code> to the request object.
<code>&#39;response&#39;</code> will be emitted from the request object when the response
headers have been received. The <code>&#39;response&#39;</code> event is executed with one
argument which is an instance of <a href="#http_http_incomingmessage">http.IncomingMessage</a>.
</p>
<p>During the <code>&#39;response&#39;</code> event, one can add listeners to the
response object; particularly to listen for the <code>&#39;data&#39;</code> event.
</p>
<p>If no <code>&#39;response&#39;</code> handler is added, then the response will be
entirely discarded. However, if you add a <code>&#39;response&#39;</code> event handler,
then you <strong>must</strong> consume the data from the response object, either by
calling <code>response.read()</code> whenever there is a <code>&#39;readable&#39;</code> event, or
by adding a <code>&#39;data&#39;</code> handler, or by calling the <code>.resume()</code> method.
Until the data is consumed, the <code>&#39;end&#39;</code> event will not fire. Also, until
the data is read it will consume memory that can eventually lead to a
&#39;process out of memory&#39; error.
</p>
<p>Note: Node does not check whether Content-Length and the length of the body
which has been transmitted are equal or not.
</p>
<p>The request implements the <a href="stream.html#stream_writable_stream">Writable Stream</a> interface. This is an
<a href="events.html#events_class_events_eventemitter">EventEmitter</a> with the following events:
</p>
<h3>Event &#39;response&#39;<span><a class="mark" href="#all_event_response" id="all_event_response">#</a></span></h3>
<p><code>function (response) { }</code>
</p>
<p>Emitted when a response is received to this request. This event is emitted only
once. The <code>response</code> argument will be an instance of <a href="#http_http_incomingmessage">http.IncomingMessage</a>.
</p>
<p>Options:
</p>
<ul>
<li><code>host</code>: A domain name or IP address of the server to issue the request to.</li>
<li><code>port</code>: Port of remote server.</li>
<li><code>socketPath</code>: Unix Domain Socket (use one of host:port or socketPath)</li>
</ul>
<h3>Event: &#39;socket&#39;<span><a class="mark" href="#all_event_socket" id="all_event_socket">#</a></span></h3>
<p><code>function (socket) { }</code>
</p>
<p>Emitted after a socket is assigned to this request.
</p>
<h3>Event: &#39;connect&#39;<span><a class="mark" href="#all_event_connect_2" id="all_event_connect_2">#</a></span></h3>
<p><code>function (response, socket, head) { }</code>
</p>
<p>Emitted each time a server responds to a request with a CONNECT method. If this
event isn&#39;t being listened for, clients receiving a CONNECT method will have
their connections closed.
</p>
<p>A client server pair that show you how to listen for the <code>connect</code> event.
</p>
<pre><code>var http = require(&#39;http&#39;);
var net = require(&#39;net&#39;);
var url = require(&#39;url&#39;);
// Create an HTTP tunneling proxy
var proxy = http.createServer(function (req, res) {
res.writeHead(200, {&#39;Content-Type&#39;: &#39;text/plain&#39;});
res.end(&#39;okay&#39;);
});
proxy.on(&#39;connect&#39;, function(req, cltSocket, head) {
// connect to an origin server
var srvUrl = url.parse(&#39;http://&#39; + req.url);
var srvSocket = net.connect(srvUrl.port, srvUrl.hostname, function() {
cltSocket.write(&#39;HTTP/1.1 200 Connection Established\r\n&#39; +
&#39;Proxy-agent: Node-Proxy\r\n&#39; +
&#39;\r\n&#39;);
srvSocket.write(head);
srvSocket.pipe(cltSocket);
cltSocket.pipe(srvSocket);
});
});
// now that proxy is running
proxy.listen(1337, &#39;127.0.0.1&#39;, function() {
// make a request to a tunneling proxy
var options = {
port: 1337,
hostname: &#39;127.0.0.1&#39;,
method: &#39;CONNECT&#39;,
path: &#39;www.google.com:80&#39;
};
var req = http.request(options);
req.end();
req.on(&#39;connect&#39;, function(res, socket, head) {
console.log(&#39;got connected!&#39;);
// make a request over an HTTP tunnel
socket.write(&#39;GET / HTTP/1.1\r\n&#39; +
&#39;Host: www.google.com:80\r\n&#39; +
&#39;Connection: close\r\n&#39; +
&#39;\r\n&#39;);
socket.on(&#39;data&#39;, function(chunk) {
console.log(chunk.toString());
});
socket.on(&#39;end&#39;, function() {
proxy.close();
});
});
});</code></pre>
<h3>Event: &#39;upgrade&#39;<span><a class="mark" href="#all_event_upgrade_1" id="all_event_upgrade_1">#</a></span></h3>
<p><code>function (response, socket, head) { }</code>
</p>
<p>Emitted each time a server responds to a request with an upgrade. If this
event isn&#39;t being listened for, clients receiving an upgrade header will have
their connections closed.
</p>
<p>A client server pair that show you how to listen for the <code>upgrade</code> event.
</p>
<pre><code>var http = require(&#39;http&#39;);
// Create an HTTP server
var srv = http.createServer(function (req, res) {
res.writeHead(200, {&#39;Content-Type&#39;: &#39;text/plain&#39;});
res.end(&#39;okay&#39;);
});
srv.on(&#39;upgrade&#39;, function(req, socket, head) {
socket.write(&#39;HTTP/1.1 101 Web Socket Protocol Handshake\r\n&#39; +
&#39;Upgrade: WebSocket\r\n&#39; +
&#39;Connection: Upgrade\r\n&#39; +
&#39;\r\n&#39;);
socket.pipe(socket); // echo back
});
// now that server is running
srv.listen(1337, &#39;127.0.0.1&#39;, function() {
// make a request
var options = {
port: 1337,
hostname: &#39;127.0.0.1&#39;,
headers: {
&#39;Connection&#39;: &#39;Upgrade&#39;,
&#39;Upgrade&#39;: &#39;websocket&#39;
}
};
var req = http.request(options);
req.end();
req.on(&#39;upgrade&#39;, function(res, socket, upgradeHead) {
console.log(&#39;got upgraded!&#39;);
socket.end();
process.exit(0);
});
});</code></pre>
<h3>Event: &#39;continue&#39;<span><a class="mark" href="#all_event_continue" id="all_event_continue">#</a></span></h3>
<p><code>function () { }</code>
</p>
<p>Emitted when the server sends a &#39;100 Continue&#39; HTTP response, usually because
the request contained &#39;Expect: 100-continue&#39;. This is an instruction that
the client should send the request body.
</p>
<h3>request.write(chunk, [encoding])<span><a class="mark" href="#all_request_write_chunk_encoding" id="all_request_write_chunk_encoding">#</a></span></h3>
<p>Sends a chunk of the body. By calling this method
many times, the user can stream a request body to a
server--in that case it is suggested to use the
<code>[&#39;Transfer-Encoding&#39;, &#39;chunked&#39;]</code> header line when
creating the request.
</p>
<p>The <code>chunk</code> argument should be a <a href="buffer.html#buffer_buffer">Buffer</a> or a string.
</p>
<p>The <code>encoding</code> argument is optional and only applies when <code>chunk</code> is a string.
Defaults to <code>&#39;utf8&#39;</code>.
</p>
<h3>request.end([data], [encoding])<span><a class="mark" href="#all_request_end_data_encoding" id="all_request_end_data_encoding">#</a></span></h3>
<p>Finishes sending the request. If any parts of the body are
unsent, it will flush them to the stream. If the request is
chunked, this will send the terminating <code>&#39;0\r\n\r\n&#39;</code>.
</p>
<p>If <code>data</code> is specified, it is equivalent to calling
<code>request.write(data, encoding)</code> followed by <code>request.end()</code>.
</p>
<h3>request.abort()<span><a class="mark" href="#all_request_abort" id="all_request_abort">#</a></span></h3>
<p>Aborts a request. (New since v0.3.8.)
</p>
<h3>request.setTimeout(timeout, [callback])<span><a class="mark" href="#all_request_settimeout_timeout_callback" id="all_request_settimeout_timeout_callback">#</a></span></h3>
<p>Once a socket is assigned to this request and is connected
<a href="net.html#net_socket_settimeout_timeout_callback">socket.setTimeout()</a> will be called.
</p>
<h3>request.setNoDelay([noDelay])<span><a class="mark" href="#all_request_setnodelay_nodelay" id="all_request_setnodelay_nodelay">#</a></span></h3>
<p>Once a socket is assigned to this request and is connected
<a href="net.html#net_socket_setnodelay_nodelay">socket.setNoDelay()</a> will be called.
</p>
<h3>request.setSocketKeepAlive([enable], [initialDelay])<span><a class="mark" href="#all_request_setsocketkeepalive_enable_initialdelay" id="all_request_setsocketkeepalive_enable_initialdelay">#</a></span></h3>
<p>Once a socket is assigned to this request and is connected
<a href="net.html#net_socket_setkeepalive_enable_initialdelay">socket.setKeepAlive()</a> will be called.
</p>
<h2>http.IncomingMessage<span><a class="mark" href="#all_http_incomingmessage" id="all_http_incomingmessage">#</a></span></h2>
<p>An <code>IncomingMessage</code> object is created by <a href="#http_class_http_server">http.Server</a> or
<a href="#http_class_http_clientrequest">http.ClientRequest</a> and passed as the first argument to the <code>&#39;request&#39;</code>
and <code>&#39;response&#39;</code> event respectively. It may be used to access response status,
headers and data.
</p>
<p>It implements the <a href="stream.html#stream_readable_stream">Readable Stream</a> interface, as well as the
following additional events, methods, and properties.
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_6" id="all_event_close_6">#</a></span></h3>
<p><code>function () { }</code>
</p>
<p>Indicates that the underlaying connection was closed.
Just like <code>&#39;end&#39;</code>, this event occurs only once per response.
</p>
<h3>message.httpVersion<span><a class="mark" href="#all_message_httpversion" id="all_message_httpversion">#</a></span></h3>
<p>In case of server request, the HTTP version sent by the client. In the case of
client response, the HTTP version of the connected-to server.
Probably either <code>&#39;1.1&#39;</code> or <code>&#39;1.0&#39;</code>.
</p>
<p>Also <code>response.httpVersionMajor</code> is the first integer and
<code>response.httpVersionMinor</code> is the second.
</p>
<h3>message.headers<span><a class="mark" href="#all_message_headers" id="all_message_headers">#</a></span></h3>
<p>The request/response headers object.
</p>
<p>Read only map of header names and values. Header names are lower-cased.
Example:
</p>
<pre><code>// Prints something like:
//
// { &#39;user-agent&#39;: &#39;curl/7.22.0&#39;,
// host: &#39;127.0.0.1:8000&#39;,
// accept: &#39;*/*&#39; }
console.log(request.headers);</code></pre>
<h3>message.trailers<span><a class="mark" href="#all_message_trailers" id="all_message_trailers">#</a></span></h3>
<p>The request/response trailers object. Only populated after the &#39;end&#39; event.
</p>
<h3>message.setTimeout(msecs, callback)<span><a class="mark" href="#all_message_settimeout_msecs_callback" id="all_message_settimeout_msecs_callback">#</a></span></h3>
<div class="signature"><ul>
<li><code>msecs</code> <span class="type">Number</span></li>
<li><code>callback</code> <span class="type">Function</span></li>
</div></ul>
<p>Calls <code>message.connection.setTimeout(msecs, callback)</code>.
</p>
<h3>message.method<span><a class="mark" href="#all_message_method" id="all_message_method">#</a></span></h3>
<p><strong>Only valid for request obtained from <a href="#http_class_http_server">http.Server</a>.</strong>
</p>
<p>The request method as a string. Read only. Example:
<code>&#39;GET&#39;</code>, <code>&#39;DELETE&#39;</code>.
</p>
<h3>message.url<span><a class="mark" href="#all_message_url" id="all_message_url">#</a></span></h3>
<p><strong>Only valid for request obtained from <a href="#http_class_http_server">http.Server</a>.</strong>
</p>
<p>Request URL string. This contains only the URL that is
present in the actual HTTP request. If the request is:
</p>
<pre><code>GET /status?name=ryan HTTP/1.1\r\n
Accept: text/plain\r\n
\r\n</code></pre>
<p>Then <code>request.url</code> will be:
</p>
<pre><code>&#39;/status?name=ryan&#39;</code></pre>
<p>If you would like to parse the URL into its parts, you can use
<code>require(&#39;url&#39;).parse(request.url)</code>. Example:
</p>
<pre><code>node&gt; require(&#39;url&#39;).parse(&#39;/status?name=ryan&#39;)
{ href: &#39;/status?name=ryan&#39;,
search: &#39;?name=ryan&#39;,
query: &#39;name=ryan&#39;,
pathname: &#39;/status&#39; }</code></pre>
<p>If you would like to extract the params from the query string,
you can use the <code>require(&#39;querystring&#39;).parse</code> function, or pass
<code>true</code> as the second argument to <code>require(&#39;url&#39;).parse</code>. Example:
</p>
<pre><code>node&gt; require(&#39;url&#39;).parse(&#39;/status?name=ryan&#39;, true)
{ href: &#39;/status?name=ryan&#39;,
search: &#39;?name=ryan&#39;,
query: { name: &#39;ryan&#39; },
pathname: &#39;/status&#39; }</code></pre>
<h3>message.statusCode<span><a class="mark" href="#all_message_statuscode" id="all_message_statuscode">#</a></span></h3>
<p><strong>Only valid for response obtained from <code>http.ClientRequest</code>.</strong>
</p>
<p>The 3-digit HTTP response status code. E.G. <code>404</code>.
</p>
<h3>message.socket<span><a class="mark" href="#all_message_socket" id="all_message_socket">#</a></span></h3>
<p>The <code>net.Socket</code> object associated with the connection.
</p>
<p>With HTTPS support, use request.connection.verifyPeer() and
request.connection.getPeerCertificate() to obtain the client&#39;s
authentication details.
</p>
<h1>HTTPS<span><a class="mark" href="#all_https" id="all_https">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>HTTPS is the HTTP protocol over TLS/SSL. In Node this is implemented as a
separate module.
</p>
<h2>Class: https.Server<span><a class="mark" href="#all_class_https_server" id="all_class_https_server">#</a></span></h2>
<p>This class is a subclass of <code>tls.Server</code> and emits events same as
<code>http.Server</code>. See <code>http.Server</code> for more information.
</p>
<h2>https.createServer(options, [requestListener])<span><a class="mark" href="#all_https_createserver_options_requestlistener" id="all_https_createserver_options_requestlistener">#</a></span></h2>
<p>Returns a new HTTPS web server object. The <code>options</code> is similar to
<a href="tls.html#tls_tls_createserver_options_secureconnectionlistener">tls.createServer()</a>. The <code>requestListener</code> is a function which is
automatically added to the <code>&#39;request&#39;</code> event.
</p>
<p>Example:
</p>
<pre><code>// curl -k https://localhost:8000/
var https = require(&#39;https&#39;);
var fs = require(&#39;fs&#39;);
var options = {
key: fs.readFileSync(&#39;test/fixtures/keys/agent2-key.pem&#39;),
cert: fs.readFileSync(&#39;test/fixtures/keys/agent2-cert.pem&#39;)
};
https.createServer(options, function (req, res) {
res.writeHead(200);
res.end(&quot;hello world\n&quot;);
}).listen(8000);</code></pre>
<p>Or
</p>
<pre><code>var https = require(&#39;https&#39;);
var fs = require(&#39;fs&#39;);
var options = {
pfx: fs.readFileSync(&#39;server.pfx&#39;)
};
https.createServer(options, function (req, res) {
res.writeHead(200);
res.end(&quot;hello world\n&quot;);
}).listen(8000);</code></pre>
<h3>server.listen(port, [host], [backlog], [callback])<span><a class="mark" href="#all_server_listen_port_host_backlog_callback_1" id="all_server_listen_port_host_backlog_callback_1">#</a></span></h3>
<h3>server.listen(path, [callback])<span><a class="mark" href="#all_server_listen_path_callback_2" id="all_server_listen_path_callback_2">#</a></span></h3>
<h3>server.listen(handle, [callback])<span><a class="mark" href="#all_server_listen_handle_callback_2" id="all_server_listen_handle_callback_2">#</a></span></h3>
<p>See <a href="http.html#http_server_listen_port_hostname_backlog_callback">http.listen()</a> for details.
</p>
<h3>server.close([callback])<span><a class="mark" href="#all_server_close_callback_2" id="all_server_close_callback_2">#</a></span></h3>
<p>See <a href="http.html#http_server_close_callback">http.close()</a> for details.
</p>
<h2>https.request(options, callback)<span><a class="mark" href="#all_https_request_options_callback" id="all_https_request_options_callback">#</a></span></h2>
<p>Makes a request to a secure web server.
</p>
<p><code>options</code> can be an object or a string. If <code>options</code> is a string, it is
automatically parsed with <a href="url.html#url.parse">url.parse()</a>.
</p>
<p>All options from <a href="http.html#http_http_request_options_callback">http.request()</a> are valid.
</p>
<p>Example:
</p>
<pre><code>var https = require(&#39;https&#39;);
var options = {
hostname: &#39;encrypted.google.com&#39;,
port: 443,
path: &#39;/&#39;,
method: &#39;GET&#39;
};
var req = https.request(options, function(res) {
console.log(&quot;statusCode: &quot;, res.statusCode);
console.log(&quot;headers: &quot;, res.headers);
res.on(&#39;data&#39;, function(d) {
process.stdout.write(d);
});
});
req.end();
req.on(&#39;error&#39;, function(e) {
console.error(e);
});</code></pre>
<p>The options argument has the following options
</p>
<ul>
<li><code>host</code>: A domain name or IP address of the server to issue the request to.
Defaults to <code>&#39;localhost&#39;</code>.</li>
<li><code>hostname</code>: To support <code>url.parse()</code> <code>hostname</code> is preferred over <code>host</code></li>
<li><code>port</code>: Port of remote server. Defaults to 443.</li>
<li><code>method</code>: A string specifying the HTTP request method. Defaults to <code>&#39;GET&#39;</code>.</li>
<li><code>path</code>: Request path. Defaults to <code>&#39;/&#39;</code>. Should include query string if any.
E.G. <code>&#39;/index.html?page=12&#39;</code></li>
<li><code>headers</code>: An object containing request headers.</li>
<li><code>auth</code>: Basic authentication i.e. <code>&#39;user:password&#39;</code> to compute an
Authorization header.</li>
<li><code>agent</code>: Controls <a href="#https_class_https_agent">Agent</a> behavior. When an Agent is used request will
default to <code>Connection: keep-alive</code>. Possible values:<ul>
<li><code>undefined</code> (default): use <a href="#https_https_globalagent">globalAgent</a> for this host and port.</li>
<li><code>Agent</code> object: explicitly use the passed in <code>Agent</code>.</li>
<li><code>false</code>: opts out of connection pooling with an Agent, defaults request to
<code>Connection: close</code>.</li>
</ul>
</li>
</ul>
<p>The following options from <a href="tls.html#tls_tls_connect_options_callback">tls.connect()</a> can also be specified. However, a
<a href="#https_https_globalagent">globalAgent</a> silently ignores these.
</p>
<ul>
<li><code>pfx</code>: Certificate, Private key and CA certificates to use for SSL. Default <code>null</code>.</li>
<li><code>key</code>: Private key to use for SSL. Default <code>null</code>.</li>
<li><code>passphrase</code>: A string of passphrase for the private key or pfx. Default <code>null</code>.</li>
<li><code>cert</code>: Public x509 certificate to use. Default <code>null</code>.</li>
<li><code>ca</code>: An authority certificate or array of authority certificates to check
the remote host against.</li>
<li><code>ciphers</code>: A string describing the ciphers to use or exclude. Consult
<a href="http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT">http://www.openssl.org/docs/apps/ciphers.html#CIPHER_LIST_FORMAT</a> for
details on the format.</li>
<li><code>rejectUnauthorized</code>: If <code>true</code>, the server certificate is verified against
the list of supplied CAs. An <code>&#39;error&#39;</code> event is emitted if verification
fails. Verification happens at the connection level, <em>before</em> the HTTP
request is sent. Default <code>true</code>.</li>
<li><code>secureProtocol</code>: The SSL method to use, e.g. <code>SSLv3_method</code> to force
SSL version 3. The possible values depend on your installation of
OpenSSL and are defined in the constant <a href="http://www.openssl.org/docs/ssl/ssl.html#DEALING_WITH_PROTOCOL_METHODS">SSL_METHODS</a>.</li>
</ul>
<p>In order to specify these options, use a custom <code>Agent</code>.
</p>
<p>Example:
</p>
<pre><code>var options = {
hostname: &#39;encrypted.google.com&#39;,
port: 443,
path: &#39;/&#39;,
method: &#39;GET&#39;,
key: fs.readFileSync(&#39;test/fixtures/keys/agent2-key.pem&#39;),
cert: fs.readFileSync(&#39;test/fixtures/keys/agent2-cert.pem&#39;)
};
options.agent = new https.Agent(options);
var req = https.request(options, function(res) {
...
}</code></pre>
<p>Or does not use an <code>Agent</code>.
</p>
<p>Example:
</p>
<pre><code>var options = {
hostname: &#39;encrypted.google.com&#39;,
port: 443,
path: &#39;/&#39;,
method: &#39;GET&#39;,
key: fs.readFileSync(&#39;test/fixtures/keys/agent2-key.pem&#39;),
cert: fs.readFileSync(&#39;test/fixtures/keys/agent2-cert.pem&#39;),
agent: false
};
var req = https.request(options, function(res) {
...
}</code></pre>
<h2>https.get(options, callback)<span><a class="mark" href="#all_https_get_options_callback" id="all_https_get_options_callback">#</a></span></h2>
<p>Like <code>http.get()</code> but for HTTPS.
</p>
<p><code>options</code> can be an object or a string. If <code>options</code> is a string, it is
automatically parsed with <a href="url.html#url.parse">url.parse()</a>.
</p>
<p>Example:
</p>
<pre><code>var https = require(&#39;https&#39;);
https.get(&#39;https://encrypted.google.com/&#39;, function(res) {
console.log(&quot;statusCode: &quot;, res.statusCode);
console.log(&quot;headers: &quot;, res.headers);
res.on(&#39;data&#39;, function(d) {
process.stdout.write(d);
});
}).on(&#39;error&#39;, function(e) {
console.error(e);
});</code></pre>
<h2>Class: https.Agent<span><a class="mark" href="#all_class_https_agent" id="all_class_https_agent">#</a></span></h2>
<p>An Agent object for HTTPS similar to <a href="http.html#http_class_http_agent">http.Agent</a>. See <a href="#https_https_request_options_callback">https.request()</a>
for more information.
</p>
<h2>https.globalAgent<span><a class="mark" href="#all_https_globalagent" id="all_https_globalagent">#</a></span></h2>
<p>Global instance of <a href="#https_class_https_agent">https.Agent</a> for all HTTPS client requests.
</p>
<h1>URL<span><a class="mark" href="#all_url" id="all_url">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>This module has utilities for URL resolution and parsing.
Call <code>require(&#39;url&#39;)</code> to use it.
</p>
<p>Parsed URL objects have some or all of the following fields, depending on
whether or not they exist in the URL string. Any parts that are not in the URL
string will not be in the parsed object. Examples are shown for the URL
</p>
<p><code>&#39;http://user:pass@host.com:8080/p/a/t/h?query=string#hash&#39;</code>
</p>
<ul>
<li><p><code>href</code>: The full URL that was originally parsed. Both the protocol and host are lowercased.</p>
<p> Example: <code>&#39;http://user:pass@host.com:8080/p/a/t/h?query=string#hash&#39;</code></p>
</li>
<li><p><code>protocol</code>: The request protocol, lowercased.</p>
<p> Example: <code>&#39;http:&#39;</code></p>
</li>
<li><p><code>host</code>: The full lowercased host portion of the URL, including port
information.</p>
<p> Example: <code>&#39;host.com:8080&#39;</code></p>
</li>
<li><p><code>auth</code>: The authentication information portion of a URL.</p>
<p> Example: <code>&#39;user:pass&#39;</code></p>
</li>
<li><p><code>hostname</code>: Just the lowercased hostname portion of the host.</p>
<p> Example: <code>&#39;host.com&#39;</code></p>
</li>
<li><p><code>port</code>: The port number portion of the host.</p>
<p> Example: <code>&#39;8080&#39;</code></p>
</li>
<li><p><code>pathname</code>: The path section of the URL, that comes after the host and
before the query, including the initial slash if present.</p>
<p> Example: <code>&#39;/p/a/t/h&#39;</code></p>
</li>
<li><p><code>search</code>: The &#39;query string&#39; portion of the URL, including the leading
question mark.</p>
<p> Example: <code>&#39;?query=string&#39;</code></p>
</li>
<li><p><code>path</code>: Concatenation of <code>pathname</code> and <code>search</code>.</p>
<p> Example: <code>&#39;/p/a/t/h?query=string&#39;</code></p>
</li>
<li><p><code>query</code>: Either the &#39;params&#39; portion of the query string, or a
querystring-parsed object.</p>
<p> Example: <code>&#39;query=string&#39;</code> or <code>{&#39;query&#39;:&#39;string&#39;}</code></p>
</li>
<li><p><code>hash</code>: The &#39;fragment&#39; portion of the URL including the pound-sign.</p>
<p> Example: <code>&#39;#hash&#39;</code></p>
</li>
</ul>
<p>The following methods are provided by the URL module:
</p>
<h2>url.parse(urlStr, [parseQueryString], [slashesDenoteHost])<span><a class="mark" href="#all_url_parse_urlstr_parsequerystring_slashesdenotehost" id="all_url_parse_urlstr_parsequerystring_slashesdenotehost">#</a></span></h2>
<p>Take a URL string, and return an object.
</p>
<p>Pass <code>true</code> as the second argument to also parse
the query string using the <code>querystring</code> module.
Defaults to <code>false</code>.
</p>
<p>Pass <code>true</code> as the third argument to treat <code>//foo/bar</code> as
<code>{ host: &#39;foo&#39;, pathname: &#39;/bar&#39; }</code> rather than
<code>{ pathname: &#39;//foo/bar&#39; }</code>. Defaults to <code>false</code>.
</p>
<h2>url.format(urlObj)<span><a class="mark" href="#all_url_format_urlobj" id="all_url_format_urlobj">#</a></span></h2>
<p>Take a parsed URL object, and return a formatted URL string.
</p>
<ul>
<li><code>href</code> will be ignored.</li>
<li><code>protocol</code>is treated the same with or without the trailing <code>:</code> (colon).<ul>
<li>The protocols <code>http</code>, <code>https</code>, <code>ftp</code>, <code>gopher</code>, <code>file</code> will be
postfixed with <code>://</code> (colon-slash-slash).</li>
<li>All other protocols <code>mailto</code>, <code>xmpp</code>, <code>aim</code>, <code>sftp</code>, <code>foo</code>, etc will
be postfixed with <code>:</code> (colon)</li>
</ul>
</li>
<li><code>auth</code> will be used if present.</li>
<li><code>hostname</code> will only be used if <code>host</code> is absent.</li>
<li><code>port</code> will only be used if <code>host</code> is absent.</li>
<li><code>host</code> will be used in place of <code>hostname</code> and <code>port</code></li>
<li><code>pathname</code> is treated the same with or without the leading <code>/</code> (slash)</li>
<li><code>search</code> will be used in place of <code>query</code></li>
<li><code>query</code> (object; see <code>querystring</code>) will only be used if <code>search</code> is absent.</li>
<li><code>search</code> is treated the same with or without the leading <code>?</code> (question mark)</li>
<li><code>hash</code> is treated the same with or without the leading <code>#</code> (pound sign, anchor)</li>
</ul>
<h2>url.resolve(from, to)<span><a class="mark" href="#all_url_resolve_from_to" id="all_url_resolve_from_to">#</a></span></h2>
<p>Take a base URL, and a href URL, and resolve them as a browser would for
an anchor tag. Examples:
</p>
<pre><code>url.resolve(&#39;/one/two/three&#39;, &#39;four&#39;) // &#39;/one/two/four&#39;
url.resolve(&#39;http://example.com/&#39;, &#39;/one&#39;) // &#39;http://example.com/one&#39;
url.resolve(&#39;http://example.com/one&#39;, &#39;/two&#39;) // &#39;http://example.com/two&#39;</code></pre>
<h1>Query String<span><a class="mark" href="#all_query_string" id="all_query_string">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><!--name=querystring-->
<p>This module provides utilities for dealing with query strings.
It provides the following methods:
</p>
<h2>querystring.stringify(obj, [sep], [eq])<span><a class="mark" href="#all_querystring_stringify_obj_sep_eq" id="all_querystring_stringify_obj_sep_eq">#</a></span></h2>
<p>Serialize an object to a query string.
Optionally override the default separator (<code>&#39;&amp;&#39;</code>) and assignment (<code>&#39;=&#39;</code>)
characters.
</p>
<p>Example:
</p>
<pre><code>querystring.stringify({ foo: &#39;bar&#39;, baz: [&#39;qux&#39;, &#39;quux&#39;], corge: &#39;&#39; })
// returns
&#39;foo=bar&amp;baz=qux&amp;baz=quux&amp;corge=&#39;
querystring.stringify({foo: &#39;bar&#39;, baz: &#39;qux&#39;}, &#39;;&#39;, &#39;:&#39;)
// returns
&#39;foo:bar;baz:qux&#39;</code></pre>
<h2>querystring.parse(str, [sep], [eq], [options])<span><a class="mark" href="#all_querystring_parse_str_sep_eq_options" id="all_querystring_parse_str_sep_eq_options">#</a></span></h2>
<p>Deserialize a query string to an object.
Optionally override the default separator (<code>&#39;&amp;&#39;</code>) and assignment (<code>&#39;=&#39;</code>)
characters.
</p>
<p>Options object may contain <code>maxKeys</code> property (equal to 1000 by default), it&#39;ll
be used to limit processed keys. Set it to 0 to remove key count limitation.
</p>
<p>Example:
</p>
<pre><code>querystring.parse(&#39;foo=bar&amp;baz=qux&amp;baz=quux&amp;corge&#39;)
// returns
{ foo: &#39;bar&#39;, baz: [&#39;qux&#39;, &#39;quux&#39;], corge: &#39;&#39; }</code></pre>
<h2>querystring.escape<span><a class="mark" href="#all_querystring_escape" id="all_querystring_escape">#</a></span></h2>
<p>The escape function used by <code>querystring.stringify</code>,
provided so that it could be overridden if necessary.
</p>
<h2>querystring.unescape<span><a class="mark" href="#all_querystring_unescape" id="all_querystring_unescape">#</a></span></h2>
<p>The unescape function used by <code>querystring.parse</code>,
provided so that it could be overridden if necessary.
</p>
<h1>punycode<span><a class="mark" href="#all_punycode" id="all_punycode">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable</pre><p><a href="http://mths.be/punycode">Punycode.js</a> is bundled with Node.js v0.6.2+. Use
<code>require(&#39;punycode&#39;)</code> to access it. (To use it with other Node.js versions,
use npm to install the <code>punycode</code> module first.)
</p>
<h2>punycode.decode(string)<span><a class="mark" href="#all_punycode_decode_string" id="all_punycode_decode_string">#</a></span></h2>
<p>Converts a Punycode string of ASCII code points to a string of Unicode code
points.
</p>
<pre><code>// decode domain name parts
punycode.decode(&#39;maana-pta&#39;); // &#39;mañana&#39;
punycode.decode(&#39;--dqo34k&#39;); // &#39;☃-⌘&#39;</code></pre>
<h2>punycode.encode(string)<span><a class="mark" href="#all_punycode_encode_string" id="all_punycode_encode_string">#</a></span></h2>
<p>Converts a string of Unicode code points to a Punycode string of ASCII code
points.
</p>
<pre><code>// encode domain name parts
punycode.encode(&#39;mañana&#39;); // &#39;maana-pta&#39;
punycode.encode(&#39;☃-⌘&#39;); // &#39;--dqo34k&#39;</code></pre>
<h2>punycode.toUnicode(domain)<span><a class="mark" href="#all_punycode_tounicode_domain" id="all_punycode_tounicode_domain">#</a></span></h2>
<p>Converts a Punycode string representing a domain name to Unicode. Only the
Punycoded parts of the domain name will be converted, i.e. it doesn&#39;t matter if
you call it on a string that has already been converted to Unicode.
</p>
<pre><code>// decode domain names
punycode.toUnicode(&#39;xn--maana-pta.com&#39;); // &#39;mañana.com&#39;
punycode.toUnicode(&#39;xn----dqo34k.com&#39;); // &#39;☃-⌘.com&#39;</code></pre>
<h2>punycode.toASCII(domain)<span><a class="mark" href="#all_punycode_toascii_domain" id="all_punycode_toascii_domain">#</a></span></h2>
<p>Converts a Unicode string representing a domain name to Punycode. Only the
non-ASCII parts of the domain name will be converted, i.e. it doesn&#39;t matter if
you call it with a domain that&#39;s already in ASCII.
</p>
<pre><code>// encode domain names
punycode.toASCII(&#39;mañana.com&#39;); // &#39;xn--maana-pta.com&#39;
punycode.toASCII(&#39;☃-⌘.com&#39;); // &#39;xn----dqo34k.com&#39;</code></pre>
<h2>punycode.ucs2<span><a class="mark" href="#all_punycode_ucs2" id="all_punycode_ucs2">#</a></span></h2>
<h3>punycode.ucs2.decode(string)<span><a class="mark" href="#all_punycode_ucs2_decode_string" id="all_punycode_ucs2_decode_string">#</a></span></h3>
<p>Creates an array containing the decimal code points of each Unicode character
in the string. While <a href="http://mathiasbynens.be/notes/javascript-encoding">JavaScript uses UCS-2
internally</a>, this function
will convert a pair of surrogate halves (each of which UCS-2 exposes as
separate characters) into a single code point, matching UTF-16.
</p>
<pre><code>punycode.ucs2.decode(&#39;abc&#39;); // [97, 98, 99]
// surrogate pair for U+1D306 tetragram for centre:
punycode.ucs2.decode(&#39;\uD834\uDF06&#39;); // [0x1D306]</code></pre>
<h3>punycode.ucs2.encode(codePoints)<span><a class="mark" href="#all_punycode_ucs2_encode_codepoints" id="all_punycode_ucs2_encode_codepoints">#</a></span></h3>
<p>Creates a string based on an array of decimal code points.
</p>
<pre><code>punycode.ucs2.encode([97, 98, 99]); // &#39;abc&#39;
punycode.ucs2.encode([0x1D306]); // &#39;\uD834\uDF06&#39;</code></pre>
<h2>punycode.version<span><a class="mark" href="#all_punycode_version" id="all_punycode_version">#</a></span></h2>
<p>A string representing the current Punycode.js version number.
</p>
<h1>Readline<span><a class="mark" href="#all_readline" id="all_readline">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable</pre><p>To use this module, do <code>require(&#39;readline&#39;)</code>. Readline allows reading of a
stream (such as <code>process.stdin</code>) on a line-by-line basis.
</p>
<p>Note that once you&#39;ve invoked this module, your node program will not
terminate until you&#39;ve closed the interface. Here&#39;s how to allow your
program to gracefully exit:
</p>
<pre><code>var readline = require(&#39;readline&#39;);
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
rl.question(&quot;What do you think of node.js? &quot;, function(answer) {
// TODO: Log the answer in a database
console.log(&quot;Thank you for your valuable feedback:&quot;, answer);
rl.close();
});</code></pre>
<h2>readline.createInterface(options)<span><a class="mark" href="#all_readline_createinterface_options" id="all_readline_createinterface_options">#</a></span></h2>
<p>Creates a readline <code>Interface</code> instance. Accepts an &quot;options&quot; Object that takes
the following values:
</p>
<ul>
<li><p><code>input</code> - the readable stream to listen to (Required).</p>
</li>
<li><p><code>output</code> - the writable stream to write readline data to (Required).</p>
</li>
<li><p><code>completer</code> - an optional function that is used for Tab autocompletion. See
below for an example of using this.</p>
</li>
<li><p><code>terminal</code> - pass <code>true</code> if the <code>input</code> and <code>output</code> streams should be
treated like a TTY, and have ANSI/VT100 escape codes written to it.
Defaults to checking <code>isTTY</code> on the <code>output</code> stream upon instantiation.</p>
</li>
</ul>
<p>The <code>completer</code> function is given a the current line entered by the user, and
is supposed to return an Array with 2 entries:
</p>
<ol>
<li><p>An Array with matching entries for the completion.</p>
</li>
<li><p>The substring that was used for the matching.</p>
</li>
</ol>
<p>Which ends up looking something like:
<code>[[substr1, substr2, ...], originalsubstring]</code>.
</p>
<p>Example:
</p>
<pre><code>function completer(line) {
var completions = &#39;.help .error .exit .quit .q&#39;.split(&#39; &#39;)
var hits = completions.filter(function(c) { return c.indexOf(line) == 0 })
// show all completions if none found
return [hits.length ? hits : completions, line]
}</code></pre>
<p>Also <code>completer</code> can be run in async mode if it accepts two arguments:
</p>
<pre><code>function completer(linePartial, callback) {
callback(null, [[&#39;123&#39;], linePartial]);
}</code></pre>
<p><code>createInterface</code> is commonly used with <code>process.stdin</code> and
<code>process.stdout</code> in order to accept user input:
</p>
<pre><code>var readline = require(&#39;readline&#39;);
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});</code></pre>
<p>Once you have a readline instance, you most commonly listen for the
<code>&quot;line&quot;</code> event.
</p>
<p>If <code>terminal</code> is <code>true</code> for this instance then the <code>output</code> stream will get
the best compatibility if it defines an <code>output.columns</code> property, and fires
a <code>&quot;resize&quot;</code> event on the <code>output</code> if/when the columns ever change
(<code>process.stdout</code> does this automatically when it is a TTY).
</p>
<h2>Class: Interface<span><a class="mark" href="#all_class_interface" id="all_class_interface">#</a></span></h2>
<p>The class that represents a readline interface with an input and output
stream.
</p>
<h3>rl.setPrompt(prompt, length)<span><a class="mark" href="#all_rl_setprompt_prompt_length" id="all_rl_setprompt_prompt_length">#</a></span></h3>
<p>Sets the prompt, for example when you run <code>node</code> on the command line, you see
<code>&gt; </code>, which is node&#39;s prompt.
</p>
<h3>rl.prompt([preserveCursor])<span><a class="mark" href="#all_rl_prompt_preservecursor" id="all_rl_prompt_preservecursor">#</a></span></h3>
<p>Readies readline for input from the user, putting the current <code>setPrompt</code>
options on a new line, giving the user a new spot to write. Set <code>preserveCursor</code>
to <code>true</code> to prevent the cursor placement being reset to <code>0</code>.
</p>
<p>This will also resume the <code>input</code> stream used with <code>createInterface</code> if it has
been paused.
</p>
<h3>rl.question(query, callback)<span><a class="mark" href="#all_rl_question_query_callback" id="all_rl_question_query_callback">#</a></span></h3>
<p>Prepends the prompt with <code>query</code> and invokes <code>callback</code> with the user&#39;s
response. Displays the query to the user, and then invokes <code>callback</code>
with the user&#39;s response after it has been typed.
</p>
<p>This will also resume the <code>input</code> stream used with <code>createInterface</code> if
it has been paused.
</p>
<p>Example usage:
</p>
<pre><code>interface.question(&#39;What is your favorite food?&#39;, function(answer) {
console.log(&#39;Oh, so your favorite food is &#39; + answer);
});</code></pre>
<h3>rl.pause()<span><a class="mark" href="#all_rl_pause" id="all_rl_pause">#</a></span></h3>
<p>Pauses the readline <code>input</code> stream, allowing it to be resumed later if needed.
</p>
<h3>rl.resume()<span><a class="mark" href="#all_rl_resume" id="all_rl_resume">#</a></span></h3>
<p>Resumes the readline <code>input</code> stream.
</p>
<h3>rl.close()<span><a class="mark" href="#all_rl_close" id="all_rl_close">#</a></span></h3>
<p>Closes the <code>Interface</code> instance, relinquishing control on the <code>input</code> and
<code>output</code> streams. The &quot;close&quot; event will also be emitted.
</p>
<h3>rl.write(data, [key])<span><a class="mark" href="#all_rl_write_data_key" id="all_rl_write_data_key">#</a></span></h3>
<p>Writes <code>data</code> to <code>output</code> stream. <code>key</code> is an object literal to represent a key
sequence; available if the terminal is a TTY.
</p>
<p>This will also resume the <code>input</code> stream if it has been paused.
</p>
<p>Example:
</p>
<pre><code>rl.write(&#39;Delete me!&#39;);
// Simulate ctrl+u to delete the line written previously
rl.write(null, {ctrl: true, name: &#39;u&#39;});</code></pre>
<h2>Events<span><a class="mark" href="#all_events_1" id="all_events_1">#</a></span></h2>
<h3>Event: &#39;line&#39;<span><a class="mark" href="#all_event_line" id="all_event_line">#</a></span></h3>
<p><code>function (line) {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream receives a <code>\n</code>, usually received when the
user hits enter, or return. This is a good hook to listen for user input.
</p>
<p>Example of listening for <code>line</code>:
</p>
<pre><code>rl.on(&#39;line&#39;, function (cmd) {
console.log(&#39;You just typed: &#39;+cmd);
});</code></pre>
<h3>Event: &#39;pause&#39;<span><a class="mark" href="#all_event_pause" id="all_event_pause">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream is paused.
</p>
<p>Also emitted whenever the <code>input</code> stream is not paused and receives the
<code>SIGCONT</code> event. (See events <code>SIGTSTP</code> and <code>SIGCONT</code>)
</p>
<p>Example of listening for <code>pause</code>:
</p>
<pre><code>rl.on(&#39;pause&#39;, function() {
console.log(&#39;Readline paused.&#39;);
});</code></pre>
<h3>Event: &#39;resume&#39;<span><a class="mark" href="#all_event_resume" id="all_event_resume">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream is resumed.
</p>
<p>Example of listening for <code>resume</code>:
</p>
<pre><code>rl.on(&#39;resume&#39;, function() {
console.log(&#39;Readline resumed.&#39;);
});</code></pre>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_7" id="all_event_close_7">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted when <code>close()</code> is called.
</p>
<p>Also emitted when the <code>input</code> stream receives its &quot;end&quot; event. The <code>Interface</code>
instance should be considered &quot;finished&quot; once this is emitted. For example, when
the <code>input</code> stream receives <code>^D</code>, respectively known as <code>EOT</code>.
</p>
<p>This event is also called if there is no <code>SIGINT</code> event listener present when
the <code>input</code> stream receives a <code>^C</code>, respectively known as <code>SIGINT</code>.
</p>
<h3>Event: &#39;SIGINT&#39;<span><a class="mark" href="#all_event_sigint" id="all_event_sigint">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted whenever the <code>input</code> stream receives a <code>^C</code>, respectively known as
<code>SIGINT</code>. If there is no <code>SIGINT</code> event listener present when the <code>input</code>
stream receives a <code>SIGINT</code>, <code>pause</code> will be triggered.
</p>
<p>Example of listening for <code>SIGINT</code>:
</p>
<pre><code>rl.on(&#39;SIGINT&#39;, function() {
rl.question(&#39;Are you sure you want to exit?&#39;, function(answer) {
if (answer.match(/^y(es)?$/i)) rl.pause();
});
});</code></pre>
<h3>Event: &#39;SIGTSTP&#39;<span><a class="mark" href="#all_event_sigtstp" id="all_event_sigtstp">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p><strong>This does not work on Windows.</strong>
</p>
<p>Emitted whenever the <code>input</code> stream receives a <code>^Z</code>, respectively known as
<code>SIGTSTP</code>. If there is no <code>SIGTSTP</code> event listener present when the <code>input</code>
stream receives a <code>SIGTSTP</code>, the program will be sent to the background.
</p>
<p>When the program is resumed with <code>fg</code>, the <code>pause</code> and <code>SIGCONT</code> events will be
emitted. You can use either to resume the stream.
</p>
<p>The <code>pause</code> and <code>SIGCONT</code> events will not be triggered if the stream was paused
before the program was sent to the background.
</p>
<p>Example of listening for <code>SIGTSTP</code>:
</p>
<pre><code>rl.on(&#39;SIGTSTP&#39;, function() {
// This will override SIGTSTP and prevent the program from going to the
// background.
console.log(&#39;Caught SIGTSTP.&#39;);
});</code></pre>
<h3>Event: &#39;SIGCONT&#39;<span><a class="mark" href="#all_event_sigcont" id="all_event_sigcont">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p><strong>This does not work on Windows.</strong>
</p>
<p>Emitted whenever the <code>input</code> stream is sent to the background with <code>^Z</code>,
respectively known as <code>SIGTSTP</code>, and then continued with <code>fg(1)</code>. This event
only emits if the stream was not paused before sending the program to the
background.
</p>
<p>Example of listening for <code>SIGCONT</code>:
</p>
<pre><code>rl.on(&#39;SIGCONT&#39;, function() {
// `prompt` will automatically resume the stream
rl.prompt();
});</code></pre>
<h2>Example: Tiny CLI<span><a class="mark" href="#all_example_tiny_cli" id="all_example_tiny_cli">#</a></span></h2>
<p>Here&#39;s an example of how to use all these together to craft a tiny command
line interface:
</p>
<pre><code>var readline = require(&#39;readline&#39;),
rl = readline.createInterface(process.stdin, process.stdout);
rl.setPrompt(&#39;OHAI&gt; &#39;);
rl.prompt();
rl.on(&#39;line&#39;, function(line) {
switch(line.trim()) {
case &#39;hello&#39;:
console.log(&#39;world!&#39;);
break;
default:
console.log(&#39;Say what? I might have heard `&#39; + line.trim() + &#39;`&#39;);
break;
}
rl.prompt();
}).on(&#39;close&#39;, function() {
console.log(&#39;Have a great day!&#39;);
process.exit(0);
});</code></pre>
<h1>REPL<span><a class="mark" href="#all_repl" id="all_repl">#</a></span></h1>
<p>A Read-Eval-Print-Loop (REPL) is available both as a standalone program and
easily includable in other programs. The REPL provides a way to interactively
run JavaScript and see the results. It can be used for debugging, testing, or
just trying things out.
</p>
<p>By executing <code>node</code> without any arguments from the command-line you will be
dropped into the REPL. It has simplistic emacs line-editing.
</p>
<pre><code>mjr:~$ node
Type &#39;.help&#39; for options.
&gt; a = [ 1, 2, 3];
[ 1, 2, 3 ]
&gt; a.forEach(function (v) {
... console.log(v);
... });
1
2
3</code></pre>
<p>For advanced line-editors, start node with the environmental variable
<code>NODE_NO_READLINE=1</code>. This will start the main and debugger REPL in canonical
terminal settings which will allow you to use with <code>rlwrap</code>.
</p>
<p>For example, you could add this to your bashrc file:
</p>
<pre><code>alias node=&quot;env NODE_NO_READLINE=1 rlwrap node&quot;</code></pre>
<h2>repl.start(options)<span><a class="mark" href="#all_repl_start_options" id="all_repl_start_options">#</a></span></h2>
<p>Returns and starts a <code>REPLServer</code> instance. Accepts an &quot;options&quot; Object that
takes the following values:
</p>
<ul>
<li><p><code>prompt</code> - the prompt and <code>stream</code> for all I/O. Defaults to <code>&gt; </code>.</p>
</li>
<li><p><code>input</code> - the readable stream to listen to. Defaults to <code>process.stdin</code>.</p>
</li>
<li><p><code>output</code> - the writable stream to write readline data to. Defaults to
<code>process.stdout</code>.</p>
</li>
<li><p><code>terminal</code> - pass <code>true</code> if the <code>stream</code> should be treated like a TTY, and
have ANSI/VT100 escape codes written to it. Defaults to checking <code>isTTY</code>
on the <code>output</code> stream upon instantiation.</p>
</li>
<li><p><code>eval</code> - function that will be used to eval each given line. Defaults to
an async wrapper for <code>eval()</code>. See below for an example of a custom <code>eval</code>.</p>
</li>
<li><p><code>useColors</code> - a boolean which specifies whether or not the <code>writer</code> function
should output colors. If a different <code>writer</code> function is set then this does
nothing. Defaults to the repl&#39;s <code>terminal</code> value.</p>
</li>
<li><p><code>useGlobal</code> - if set to <code>true</code>, then the repl will use the <code>global</code> object,
instead of running scripts in a separate context. Defaults to <code>false</code>.</p>
</li>
<li><p><code>ignoreUndefined</code> - if set to <code>true</code>, then the repl will not output the
return value of command if it&#39;s <code>undefined</code>. Defaults to <code>false</code>.</p>
</li>
<li><p><code>writer</code> - the function to invoke for each command that gets evaluated which
returns the formatting (including coloring) to display. Defaults to
<code>util.inspect</code>.</p>
</li>
</ul>
<p>You can use your own <code>eval</code> function if it has following signature:
</p>
<pre><code>function eval(cmd, context, filename, callback) {
callback(null, result);
}</code></pre>
<p>Multiple REPLs may be started against the same running instance of node. Each
will share the same global object but will have unique I/O.
</p>
<p>Here is an example that starts a REPL on stdin, a Unix socket, and a TCP socket:
</p>
<pre><code>var net = require(&quot;net&quot;),
repl = require(&quot;repl&quot;);
connections = 0;
repl.start({
prompt: &quot;node via stdin&gt; &quot;,
input: process.stdin,
output: process.stdout
});
net.createServer(function (socket) {
connections += 1;
repl.start({
prompt: &quot;node via Unix socket&gt; &quot;,
input: socket,
output: socket
}).on(&#39;exit&#39;, function() {
socket.end();
})
}).listen(&quot;/tmp/node-repl-sock&quot;);
net.createServer(function (socket) {
connections += 1;
repl.start({
prompt: &quot;node via TCP socket&gt; &quot;,
input: socket,
output: socket
}).on(&#39;exit&#39;, function() {
socket.end();
});
}).listen(5001);</code></pre>
<p>Running this program from the command line will start a REPL on stdin. Other
REPL clients may connect through the Unix socket or TCP socket. <code>telnet</code> is useful
for connecting to TCP sockets, and <code>socat</code> can be used to connect to both Unix and
TCP sockets.
</p>
<p>By starting a REPL from a Unix socket-based server instead of stdin, you can
connect to a long-running node process without restarting it.
</p>
<p>For an example of running a &quot;full-featured&quot; (<code>terminal</code>) REPL over
a <code>net.Server</code> and <code>net.Socket</code> instance, see: <a href="https://gist.github.com/2209310">https://gist.github.com/2209310</a>
</p>
<p>For an example of running a REPL instance over <code>curl(1)</code>,
see: <a href="https://gist.github.com/2053342">https://gist.github.com/2053342</a>
</p>
<h3>Event: &#39;exit&#39;<span><a class="mark" href="#all_event_exit_1" id="all_event_exit_1">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted when the user exits the REPL in any of the defined ways. Namely, typing
<code>.exit</code> at the repl, pressing Ctrl+C twice to signal SIGINT, or pressing Ctrl+D
to signal &quot;end&quot; on the <code>input</code> stream.
</p>
<p>Example of listening for <code>exit</code>:
</p>
<pre><code>r.on(&#39;exit&#39;, function () {
console.log(&#39;Got &quot;exit&quot; event from repl!&#39;);
process.exit();
});</code></pre>
<h2>REPL Features<span><a class="mark" href="#all_repl_features" id="all_repl_features">#</a></span></h2>
<!-- type=misc -->
<p>Inside the REPL, Control+D will exit. Multi-line expressions can be input.
Tab completion is supported for both global and local variables.
</p>
<p>The special variable <code>_</code> (underscore) contains the result of the last expression.
</p>
<pre><code>&gt; [ &quot;a&quot;, &quot;b&quot;, &quot;c&quot; ]
[ &#39;a&#39;, &#39;b&#39;, &#39;c&#39; ]
&gt; _.length
3
&gt; _ += 1
4</code></pre>
<p>The REPL provides access to any variables in the global scope. You can expose
a variable to the REPL explicitly by assigning it to the <code>context</code> object
associated with each <code>REPLServer</code>. For example:
</p>
<pre><code>// repl_test.js
var repl = require(&quot;repl&quot;),
msg = &quot;message&quot;;
repl.start(&quot;&gt; &quot;).context.m = msg;</code></pre>
<p>Things in the <code>context</code> object appear as local within the REPL:
</p>
<pre><code>mjr:~$ node repl_test.js
&gt; m
&#39;message&#39;</code></pre>
<p>There are a few special REPL commands:
</p>
<ul>
<li><code>.break</code> - While inputting a multi-line expression, sometimes you get lost
or just don&#39;t care about completing it. <code>.break</code> will start over.</li>
<li><code>.clear</code> - Resets the <code>context</code> object to an empty object and clears any
multi-line expression.</li>
<li><code>.exit</code> - Close the I/O stream, which will cause the REPL to exit.</li>
<li><code>.help</code> - Show this list of special commands.</li>
<li><code>.save</code> - Save the current REPL session to a file<blockquote>
<p>.save ./file/to/save.js</p>
</blockquote>
</li>
<li><code>.load</code> - Load a file into the current REPL session.<blockquote>
<p>.load ./file/to/load.js</p>
</blockquote>
</li>
</ul>
<p>The following key combinations in the REPL have these special effects:
</p>
<ul>
<li><code>&lt;ctrl&gt;C</code> - Similar to the <code>.break</code> keyword. Terminates the current
command. Press twice on a blank line to forcibly exit.</li>
<li><code>&lt;ctrl&gt;D</code> - Similar to the <code>.exit</code> keyword.</li>
</ul>
<h1>Executing JavaScript<span><a class="mark" href="#all_executing_javascript" id="all_executing_javascript">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable. See Caveats, below.</pre><!--name=vm-->
<p>You can access this module with:
</p>
<pre><code>var vm = require(&#39;vm&#39;);</code></pre>
<p>JavaScript code can be compiled and run immediately or compiled, saved, and run later.
</p>
<h2>Caveats<span><a class="mark" href="#all_caveats_1" id="all_caveats_1">#</a></span></h2>
<p>The <code>vm</code> module has many known issues and edge cases. If you run into
issues or unexpected behavior, please consult <a href="https://github.com/joyent/node/issues?labels=vm&amp;state=open">the open issues on
GitHub</a>.
Some of the biggest problems are described below.
</p>
<h3>Sandboxes<span><a class="mark" href="#all_sandboxes" id="all_sandboxes">#</a></span></h3>
<p>The <code>sandbox</code> argument to <code>vm.runInNewContext</code> and <code>vm.createContext</code>,
along with the <code>initSandbox</code> argument to <code>vm.createContext</code>, do not
behave as one might normally expect and their behavior varies
between different versions of Node.
</p>
<p>The key issue to be aware of is that V8 provides no way to directly
control the global object used within a context. As a result, while
properties of your <code>sandbox</code> object will be available in the context,
any properties from the <code>prototype</code>s of the <code>sandbox</code> may not be
available. Furthermore, the <code>this</code> expression within the global scope
of the context evaluates to the empty object (<code>{}</code>) instead of to
your sandbox.
</p>
<p>Your sandbox&#39;s properties are also not shared directly with the script.
Instead, the properties of the sandbox are copied into the context at
the beginning of execution, and then after execution, the properties
are copied back out in an attempt to propagate any changes.
</p>
<h3>Globals<span><a class="mark" href="#all_globals" id="all_globals">#</a></span></h3>
<p>Properties of the global object, like <code>Array</code> and <code>String</code>, have
different values inside of a context. This means that common
expressions like <code>[] instanceof Array</code> or
<code>Object.getPrototypeOf([]) === Array.prototype</code> may not produce
expected results when used inside of scripts evaluated via the <code>vm</code> module.
</p>
<p>Some of these problems have known workarounds listed in the issues for
<code>vm</code> on GitHub. for example, <code>Array.isArray</code> works around
the example problem with <code>Array</code>.
</p>
<h2>vm.runInThisContext(code, [filename])<span><a class="mark" href="#all_vm_runinthiscontext_code_filename" id="all_vm_runinthiscontext_code_filename">#</a></span></h2>
<p><code>vm.runInThisContext()</code> compiles <code>code</code>, runs it and returns the result. Running
code does not have access to local scope. <code>filename</code> is optional, it&#39;s used only
in stack traces.
</p>
<p>Example of using <code>vm.runInThisContext</code> and <code>eval</code> to run the same code:
</p>
<pre><code>var localVar = 123,
usingscript, evaled,
vm = require(&#39;vm&#39;);
usingscript = vm.runInThisContext(&#39;localVar = 1;&#39;,
&#39;myfile.vm&#39;);
console.log(&#39;localVar: &#39; + localVar + &#39;, usingscript: &#39; +
usingscript);
evaled = eval(&#39;localVar = 1;&#39;);
console.log(&#39;localVar: &#39; + localVar + &#39;, evaled: &#39; +
evaled);
// localVar: 123, usingscript: 1
// localVar: 1, evaled: 1</code></pre>
<p><code>vm.runInThisContext</code> does not have access to the local scope, so <code>localVar</code> is unchanged.
<code>eval</code> does have access to the local scope, so <code>localVar</code> is changed.
</p>
<p>In case of syntax error in <code>code</code>, <code>vm.runInThisContext</code> emits the syntax error to stderr
and throws an exception.
</p>
<h2>vm.runInNewContext(code, [sandbox], [filename])<span><a class="mark" href="#all_vm_runinnewcontext_code_sandbox_filename" id="all_vm_runinnewcontext_code_sandbox_filename">#</a></span></h2>
<p><code>vm.runInNewContext</code> compiles <code>code</code>, then runs it in <code>sandbox</code> and returns the
result. Running code does not have access to local scope. The object <code>sandbox</code>
will be used as the global object for <code>code</code>.
<code>sandbox</code> and <code>filename</code> are optional, <code>filename</code> is only used in stack traces.
</p>
<p>Example: compile and execute code that increments a global variable and sets a new one.
These globals are contained in the sandbox.
</p>
<pre><code>var util = require(&#39;util&#39;),
vm = require(&#39;vm&#39;),
sandbox = {
animal: &#39;cat&#39;,
count: 2
};
vm.runInNewContext(&#39;count += 1; name = &quot;kitty&quot;&#39;, sandbox, &#39;myfile.vm&#39;);
console.log(util.inspect(sandbox));
// { animal: &#39;cat&#39;, count: 3, name: &#39;kitty&#39; }</code></pre>
<p>Note that running untrusted code is a tricky business requiring great care. To prevent accidental
global variable leakage, <code>vm.runInNewContext</code> is quite useful, but safely running untrusted code
requires a separate process.
</p>
<p>In case of syntax error in <code>code</code>, <code>vm.runInNewContext</code> emits the syntax error to stderr
and throws an exception.
</p>
<h2>vm.runInContext(code, context, [filename])<span><a class="mark" href="#all_vm_runincontext_code_context_filename" id="all_vm_runincontext_code_context_filename">#</a></span></h2>
<p><code>vm.runInContext</code> compiles <code>code</code>, then runs it in <code>context</code> and returns the
result. A (V8) context comprises a global object, together with a set of
built-in objects and functions. Running code does not have access to local scope
and the global object held within <code>context</code> will be used as the global object
for <code>code</code>.
<code>filename</code> is optional, it&#39;s used only in stack traces.
</p>
<p>Example: compile and execute code in a existing context.
</p>
<pre><code>var util = require(&#39;util&#39;),
vm = require(&#39;vm&#39;),
initSandbox = {
animal: &#39;cat&#39;,
count: 2
},
context = vm.createContext(initSandbox);
vm.runInContext(&#39;count += 1; name = &quot;CATT&quot;&#39;, context, &#39;myfile.vm&#39;);
console.log(util.inspect(context));
// { animal: &#39;cat&#39;, count: 3, name: &#39;CATT&#39; }</code></pre>
<p>Note that <code>createContext</code> will perform a shallow clone of the supplied sandbox object in order to
initialize the global object of the freshly constructed context.
</p>
<p>Note that running untrusted code is a tricky business requiring great care. To prevent accidental
global variable leakage, <code>vm.runInContext</code> is quite useful, but safely running untrusted code
requires a separate process.
</p>
<p>In case of syntax error in <code>code</code>, <code>vm.runInContext</code> emits the syntax error to stderr
and throws an exception.
</p>
<h2>vm.createContext([initSandbox])<span><a class="mark" href="#all_vm_createcontext_initsandbox" id="all_vm_createcontext_initsandbox">#</a></span></h2>
<p><code>vm.createContext</code> creates a new context which is suitable for use as the 2nd argument of a subsequent
call to <code>vm.runInContext</code>. A (V8) context comprises a global object together with a set of
build-in objects and functions. The optional argument <code>initSandbox</code> will be shallow-copied
to seed the initial contents of the global object used by the context.
</p>
<h2>vm.createScript(code, [filename])<span><a class="mark" href="#all_vm_createscript_code_filename" id="all_vm_createscript_code_filename">#</a></span></h2>
<p><code>createScript</code> compiles <code>code</code> but does not run it. Instead, it returns a
<code>vm.Script</code> object representing this compiled code. This script can be run
later many times using methods below. The returned script is not bound to any
global object. It is bound before each run, just for that run. <code>filename</code> is
optional, it&#39;s only used in stack traces.
</p>
<p>In case of syntax error in <code>code</code>, <code>createScript</code> prints the syntax error to stderr
and throws an exception.
</p>
<h2>Class: Script<span><a class="mark" href="#all_class_script" id="all_class_script">#</a></span></h2>
<p>A class for running scripts. Returned by vm.createScript.
</p>
<h3>script.runInThisContext()<span><a class="mark" href="#all_script_runinthiscontext" id="all_script_runinthiscontext">#</a></span></h3>
<p>Similar to <code>vm.runInThisContext</code> but a method of a precompiled <code>Script</code> object.
<code>script.runInThisContext</code> runs the code of <code>script</code> and returns the result.
Running code does not have access to local scope, but does have access to the <code>global</code> object
(v8: in actual context).
</p>
<p>Example of using <code>script.runInThisContext</code> to compile code once and run it multiple times:
</p>
<pre><code>var vm = require(&#39;vm&#39;);
globalVar = 0;
var script = vm.createScript(&#39;globalVar += 1&#39;, &#39;myfile.vm&#39;);
for (var i = 0; i &lt; 1000 ; i += 1) {
script.runInThisContext();
}
console.log(globalVar);
// 1000</code></pre>
<h3>script.runInNewContext([sandbox])<span><a class="mark" href="#all_script_runinnewcontext_sandbox" id="all_script_runinnewcontext_sandbox">#</a></span></h3>
<p>Similar to <code>vm.runInNewContext</code> a method of a precompiled <code>Script</code> object.
<code>script.runInNewContext</code> runs the code of <code>script</code> with <code>sandbox</code> as the global object and returns the result.
Running code does not have access to local scope. <code>sandbox</code> is optional.
</p>
<p>Example: compile code that increments a global variable and sets one, then execute this code multiple times.
These globals are contained in the sandbox.
</p>
<pre><code>var util = require(&#39;util&#39;),
vm = require(&#39;vm&#39;),
sandbox = {
animal: &#39;cat&#39;,
count: 2
};
var script = vm.createScript(&#39;count += 1; name = &quot;kitty&quot;&#39;, &#39;myfile.vm&#39;);
for (var i = 0; i &lt; 10 ; i += 1) {
script.runInNewContext(sandbox);
}
console.log(util.inspect(sandbox));
// { animal: &#39;cat&#39;, count: 12, name: &#39;kitty&#39; }</code></pre>
<p>Note that running untrusted code is a tricky business requiring great care. To prevent accidental
global variable leakage, <code>script.runInNewContext</code> is quite useful, but safely running untrusted code
requires a separate process.
</p>
<h1>Child Process<span><a class="mark" href="#all_child_process" id="all_child_process">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>Node provides a tri-directional <code>popen(3)</code> facility through the
<code>child_process</code> module.
</p>
<p>It is possible to stream data through a child&#39;s <code>stdin</code>, <code>stdout</code>, and
<code>stderr</code> in a fully non-blocking way. (Note that some programs use
line-buffered I/O internally. That doesn&#39;t affect node.js but it means
data you send to the child process is not immediately consumed.)
</p>
<p>To create a child process use <code>require(&#39;child_process&#39;).spawn()</code> or
<code>require(&#39;child_process&#39;).fork()</code>. The semantics of each are slightly
different, and explained below.
</p>
<h2>Class: ChildProcess<span><a class="mark" href="#all_class_childprocess" id="all_class_childprocess">#</a></span></h2>
<p><code>ChildProcess</code> is an <a href="events.html#events_class_events_eventemitter">EventEmitter</a>.
</p>
<p>Child processes always have three streams associated with them. <code>child.stdin</code>,
<code>child.stdout</code>, and <code>child.stderr</code>. These may be shared with the stdio
streams of the parent process, or they may be separate stream objects
which can be piped to and from.
</p>
<p>The ChildProcess class is not intended to be used directly. Use the
<code>spawn()</code> or <code>fork()</code> methods to create a Child Process instance.
</p>
<h3>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_6" id="all_event_error_6">#</a></span></h3>
<div class="signature"><ul>
<li><code>err</code> <span class="type">Error Object</span> the error.</li>
</div></ul>
<p>Emitted when:
</p>
<ol>
<li>The process could not be spawned, or</li>
<li>The process could not be killed, or</li>
<li>Sending a message to the child process failed for whatever reason.</li>
</ol>
<p>Note that the <code>exit</code>-event may or may not fire after an error has occured. If
you are listening on both events to fire a function, remember to guard against
calling your function twice.
</p>
<p>See also <a href="#child_process_child_kill_signal"><code>ChildProcess#kill()</code></a> and
<a href="#child_process_child_send_message_sendhandle"><code>ChildProcess#send()</code></a>.
</p>
<h3>Event: &#39;exit&#39;<span><a class="mark" href="#all_event_exit_2" id="all_event_exit_2">#</a></span></h3>
<div class="signature"><ul>
<li><code>code</code> <span class="type">Number</span> the exit code, if it exited normally.</li>
<li><code>signal</code> <span class="type">String</span> the signal passed to kill the child process, if it
was killed by the parent.</li>
</div></ul>
<p>This event is emitted after the child process ends. If the process terminated
normally, <code>code</code> is the final exit code of the process, otherwise <code>null</code>. If
the process terminated due to receipt of a signal, <code>signal</code> is the string name
of the signal, otherwise <code>null</code>.
</p>
<p>Note that the child process stdio streams might still be open.
</p>
<p>Also, note that node establishes signal handlers for <code>&#39;SIGINT&#39;</code> and <code>&#39;SIGTERM</code>&#39;,
so it will not terminate due to receipt of those signals, it will exit.
</p>
<p>See <code>waitpid(2)</code>.
</p>
<h3>Event: &#39;close&#39;<span><a class="mark" href="#all_event_close_8" id="all_event_close_8">#</a></span></h3>
<div class="signature"><ul>
<li><code>code</code> <span class="type">Number</span> the exit code, if it exited normally.</li>
<li><code>signal</code> <span class="type">String</span> the signal passed to kill the child process, if it
was killed by the parent.</li>
</div></ul>
<p>This event is emitted when the stdio streams of a child process have all
terminated. This is distinct from &#39;exit&#39;, since multiple processes
might share the same stdio streams.
</p>
<h3>Event: &#39;disconnect&#39;<span><a class="mark" href="#all_event_disconnect" id="all_event_disconnect">#</a></span></h3>
<p>This event is emitted after calling the <code>.disconnect()</code> method in the parent
or in the child. After disconnecting it is no longer possible to send messages,
and the <code>.connected</code> property is false.
</p>
<h3>Event: &#39;message&#39;<span><a class="mark" href="#all_event_message_1" id="all_event_message_1">#</a></span></h3>
<div class="signature"><ul>
<li><code>message</code> <span class="type">Object</span> a parsed JSON object or primitive value</li>
<li><code>sendHandle</code> <span class="type">Handle object</span> a Socket or Server object</li>
</div></ul>
<p>Messages send by <code>.send(message, [sendHandle])</code> are obtained using the
<code>message</code> event.
</p>
<h3>child.stdin<span><a class="mark" href="#all_child_stdin" id="all_child_stdin">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Stream object</span></li>
</div></ul>
<p>A <code>Writable Stream</code> that represents the child process&#39;s <code>stdin</code>.
Closing this stream via <code>end()</code> often causes the child process to terminate.
</p>
<p>If the child stdio streams are shared with the parent, then this will
not be set.
</p>
<h3>child.stdout<span><a class="mark" href="#all_child_stdout" id="all_child_stdout">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Stream object</span></li>
</div></ul>
<p>A <code>Readable Stream</code> that represents the child process&#39;s <code>stdout</code>.
</p>
<p>If the child stdio streams are shared with the parent, then this will
not be set.
</p>
<h3>child.stderr<span><a class="mark" href="#all_child_stderr" id="all_child_stderr">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Stream object</span></li>
</div></ul>
<p>A <code>Readable Stream</code> that represents the child process&#39;s <code>stderr</code>.
</p>
<p>If the child stdio streams are shared with the parent, then this will
not be set.
</p>
<h3>child.pid<span><a class="mark" href="#all_child_pid" id="all_child_pid">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Integer</span></li>
</div></ul>
<p>The PID of the child process.
</p>
<p>Example:
</p>
<pre><code>var spawn = require(&#39;child_process&#39;).spawn,
grep = spawn(&#39;grep&#39;, [&#39;ssh&#39;]);
console.log(&#39;Spawned child pid: &#39; + grep.pid);
grep.stdin.end();</code></pre>
<h3>child.connected<span><a class="mark" href="#all_child_connected" id="all_child_connected">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Boolean</span> Set to false after `.disconnect&#39; is called</li>
</div></ul>
<p>If <code>.connected</code> is false, it is no longer possible to send messages.
</p>
<h3>child.kill([signal])<span><a class="mark" href="#all_child_kill_signal" id="all_child_kill_signal">#</a></span></h3>
<div class="signature"><ul>
<li><code>signal</code> <span class="type">String</span></li>
</div></ul>
<p>Send a signal to the child process. If no argument is given, the process will
be sent <code>&#39;SIGTERM&#39;</code>. See <code>signal(7)</code> for a list of available signals.
</p>
<pre><code>var spawn = require(&#39;child_process&#39;).spawn,
grep = spawn(&#39;grep&#39;, [&#39;ssh&#39;]);
grep.on(&#39;close&#39;, function (code, signal) {
console.log(&#39;child process terminated due to receipt of signal &#39;+signal);
});
// send SIGHUP to process
grep.kill(&#39;SIGHUP&#39;);</code></pre>
<p>May emit an <code>&#39;error&#39;</code> event when the signal cannot be delivered. Sending a
signal to a child process that has already exited is not an error but may
have unforeseen consequences: if the PID (the process ID) has been reassigned
to another process, the signal will be delivered to that process instead.
What happens next is anyone&#39;s guess.
</p>
<p>Note that while the function is called <code>kill</code>, the signal delivered to the
child process may not actually kill it. <code>kill</code> really just sends a signal
to a process.
</p>
<p>See <code>kill(2)</code>
</p>
<h3>child.send(message, [sendHandle])<span><a class="mark" href="#all_child_send_message_sendhandle" id="all_child_send_message_sendhandle">#</a></span></h3>
<div class="signature"><ul>
<li><code>message</code> <span class="type">Object</span></li>
<li><code>sendHandle</code> <span class="type">Handle object</span></li>
</div></ul>
<p>When using <code>child_process.fork()</code> you can write to the child using
<code>child.send(message, [sendHandle])</code> and messages are received by
a <code>&#39;message&#39;</code> event on the child.
</p>
<p>For example:
</p>
<pre><code>var cp = require(&#39;child_process&#39;);
var n = cp.fork(__dirname + &#39;/sub.js&#39;);
n.on(&#39;message&#39;, function(m) {
console.log(&#39;PARENT got message:&#39;, m);
});
n.send({ hello: &#39;world&#39; });</code></pre>
<p>And then the child script, <code>&#39;sub.js&#39;</code> might look like this:
</p>
<pre><code>process.on(&#39;message&#39;, function(m) {
console.log(&#39;CHILD got message:&#39;, m);
});
process.send({ foo: &#39;bar&#39; });</code></pre>
<p>In the child the <code>process</code> object will have a <code>send()</code> method, and <code>process</code>
will emit objects each time it receives a message on its channel.
</p>
<p>There is a special case when sending a <code>{cmd: &#39;NODE_foo&#39;}</code> message. All messages
containing a <code>NODE_</code> prefix in its <code>cmd</code> property will not be emitted in
the <code>message</code> event, since they are internal messages used by node core.
Messages containing the prefix are emitted in the <code>internalMessage</code> event, you
should by all means avoid using this feature, it is subject to change without notice.
</p>
<p>The <code>sendHandle</code> option to <code>child.send()</code> is for sending a TCP server or
socket object to another process. The child will receive the object as its
second argument to the <code>message</code> event.
</p>
<p>Emits an <code>&#39;error&#39;</code> event if the message cannot be sent, for example because
the child process has already exited.
</p>
<h4>Example: sending server object<span><a class="mark" href="#all_example_sending_server_object" id="all_example_sending_server_object">#</a></span></h4>
<p>Here is an example of sending a server:
</p>
<pre><code>var child = require(&#39;child_process&#39;).fork(&#39;child.js&#39;);
// Open up the server object and send the handle.
var server = require(&#39;net&#39;).createServer();
server.on(&#39;connection&#39;, function (socket) {
socket.end(&#39;handled by parent&#39;);
});
server.listen(1337, function() {
child.send(&#39;server&#39;, server);
});</code></pre>
<p>And the child would the receive the server object as:
</p>
<pre><code>process.on(&#39;message&#39;, function(m, server) {
if (m === &#39;server&#39;) {
server.on(&#39;connection&#39;, function (socket) {
socket.end(&#39;handled by child&#39;);
});
}
});</code></pre>
<p>Note that the server is now shared between the parent and child, this means
that some connections will be handled by the parent and some by the child.
</p>
<p>For <code>dgram</code> servers the workflow is exactly the same. Here you listen on
a <code>message</code> event instead of <code>connection</code> and use <code>server.bind</code> instead of
<code>server.listen</code>. (Currently only supported on UNIX platforms.)
</p>
<h4>Example: sending socket object<span><a class="mark" href="#all_example_sending_socket_object" id="all_example_sending_socket_object">#</a></span></h4>
<p>Here is an example of sending a socket. It will spawn two children and handle
connections with the remote address <code>74.125.127.100</code> as VIP by sending the
socket to a &quot;special&quot; child process. Other sockets will go to a &quot;normal&quot; process.
</p>
<pre><code>var normal = require(&#39;child_process&#39;).fork(&#39;child.js&#39;, [&#39;normal&#39;]);
var special = require(&#39;child_process&#39;).fork(&#39;child.js&#39;, [&#39;special&#39;]);
// Open up the server and send sockets to child
var server = require(&#39;net&#39;).createServer();
server.on(&#39;connection&#39;, function (socket) {
// if this is a VIP
if (socket.remoteAddress === &#39;74.125.127.100&#39;) {
special.send(&#39;socket&#39;, socket);
return;
}
// just the usual dudes
normal.send(&#39;socket&#39;, socket);
});
server.listen(1337);</code></pre>
<p>The <code>child.js</code> could look like this:
</p>
<pre><code>process.on(&#39;message&#39;, function(m, socket) {
if (m === &#39;socket&#39;) {
socket.end(&#39;You were handled as a &#39; + process.argv[2] + &#39; person&#39;);
}
});</code></pre>
<p>Note that once a single socket has been sent to a child the parent can no
longer keep track of when the socket is destroyed. To indicate this condition
the <code>.connections</code> property becomes <code>null</code>.
It is also recommended not to use <code>.maxConnections</code> in this condition.
</p>
<h3>child.disconnect()<span><a class="mark" href="#all_child_disconnect" id="all_child_disconnect">#</a></span></h3>
<p>Close the IPC channel between parent and child, allowing the child to exit
gracefully once there are no other connections keeping it alive. After calling
this method the <code>.connected</code> flag will be set to <code>false</code> in both the parent and
child, and it is no longer possible to send messages.
</p>
<p>The &#39;disconnect&#39; event will be emitted when there are no messages in the process
of being received, most likely immediately.
</p>
<p>Note that you can also call <code>process.disconnect()</code> in the child process.
</p>
<h2>child_process.spawn(command, [args], [options])<span><a class="mark" href="#all_child_process_spawn_command_args_options" id="all_child_process_spawn_command_args_options">#</a></span></h2>
<div class="signature"><ul>
<li><code>command</code> <span class="type">String</span> The command to run</li>
<li><code>args</code> <span class="type">Array</span> List of string arguments</li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>cwd</code> <span class="type">String</span> Current working directory of the child process</li>
<li><code>stdio</code> <span class="type">Array|String</span> Child&#39;s stdio configuration. (See below)</li>
<li><code>customFds</code> <span class="type">Array</span> <strong>Deprecated</strong> File descriptors for the child to use
for stdio. (See below)</li>
<li><code>env</code> <span class="type">Object</span> Environment key-value pairs</li>
<li><code>detached</code> <span class="type">Boolean</span> The child will be a process group leader. (See below)</li>
<li><code>uid</code> <span class="type">Number</span> Sets the user identity of the process. (See setuid(2).)</li>
<li><code>gid</code> <span class="type">Number</span> Sets the group identity of the process. (See setgid(2).)</li>
</ul>
</li>
<li>return: <span class="type">ChildProcess object</span></li>
</div></ul>
<p>Launches a new process with the given <code>command</code>, with command line arguments in <code>args</code>.
If omitted, <code>args</code> defaults to an empty Array.
</p>
<p>The third argument is used to specify additional options, which defaults to:
</p>
<pre><code>{ cwd: undefined,
env: process.env
}</code></pre>
<p><code>cwd</code> allows you to specify the working directory from which the process is spawned.
Use <code>env</code> to specify environment variables that will be visible to the new process.
</p>
<p>Example of running <code>ls -lh /usr</code>, capturing <code>stdout</code>, <code>stderr</code>, and the exit code:
</p>
<pre><code>var spawn = require(&#39;child_process&#39;).spawn,
ls = spawn(&#39;ls&#39;, [&#39;-lh&#39;, &#39;/usr&#39;]);
ls.stdout.on(&#39;data&#39;, function (data) {
console.log(&#39;stdout: &#39; + data);
});
ls.stderr.on(&#39;data&#39;, function (data) {
console.log(&#39;stderr: &#39; + data);
});
ls.on(&#39;close&#39;, function (code) {
console.log(&#39;child process exited with code &#39; + code);
});</code></pre>
<p>Example: A very elaborate way to run &#39;ps ax | grep ssh&#39;
</p>
<pre><code>var spawn = require(&#39;child_process&#39;).spawn,
ps = spawn(&#39;ps&#39;, [&#39;ax&#39;]),
grep = spawn(&#39;grep&#39;, [&#39;ssh&#39;]);
ps.stdout.on(&#39;data&#39;, function (data) {
grep.stdin.write(data);
});
ps.stderr.on(&#39;data&#39;, function (data) {
console.log(&#39;ps stderr: &#39; + data);
});
ps.on(&#39;close&#39;, function (code) {
if (code !== 0) {
console.log(&#39;ps process exited with code &#39; + code);
}
grep.stdin.end();
});
grep.stdout.on(&#39;data&#39;, function (data) {
console.log(&#39;&#39; + data);
});
grep.stderr.on(&#39;data&#39;, function (data) {
console.log(&#39;grep stderr: &#39; + data);
});
grep.on(&#39;close&#39;, function (code) {
if (code !== 0) {
console.log(&#39;grep process exited with code &#39; + code);
}
});</code></pre>
<p>Example of checking for failed exec:
</p>
<pre><code>var spawn = require(&#39;child_process&#39;).spawn,
child = spawn(&#39;bad_command&#39;);
child.stderr.setEncoding(&#39;utf8&#39;);
child.stderr.on(&#39;data&#39;, function (data) {
if (/^execvp\(\)/.test(data)) {
console.log(&#39;Failed to start child process.&#39;);
}
});</code></pre>
<p>Note that if spawn receives an empty options object, it will result in
spawning the process with an empty environment rather than using
<code>process.env</code>. This due to backwards compatibility issues with a deprecated
API.
</p>
<p>The &#39;stdio&#39; option to <code>child_process.spawn()</code> is an array where each
index corresponds to a fd in the child. The value is one of the following:
</p>
<ol>
<li><code>&#39;pipe&#39;</code> - Create a pipe between the child process and the parent process.
The parent end of the pipe is exposed to the parent as a property on the
<code>child_process</code> object as <code>ChildProcess.stdio[fd]</code>. Pipes created for
fds 0 - 2 are also available as ChildProcess.stdin, ChildProcess.stdout
and ChildProcess.stderr, respectively.</li>
<li><code>&#39;ipc&#39;</code> - Create an IPC channel for passing messages/file descriptors
between parent and child. A ChildProcess may have at most <em>one</em> IPC stdio
file descriptor. Setting this option enables the ChildProcess.send() method.
If the child writes JSON messages to this file descriptor, then this will
trigger ChildProcess.on(&#39;message&#39;). If the child is a Node.js program, then
the presence of an IPC channel will enable process.send() and
process.on(&#39;message&#39;).</li>
<li><code>&#39;ignore&#39;</code> - Do not set this file descriptor in the child. Note that Node
will always open fd 0 - 2 for the processes it spawns. When any of these is
ignored node will open <code>/dev/null</code> and attach it to the child&#39;s fd.</li>
<li><code>Stream</code> object - Share a readable or writable stream that refers to a tty,
file, socket, or a pipe with the child process. The stream&#39;s underlying
file descriptor is duplicated in the child process to the fd that
corresponds to the index in the <code>stdio</code> array.</li>
<li>Positive integer - The integer value is interpreted as a file descriptor
that is is currently open in the parent process. It is shared with the child
process, similar to how <code>Stream</code> objects can be shared.</li>
<li><code>null</code>, <code>undefined</code> - Use default value. For stdio fds 0, 1 and 2 (in other
words, stdin, stdout, and stderr) a pipe is created. For fd 3 and up, the
default is <code>&#39;ignore&#39;</code>.</li>
</ol>
<p>As a shorthand, the <code>stdio</code> argument may also be one of the following
strings, rather than an array:
</p>
<ul>
<li><code>ignore</code> - <code>[&#39;ignore&#39;, &#39;ignore&#39;, &#39;ignore&#39;]</code></li>
<li><code>pipe</code> - <code>[&#39;pipe&#39;, &#39;pipe&#39;, &#39;pipe&#39;]</code></li>
<li><code>inherit</code> - <code>[process.stdin, process.stdout, process.stderr]</code> or <code>[0,1,2]</code></li>
</ul>
<p>Example:
</p>
<pre><code>var spawn = require(&#39;child_process&#39;).spawn;
// Child will use parent&#39;s stdios
spawn(&#39;prg&#39;, [], { stdio: &#39;inherit&#39; });
// Spawn child sharing only stderr
spawn(&#39;prg&#39;, [], { stdio: [&#39;pipe&#39;, &#39;pipe&#39;, process.stderr] });
// Open an extra fd=4, to interact with programs present a
// startd-style interface.
spawn(&#39;prg&#39;, [], { stdio: [&#39;pipe&#39;, null, null, null, &#39;pipe&#39;] });</code></pre>
<p>If the <code>detached</code> option is set, the child process will be made the leader of a
new process group. This makes it possible for the child to continue running
after the parent exits.
</p>
<p>By default, the parent will wait for the detached child to exit. To prevent
the parent from waiting for a given <code>child</code>, use the <code>child.unref()</code> method,
and the parent&#39;s event loop will not include the child in its reference count.
</p>
<p>Example of detaching a long-running process and redirecting its output to a
file:
</p>
<pre><code> var fs = require(&#39;fs&#39;),
spawn = require(&#39;child_process&#39;).spawn,
out = fs.openSync(&#39;./out.log&#39;, &#39;a&#39;),
err = fs.openSync(&#39;./out.log&#39;, &#39;a&#39;);
var child = spawn(&#39;prg&#39;, [], {
detached: true,
stdio: [ &#39;ignore&#39;, out, err ]
});
child.unref();</code></pre>
<p>When using the <code>detached</code> option to start a long-running process, the process
will not stay running in the background unless it is provided with a <code>stdio</code>
configuration that is not connected to the parent. If the parent&#39;s <code>stdio</code> is
inherited, the child will remain attached to the controlling terminal.
</p>
<p>There is a deprecated option called <code>customFds</code> which allows one to specify
specific file descriptors for the stdio of the child process. This API was
not portable to all platforms and therefore removed.
With <code>customFds</code> it was possible to hook up the new process&#39; <code>[stdin, stdout,
stderr]</code> to existing streams; <code>-1</code> meant that a new stream should be created.
Use at your own risk.
</p>
<p>See also: <code>child_process.exec()</code> and <code>child_process.fork()</code>
</p>
<h2>child_process.exec(command, [options], callback)<span><a class="mark" href="#all_child_process_exec_command_options_callback" id="all_child_process_exec_command_options_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>command</code> <span class="type">String</span> The command to run, with space-separated arguments</li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>cwd</code> <span class="type">String</span> Current working directory of the child process</li>
<li><code>env</code> <span class="type">Object</span> Environment key-value pairs</li>
<li><code>encoding</code> <span class="type">String</span> (Default: &#39;utf8&#39;)</li>
<li><code>timeout</code> <span class="type">Number</span> (Default: 0)</li>
<li><code>maxBuffer</code> <span class="type">Number</span> (Default: <code>200*1024</code>)</li>
<li><code>killSignal</code> <span class="type">String</span> (Default: &#39;SIGTERM&#39;)</li>
</ul>
</li>
<li><code>callback</code> <span class="type">Function</span> called with the output when process terminates<ul>
<li><code>error</code> <span class="type">Error</span></li>
<li><code>stdout</code> <span class="type">Buffer</span></li>
<li><code>stderr</code> <span class="type">Buffer</span></li>
</ul>
</li>
<li>Return: ChildProcess object</li>
</div></ul>
<p>Runs a command in a shell and buffers the output.
</p>
<pre><code>var exec = require(&#39;child_process&#39;).exec,
child;
child = exec(&#39;cat *.js bad_file | wc -l&#39;,
function (error, stdout, stderr) {
console.log(&#39;stdout: &#39; + stdout);
console.log(&#39;stderr: &#39; + stderr);
if (error !== null) {
console.log(&#39;exec error: &#39; + error);
}
});</code></pre>
<p>The callback gets the arguments <code>(error, stdout, stderr)</code>. On success, <code>error</code>
will be <code>null</code>. On error, <code>error</code> will be an instance of <code>Error</code> and <code>err.code</code>
will be the exit code of the child process, and <code>err.signal</code> will be set to the
signal that terminated the process.
</p>
<p>There is a second optional argument to specify several options. The
default options are
</p>
<pre><code>{ encoding: &#39;utf8&#39;,
timeout: 0,
maxBuffer: 200*1024,
killSignal: &#39;SIGTERM&#39;,
cwd: null,
env: null }</code></pre>
<p>If <code>timeout</code> is greater than 0, then it will kill the child process
if it runs longer than <code>timeout</code> milliseconds. The child process is killed with
<code>killSignal</code> (default: <code>&#39;SIGTERM&#39;</code>). <code>maxBuffer</code> specifies the largest
amount of data allowed on stdout or stderr - if this value is exceeded then
the child process is killed.
</p>
<h2>child_process.execFile(file, args, options, callback)<span><a class="mark" href="#all_child_process_execfile_file_args_options_callback" id="all_child_process_execfile_file_args_options_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>file</code> <span class="type">String</span> The filename of the program to run</li>
<li><code>args</code> <span class="type">Array</span> List of string arguments</li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>cwd</code> <span class="type">String</span> Current working directory of the child process</li>
<li><code>env</code> <span class="type">Object</span> Environment key-value pairs</li>
<li><code>encoding</code> <span class="type">String</span> (Default: &#39;utf8&#39;)</li>
<li><code>timeout</code> <span class="type">Number</span> (Default: 0)</li>
<li><code>maxBuffer</code> <span class="type">Number</span> (Default: 200*1024)</li>
<li><code>killSignal</code> <span class="type">String</span> (Default: &#39;SIGTERM&#39;)</li>
</ul>
</li>
<li><code>callback</code> <span class="type">Function</span> called with the output when process terminates<ul>
<li><code>error</code> <span class="type">Error</span></li>
<li><code>stdout</code> <span class="type">Buffer</span></li>
<li><code>stderr</code> <span class="type">Buffer</span></li>
</ul>
</li>
<li>Return: ChildProcess object</li>
</div></ul>
<p>This is similar to <code>child_process.exec()</code> except it does not execute a
subshell but rather the specified file directly. This makes it slightly
leaner than <code>child_process.exec</code>. It has the same options.
</p>
<h2>child_process.fork(modulePath, [args], [options])<span><a class="mark" href="#all_child_process_fork_modulepath_args_options" id="all_child_process_fork_modulepath_args_options">#</a></span></h2>
<div class="signature"><ul>
<li><code>modulePath</code> <span class="type">String</span> The module to run in the child</li>
<li><code>args</code> <span class="type">Array</span> List of string arguments</li>
<li><code>options</code> <span class="type">Object</span><ul>
<li><code>cwd</code> <span class="type">String</span> Current working directory of the child process</li>
<li><code>env</code> <span class="type">Object</span> Environment key-value pairs</li>
<li><code>encoding</code> <span class="type">String</span> (Default: &#39;utf8&#39;)</li>
<li><code>execPath</code> <span class="type">String</span> Executable used to create the child process</li>
<li><code>execArgv</code> <span class="type">Array</span> List of string arguments passed to the executable
(Default: <code>process.execArgv</code>)</li>
<li><code>silent</code> <span class="type">Boolean</span> If true, prevent stdout and stderr in the spawned node
process from being associated with the parent&#39;s (default is false)</li>
</ul>
</li>
<li>Return: ChildProcess object</li>
</div></ul>
<p>This is a special case of the <code>spawn()</code> functionality for spawning Node
processes. In addition to having all the methods in a normal ChildProcess
instance, the returned object has a communication channel built-in. See
<code>child.send(message, [sendHandle])</code> for details.
</p>
<p>These child Nodes are still whole new instances of V8. Assume at least 30ms
startup and 10mb memory for each new Node. That is, you cannot create many
thousands of them.
</p>
<p>The <code>execPath</code> property in the <code>options</code> object allows for a process to be
created for the child rather than the current <code>node</code> executable. This should be
done with care and by default will talk over the fd represented an
environmental variable <code>NODE_CHANNEL_FD</code> on the child process. The input and
output on this fd is expected to be line delimited JSON objects.
</p>
<h1>Assert<span><a class="mark" href="#all_assert" id="all_assert">#</a></span></h1>
<pre class="api_stability_5">Stability: 5 - Locked</pre><p>This module is used for writing unit tests for your applications, you can
access it with <code>require(&#39;assert&#39;)</code>.
</p>
<h2>assert.fail(actual, expected, message, operator)<span><a class="mark" href="#all_assert_fail_actual_expected_message_operator" id="all_assert_fail_actual_expected_message_operator">#</a></span></h2>
<p>Throws an exception that displays the values for <code>actual</code> and <code>expected</code> separated by the provided operator.
</p>
<h2>assert(value, message), assert.ok(value, [message])<span><a class="mark" href="#all_assert_value_message_assert_ok_value_message" id="all_assert_value_message_assert_ok_value_message">#</a></span></h2>
<p>Tests if value is truthy, it is equivalent to <code>assert.equal(true, !!value, message);</code>
</p>
<h2>assert.equal(actual, expected, [message])<span><a class="mark" href="#all_assert_equal_actual_expected_message" id="all_assert_equal_actual_expected_message">#</a></span></h2>
<p>Tests shallow, coercive equality with the equal comparison operator ( <code>==</code> ).
</p>
<h2>assert.notEqual(actual, expected, [message])<span><a class="mark" href="#all_assert_notequal_actual_expected_message" id="all_assert_notequal_actual_expected_message">#</a></span></h2>
<p>Tests shallow, coercive non-equality with the not equal comparison operator ( <code>!=</code> ).
</p>
<h2>assert.deepEqual(actual, expected, [message])<span><a class="mark" href="#all_assert_deepequal_actual_expected_message" id="all_assert_deepequal_actual_expected_message">#</a></span></h2>
<p>Tests for deep equality.
</p>
<h2>assert.notDeepEqual(actual, expected, [message])<span><a class="mark" href="#all_assert_notdeepequal_actual_expected_message" id="all_assert_notdeepequal_actual_expected_message">#</a></span></h2>
<p>Tests for any deep inequality.
</p>
<h2>assert.strictEqual(actual, expected, [message])<span><a class="mark" href="#all_assert_strictequal_actual_expected_message" id="all_assert_strictequal_actual_expected_message">#</a></span></h2>
<p>Tests strict equality, as determined by the strict equality operator ( <code>===</code> )
</p>
<h2>assert.notStrictEqual(actual, expected, [message])<span><a class="mark" href="#all_assert_notstrictequal_actual_expected_message" id="all_assert_notstrictequal_actual_expected_message">#</a></span></h2>
<p>Tests strict non-equality, as determined by the strict not equal operator ( <code>!==</code> )
</p>
<h2>assert.throws(block, [error], [message])<span><a class="mark" href="#all_assert_throws_block_error_message" id="all_assert_throws_block_error_message">#</a></span></h2>
<p>Expects <code>block</code> to throw an error. <code>error</code> can be constructor, regexp or
validation function.
</p>
<p>Validate instanceof using constructor:
</p>
<pre><code>assert.throws(
function() {
throw new Error(&quot;Wrong value&quot;);
},
Error
);</code></pre>
<p>Validate error message using RegExp:
</p>
<pre><code>assert.throws(
function() {
throw new Error(&quot;Wrong value&quot;);
},
/value/
);</code></pre>
<p>Custom error validation:
</p>
<pre><code>assert.throws(
function() {
throw new Error(&quot;Wrong value&quot;);
},
function(err) {
if ( (err instanceof Error) &amp;&amp; /value/.test(err) ) {
return true;
}
},
&quot;unexpected error&quot;
);</code></pre>
<h2>assert.doesNotThrow(block, [message])<span><a class="mark" href="#all_assert_doesnotthrow_block_message" id="all_assert_doesnotthrow_block_message">#</a></span></h2>
<p>Expects <code>block</code> not to throw an error, see assert.throws for details.
</p>
<h2>assert.ifError(value)<span><a class="mark" href="#all_assert_iferror_value" id="all_assert_iferror_value">#</a></span></h2>
<p>Tests if value is not a false value, throws if it is a true value. Useful when
testing the first argument, <code>error</code> in callbacks.
</p>
<h1>TTY<span><a class="mark" href="#all_tty" id="all_tty">#</a></span></h1>
<pre class="api_stability_2">Stability: 2 - Unstable</pre><p>The <code>tty</code> module houses the <code>tty.ReadStream</code> and <code>tty.WriteStream</code> classes. In
most cases, you will not need to use this module directly.
</p>
<p>When node detects that it is being run inside a TTY context, then <code>process.stdin</code>
will be a <code>tty.ReadStream</code> instance and <code>process.stdout</code> will be
a <code>tty.WriteStream</code> instance. The preferred way to check if node is being run in
a TTY context is to check <code>process.stdout.isTTY</code>:
</p>
<pre><code>$ node -p -e &quot;Boolean(process.stdout.isTTY)&quot;
true
$ node -p -e &quot;Boolean(process.stdout.isTTY)&quot; | cat
false</code></pre>
<h2>tty.isatty(fd)<span><a class="mark" href="#all_tty_isatty_fd" id="all_tty_isatty_fd">#</a></span></h2>
<p>Returns <code>true</code> or <code>false</code> depending on if the <code>fd</code> is associated with a
terminal.
</p>
<h2>tty.setRawMode(mode)<span><a class="mark" href="#all_tty_setrawmode_mode" id="all_tty_setrawmode_mode">#</a></span></h2>
<p>Deprecated. Use <code>tty.ReadStream#setRawMode()</code>
(i.e. <code>process.stdin.setRawMode()</code>) instead.
</p>
<h2>Class: ReadStream<span><a class="mark" href="#all_class_readstream" id="all_class_readstream">#</a></span></h2>
<p>A <code>net.Socket</code> subclass that represents the readable portion of a tty. In normal
circumstances, <code>process.stdin</code> will be the only <code>tty.ReadStream</code> instance in any
node program (only when <code>isatty(0)</code> is true).
</p>
<h3>rs.isRaw<span><a class="mark" href="#all_rs_israw" id="all_rs_israw">#</a></span></h3>
<p>A <code>Boolean</code> that is initialized to <code>false</code>. It represents the current &quot;raw&quot; state
of the <code>tty.ReadStream</code> instance.
</p>
<h3>rs.setRawMode(mode)<span><a class="mark" href="#all_rs_setrawmode_mode" id="all_rs_setrawmode_mode">#</a></span></h3>
<p><code>mode</code> should be <code>true</code> or <code>false</code>. This sets the properties of the
<code>tty.ReadStream</code> to act either as a raw device or default. <code>isRaw</code> will be set
to the resulting mode.
</p>
<h2>Class: WriteStream<span><a class="mark" href="#all_class_writestream" id="all_class_writestream">#</a></span></h2>
<p>A <code>net.Socket</code> subclass that represents the writable portion of a tty. In normal
circumstances, <code>process.stdout</code> will be the only <code>tty.WriteStream</code> instance
ever created (and only when <code>isatty(1)</code> is true).
</p>
<h3>ws.columns<span><a class="mark" href="#all_ws_columns" id="all_ws_columns">#</a></span></h3>
<p>A <code>Number</code> that gives the number of columns the TTY currently has. This property
gets updated on &quot;resize&quot; events.
</p>
<h3>ws.rows<span><a class="mark" href="#all_ws_rows" id="all_ws_rows">#</a></span></h3>
<p>A <code>Number</code> that gives the number of rows the TTY currently has. This property
gets updated on &quot;resize&quot; events.
</p>
<h3>Event: &#39;resize&#39;<span><a class="mark" href="#all_event_resize" id="all_event_resize">#</a></span></h3>
<p><code>function () {}</code>
</p>
<p>Emitted by <code>refreshSize()</code> when either of the <code>columns</code> or <code>rows</code> properties
has changed.
</p>
<pre><code>process.stdout.on(&#39;resize&#39;, function() {
console.log(&#39;screen size has changed!&#39;);
console.log(process.stdout.columns + &#39;x&#39; + process.stdout.rows);
});</code></pre>
<h1>Zlib<span><a class="mark" href="#all_zlib" id="all_zlib">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><p>You can access this module with:
</p>
<pre><code>var zlib = require(&#39;zlib&#39;);</code></pre>
<p>This provides bindings to Gzip/Gunzip, Deflate/Inflate, and
DeflateRaw/InflateRaw classes. Each class takes the same options, and
is a readable/writable Stream.
</p>
<h2>Examples<span><a class="mark" href="#all_examples" id="all_examples">#</a></span></h2>
<p>Compressing or decompressing a file can be done by piping an
fs.ReadStream into a zlib stream, then into an fs.WriteStream.
</p>
<pre><code>var gzip = zlib.createGzip();
var fs = require(&#39;fs&#39;);
var inp = fs.createReadStream(&#39;input.txt&#39;);
var out = fs.createWriteStream(&#39;input.txt.gz&#39;);
inp.pipe(gzip).pipe(out);</code></pre>
<p>Compressing or decompressing data in one step can be done by using
the convenience methods.
</p>
<pre><code>var input = &#39;.................................&#39;;
zlib.deflate(input, function(err, buffer) {
if (!err) {
console.log(buffer.toString(&#39;base64&#39;));
}
});
var buffer = new Buffer(&#39;eJzT0yMAAGTvBe8=&#39;, &#39;base64&#39;);
zlib.unzip(buffer, function(err, buffer) {
if (!err) {
console.log(buffer.toString());
}
});</code></pre>
<p>To use this module in an HTTP client or server, use the
<a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.3">accept-encoding</a>
on requests, and the
<a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.11">content-encoding</a>
header on responses.
</p>
<p><strong>Note: these examples are drastically simplified to show
the basic concept.</strong> Zlib encoding can be expensive, and the results
ought to be cached. See <a href="#zlib_memory_usage_tuning">Memory Usage Tuning</a>
below for more information on the speed/memory/compression
tradeoffs involved in zlib usage.
</p>
<pre><code>// client request example
var zlib = require(&#39;zlib&#39;);
var http = require(&#39;http&#39;);
var fs = require(&#39;fs&#39;);
var request = http.get({ host: &#39;izs.me&#39;,
path: &#39;/&#39;,
port: 80,
headers: { &#39;accept-encoding&#39;: &#39;gzip,deflate&#39; } });
request.on(&#39;response&#39;, function(response) {
var output = fs.createWriteStream(&#39;izs.me_index.html&#39;);
switch (response.headers[&#39;content-encoding&#39;]) {
// or, just use zlib.createUnzip() to handle both cases
case &#39;gzip&#39;:
response.pipe(zlib.createGunzip()).pipe(output);
break;
case &#39;deflate&#39;:
response.pipe(zlib.createInflate()).pipe(output);
break;
default:
response.pipe(output);
break;
}
});
// server example
// Running a gzip operation on every request is quite expensive.
// It would be much more efficient to cache the compressed buffer.
var zlib = require(&#39;zlib&#39;);
var http = require(&#39;http&#39;);
var fs = require(&#39;fs&#39;);
http.createServer(function(request, response) {
var raw = fs.createReadStream(&#39;index.html&#39;);
var acceptEncoding = request.headers[&#39;accept-encoding&#39;];
if (!acceptEncoding) {
acceptEncoding = &#39;&#39;;
}
// Note: this is not a conformant accept-encoding parser.
// See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.3
if (acceptEncoding.match(/\bdeflate\b/)) {
response.writeHead(200, { &#39;content-encoding&#39;: &#39;deflate&#39; });
raw.pipe(zlib.createDeflate()).pipe(response);
} else if (acceptEncoding.match(/\bgzip\b/)) {
response.writeHead(200, { &#39;content-encoding&#39;: &#39;gzip&#39; });
raw.pipe(zlib.createGzip()).pipe(response);
} else {
response.writeHead(200, {});
raw.pipe(response);
}
}).listen(1337);</code></pre>
<h2>zlib.createGzip([options])<span><a class="mark" href="#all_zlib_creategzip_options" id="all_zlib_creategzip_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_gzip">Gzip</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>zlib.createGunzip([options])<span><a class="mark" href="#all_zlib_creategunzip_options" id="all_zlib_creategunzip_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_gunzip">Gunzip</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>zlib.createDeflate([options])<span><a class="mark" href="#all_zlib_createdeflate_options" id="all_zlib_createdeflate_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_deflate">Deflate</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>zlib.createInflate([options])<span><a class="mark" href="#all_zlib_createinflate_options" id="all_zlib_createinflate_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_inflate">Inflate</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>zlib.createDeflateRaw([options])<span><a class="mark" href="#all_zlib_createdeflateraw_options" id="all_zlib_createdeflateraw_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_deflateraw">DeflateRaw</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>zlib.createInflateRaw([options])<span><a class="mark" href="#all_zlib_createinflateraw_options" id="all_zlib_createinflateraw_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_inflateraw">InflateRaw</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>zlib.createUnzip([options])<span><a class="mark" href="#all_zlib_createunzip_options" id="all_zlib_createunzip_options">#</a></span></h2>
<p>Returns a new <a href="#zlib_class_zlib_unzip">Unzip</a> object with an
<a href="#zlib_options">options</a>.
</p>
<h2>Class: zlib.Zlib<span><a class="mark" href="#all_class_zlib_zlib" id="all_class_zlib_zlib">#</a></span></h2>
<p>Not exported by the <code>zlib</code> module. It is documented here because it is the base
class of the compressor/decompressor classes.
</p>
<h3>zlib.flush(callback)<span><a class="mark" href="#all_zlib_flush_callback" id="all_zlib_flush_callback">#</a></span></h3>
<p>Flush pending data. Don&#39;t call this frivolously, premature flushes negatively
impact the effectiveness of the compression algorithm.
</p>
<h3>zlib.reset()<span><a class="mark" href="#all_zlib_reset" id="all_zlib_reset">#</a></span></h3>
<p>Reset the compressor/decompressor to factory defaults. Only applicable to
the inflate and deflate algorithms.
</p>
<h2>Class: zlib.Gzip<span><a class="mark" href="#all_class_zlib_gzip" id="all_class_zlib_gzip">#</a></span></h2>
<p>Compress data using gzip.
</p>
<h2>Class: zlib.Gunzip<span><a class="mark" href="#all_class_zlib_gunzip" id="all_class_zlib_gunzip">#</a></span></h2>
<p>Decompress a gzip stream.
</p>
<h2>Class: zlib.Deflate<span><a class="mark" href="#all_class_zlib_deflate" id="all_class_zlib_deflate">#</a></span></h2>
<p>Compress data using deflate.
</p>
<h2>Class: zlib.Inflate<span><a class="mark" href="#all_class_zlib_inflate" id="all_class_zlib_inflate">#</a></span></h2>
<p>Decompress a deflate stream.
</p>
<h2>Class: zlib.DeflateRaw<span><a class="mark" href="#all_class_zlib_deflateraw" id="all_class_zlib_deflateraw">#</a></span></h2>
<p>Compress data using deflate, and do not append a zlib header.
</p>
<h2>Class: zlib.InflateRaw<span><a class="mark" href="#all_class_zlib_inflateraw" id="all_class_zlib_inflateraw">#</a></span></h2>
<p>Decompress a raw deflate stream.
</p>
<h2>Class: zlib.Unzip<span><a class="mark" href="#all_class_zlib_unzip" id="all_class_zlib_unzip">#</a></span></h2>
<p>Decompress either a Gzip- or Deflate-compressed stream by auto-detecting
the header.
</p>
<h2>Convenience Methods<span><a class="mark" href="#all_convenience_methods" id="all_convenience_methods">#</a></span></h2>
<!--type=misc-->
<p>All of these take a string or buffer as the first argument, and call the
supplied callback with <code>callback(error, result)</code>. The
compression/decompression engine is created using the default settings
in all convenience methods. To supply different options, use the
zlib classes directly.
</p>
<h2>zlib.deflate(buf, callback)<span><a class="mark" href="#all_zlib_deflate_buf_callback" id="all_zlib_deflate_buf_callback">#</a></span></h2>
<p>Compress a string with Deflate.
</p>
<h2>zlib.deflateRaw(buf, callback)<span><a class="mark" href="#all_zlib_deflateraw_buf_callback" id="all_zlib_deflateraw_buf_callback">#</a></span></h2>
<p>Compress a string with DeflateRaw.
</p>
<h2>zlib.gzip(buf, callback)<span><a class="mark" href="#all_zlib_gzip_buf_callback" id="all_zlib_gzip_buf_callback">#</a></span></h2>
<p>Compress a string with Gzip.
</p>
<h2>zlib.gunzip(buf, callback)<span><a class="mark" href="#all_zlib_gunzip_buf_callback" id="all_zlib_gunzip_buf_callback">#</a></span></h2>
<p>Decompress a raw Buffer with Gunzip.
</p>
<h2>zlib.inflate(buf, callback)<span><a class="mark" href="#all_zlib_inflate_buf_callback" id="all_zlib_inflate_buf_callback">#</a></span></h2>
<p>Decompress a raw Buffer with Inflate.
</p>
<h2>zlib.inflateRaw(buf, callback)<span><a class="mark" href="#all_zlib_inflateraw_buf_callback" id="all_zlib_inflateraw_buf_callback">#</a></span></h2>
<p>Decompress a raw Buffer with InflateRaw.
</p>
<h2>zlib.unzip(buf, callback)<span><a class="mark" href="#all_zlib_unzip_buf_callback" id="all_zlib_unzip_buf_callback">#</a></span></h2>
<p>Decompress a raw Buffer with Unzip.
</p>
<h2>Options<span><a class="mark" href="#all_options" id="all_options">#</a></span></h2>
<!--type=misc-->
<p>Each class takes an options object. All options are optional. (The
convenience methods use the default settings for all options.)
</p>
<p>Note that some options are only relevant when compressing, and are
ignored by the decompression classes.
</p>
<ul>
<li>flush (default: <code>zlib.Z_NO_FLUSH</code>)</li>
<li>chunkSize (default: 16*1024)</li>
<li>windowBits</li>
<li>level (compression only)</li>
<li>memLevel (compression only)</li>
<li>strategy (compression only)</li>
<li>dictionary (deflate/inflate only, empty dictionary by default)</li>
</ul>
<p>See the description of <code>deflateInit2</code> and <code>inflateInit2</code> at
</p>
<p><a href="http://zlib.net/manual.html#Advanced">http://zlib.net/manual.html#Advanced</a> for more information on these.
</p>
<h2>Memory Usage Tuning<span><a class="mark" href="#all_memory_usage_tuning" id="all_memory_usage_tuning">#</a></span></h2>
<!--type=misc-->
<p>From <code>zlib/zconf.h</code>, modified to node&#39;s usage:
</p>
<p>The memory requirements for deflate are (in bytes):
</p>
<pre><code>(1 &lt;&lt; (windowBits+2)) + (1 &lt;&lt; (memLevel+9))</code></pre>
<p>that is: 128K for windowBits=15 + 128K for memLevel = 8
(default values) plus a few kilobytes for small objects.
</p>
<p>For example, if you want to reduce
the default memory requirements from 256K to 128K, set the options to:
</p>
<pre><code>{ windowBits: 14, memLevel: 7 }</code></pre>
<p>Of course this will generally degrade compression (there&#39;s no free lunch).
</p>
<p>The memory requirements for inflate are (in bytes)
</p>
<pre><code>1 &lt;&lt; windowBits</code></pre>
<p>that is, 32K for windowBits=15 (default value) plus a few kilobytes
for small objects.
</p>
<p>This is in addition to a single internal output slab buffer of size
<code>chunkSize</code>, which defaults to 16K.
</p>
<p>The speed of zlib compression is affected most dramatically by the
<code>level</code> setting. A higher level will result in better compression, but
will take longer to complete. A lower level will result in less
compression, but will be much faster.
</p>
<p>In general, greater memory usage options will mean that node has to make
fewer calls to zlib, since it&#39;ll be able to process more data in a
single <code>write</code> operation. So, this is another factor that affects the
speed, at the cost of memory usage.
</p>
<h2>Constants<span><a class="mark" href="#all_constants" id="all_constants">#</a></span></h2>
<!--type=misc-->
<p>All of the constants defined in zlib.h are also defined on
<code>require(&#39;zlib&#39;)</code>.
In the normal course of operations, you will not need to ever set any of
these. They are documented here so that their presence is not
surprising. This section is taken almost directly from the <a href="http://zlib.net/manual.html#Constants">zlib
documentation</a>. See
</p>
<p><a href="http://zlib.net/manual.html#Constants">http://zlib.net/manual.html#Constants</a> for more details.
</p>
<p>Allowed flush values.
</p>
<ul>
<li><code>zlib.Z_NO_FLUSH</code></li>
<li><code>zlib.Z_PARTIAL_FLUSH</code></li>
<li><code>zlib.Z_SYNC_FLUSH</code></li>
<li><code>zlib.Z_FULL_FLUSH</code></li>
<li><code>zlib.Z_FINISH</code></li>
<li><code>zlib.Z_BLOCK</code></li>
<li><code>zlib.Z_TREES</code></li>
</ul>
<p>Return codes for the compression/decompression functions. Negative
values are errors, positive values are used for special but normal
events.
</p>
<ul>
<li><code>zlib.Z_OK</code></li>
<li><code>zlib.Z_STREAM_END</code></li>
<li><code>zlib.Z_NEED_DICT</code></li>
<li><code>zlib.Z_ERRNO</code></li>
<li><code>zlib.Z_STREAM_ERROR</code></li>
<li><code>zlib.Z_DATA_ERROR</code></li>
<li><code>zlib.Z_MEM_ERROR</code></li>
<li><code>zlib.Z_BUF_ERROR</code></li>
<li><code>zlib.Z_VERSION_ERROR</code></li>
</ul>
<p>Compression levels.
</p>
<ul>
<li><code>zlib.Z_NO_COMPRESSION</code></li>
<li><code>zlib.Z_BEST_SPEED</code></li>
<li><code>zlib.Z_BEST_COMPRESSION</code></li>
<li><code>zlib.Z_DEFAULT_COMPRESSION</code></li>
</ul>
<p>Compression strategy.
</p>
<ul>
<li><code>zlib.Z_FILTERED</code></li>
<li><code>zlib.Z_HUFFMAN_ONLY</code></li>
<li><code>zlib.Z_RLE</code></li>
<li><code>zlib.Z_FIXED</code></li>
<li><code>zlib.Z_DEFAULT_STRATEGY</code></li>
</ul>
<p>Possible values of the data_type field.
</p>
<ul>
<li><code>zlib.Z_BINARY</code></li>
<li><code>zlib.Z_TEXT</code></li>
<li><code>zlib.Z_ASCII</code></li>
<li><code>zlib.Z_UNKNOWN</code></li>
</ul>
<p>The deflate compression method (the only one supported in this version).
</p>
<ul>
<li><code>zlib.Z_DEFLATED</code></li>
</ul>
<p>For initializing zalloc, zfree, opaque.
</p>
<ul>
<li><code>zlib.Z_NULL</code></li>
</ul>
<h1>os<span><a class="mark" href="#all_os" id="all_os">#</a></span></h1>
<pre class="api_stability_4">Stability: 4 - API Frozen</pre><p>Provides a few basic operating-system related utility functions.
</p>
<p>Use <code>require(&#39;os&#39;)</code> to access this module.
</p>
<h2>os.tmpdir()<span><a class="mark" href="#all_os_tmpdir" id="all_os_tmpdir">#</a></span></h2>
<p>Returns the operating system&#39;s default directory for temp files.
</p>
<h2>os.endianness()<span><a class="mark" href="#all_os_endianness" id="all_os_endianness">#</a></span></h2>
<p>Returns the endianness of the CPU. Possible values are <code>&quot;BE&quot;</code> or <code>&quot;LE&quot;</code>.
</p>
<h2>os.hostname()<span><a class="mark" href="#all_os_hostname" id="all_os_hostname">#</a></span></h2>
<p>Returns the hostname of the operating system.
</p>
<h2>os.type()<span><a class="mark" href="#all_os_type" id="all_os_type">#</a></span></h2>
<p>Returns the operating system name.
</p>
<h2>os.platform()<span><a class="mark" href="#all_os_platform" id="all_os_platform">#</a></span></h2>
<p>Returns the operating system platform.
</p>
<h2>os.arch()<span><a class="mark" href="#all_os_arch" id="all_os_arch">#</a></span></h2>
<p>Returns the operating system CPU architecture.
</p>
<h2>os.release()<span><a class="mark" href="#all_os_release" id="all_os_release">#</a></span></h2>
<p>Returns the operating system release.
</p>
<h2>os.uptime()<span><a class="mark" href="#all_os_uptime" id="all_os_uptime">#</a></span></h2>
<p>Returns the system uptime in seconds.
</p>
<h2>os.loadavg()<span><a class="mark" href="#all_os_loadavg" id="all_os_loadavg">#</a></span></h2>
<p>Returns an array containing the 1, 5, and 15 minute load averages.
</p>
<p>The load average is a measure of system activity, calculated by the operating
system and expressed as a fractional number. As a rule of thumb, the load
average should ideally be less than the number of logical CPUs in the system.
</p>
<p>The load average is a very UNIX-y concept; there is no real equivalent on
Windows platforms. That is why this function always returns <code>[0, 0, 0]</code> on
Windows.
</p>
<h2>os.totalmem()<span><a class="mark" href="#all_os_totalmem" id="all_os_totalmem">#</a></span></h2>
<p>Returns the total amount of system memory in bytes.
</p>
<h2>os.freemem()<span><a class="mark" href="#all_os_freemem" id="all_os_freemem">#</a></span></h2>
<p>Returns the amount of free system memory in bytes.
</p>
<h2>os.cpus()<span><a class="mark" href="#all_os_cpus" id="all_os_cpus">#</a></span></h2>
<p>Returns an array of objects containing information about each CPU/core
installed: model, speed (in MHz), and times (an object containing the number of
milliseconds the CPU/core spent in: user, nice, sys, idle, and irq).
</p>
<p>Example inspection of os.cpus:
</p>
<pre><code>[ { model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 252020,
nice: 0,
sys: 30340,
idle: 1070356870,
irq: 0 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 306960,
nice: 0,
sys: 26980,
idle: 1071569080,
irq: 0 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 248450,
nice: 0,
sys: 21750,
idle: 1070919370,
irq: 0 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 256880,
nice: 0,
sys: 19430,
idle: 1070905480,
irq: 20 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 511580,
nice: 20,
sys: 40900,
idle: 1070842510,
irq: 0 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 291660,
nice: 0,
sys: 34360,
idle: 1070888000,
irq: 10 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 308260,
nice: 0,
sys: 55410,
idle: 1071129970,
irq: 880 } },
{ model: &#39;Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz&#39;,
speed: 2926,
times:
{ user: 266450,
nice: 1480,
sys: 34920,
idle: 1072572010,
irq: 30 } } ]</code></pre>
<h2>os.networkInterfaces()<span><a class="mark" href="#all_os_networkinterfaces" id="all_os_networkinterfaces">#</a></span></h2>
<p>Get a list of network interfaces:
</p>
<pre><code>{ lo0:
[ { address: &#39;::1&#39;, family: &#39;IPv6&#39;, internal: true },
{ address: &#39;fe80::1&#39;, family: &#39;IPv6&#39;, internal: true },
{ address: &#39;127.0.0.1&#39;, family: &#39;IPv4&#39;, internal: true } ],
en1:
[ { address: &#39;fe80::cabc:c8ff:feef:f996&#39;, family: &#39;IPv6&#39;,
internal: false },
{ address: &#39;10.0.1.123&#39;, family: &#39;IPv4&#39;, internal: false } ],
vmnet1: [ { address: &#39;10.99.99.254&#39;, family: &#39;IPv4&#39;, internal: false } ],
vmnet8: [ { address: &#39;10.88.88.1&#39;, family: &#39;IPv4&#39;, internal: false } ],
ppp0: [ { address: &#39;10.2.0.231&#39;, family: &#39;IPv4&#39;, internal: false } ] }</code></pre>
<h2>os.EOL<span><a class="mark" href="#all_os_eol" id="all_os_eol">#</a></span></h2>
<p>A constant defining the appropriate End-of-line marker for the operating system.
</p>
<h1>Debugger<span><a class="mark" href="#all_debugger" id="all_debugger">#</a></span></h1>
<pre class="api_stability_3">Stability: 3 - Stable</pre><!-- type=misc -->
<p>V8 comes with an extensive debugger which is accessible out-of-process via a
simple <a href="http://code.google.com/p/v8/wiki/DebuggerProtocol">TCP protocol</a>.
Node has a built-in client for this debugger. To use this, start Node with the
<code>debug</code> argument; a prompt will appear:
</p>
<pre><code>% node debug myscript.js
&lt; debugger listening on port 5858
connecting... ok
break in /home/indutny/Code/git/indutny/myscript.js:1
1 x = 5;
2 setTimeout(function () {
3 debugger;
debug&gt;</code></pre>
<p>Node&#39;s debugger client doesn&#39;t support the full range of commands, but
simple step and inspection is possible. By putting the statement <code>debugger;</code>
into the source code of your script, you will enable a breakpoint.
</p>
<p>For example, suppose <code>myscript.js</code> looked like this:
</p>
<pre><code>// myscript.js
x = 5;
setTimeout(function () {
debugger;
console.log(&quot;world&quot;);
}, 1000);
console.log(&quot;hello&quot;);</code></pre>
<p>Then once the debugger is run, it will break on line 4.
</p>
<pre><code>% node debug myscript.js
&lt; debugger listening on port 5858
connecting... ok
break in /home/indutny/Code/git/indutny/myscript.js:1
1 x = 5;
2 setTimeout(function () {
3 debugger;
debug&gt; cont
&lt; hello
break in /home/indutny/Code/git/indutny/myscript.js:3
1 x = 5;
2 setTimeout(function () {
3 debugger;
4 console.log(&quot;world&quot;);
5 }, 1000);
debug&gt; next
break in /home/indutny/Code/git/indutny/myscript.js:4
2 setTimeout(function () {
3 debugger;
4 console.log(&quot;world&quot;);
5 }, 1000);
6 console.log(&quot;hello&quot;);
debug&gt; repl
Press Ctrl + C to leave debug repl
&gt; x
5
&gt; 2+2
4
debug&gt; next
&lt; world
break in /home/indutny/Code/git/indutny/myscript.js:5
3 debugger;
4 console.log(&quot;world&quot;);
5 }, 1000);
6 console.log(&quot;hello&quot;);
7
debug&gt; quit
%</code></pre>
<p>The <code>repl</code> command allows you to evaluate code remotely. The <code>next</code> command
steps over to the next line. There are a few other commands available and more
to come. Type <code>help</code> to see others.
</p>
<h2>Watchers<span><a class="mark" href="#all_watchers" id="all_watchers">#</a></span></h2>
<p>You can watch expression and variable values while debugging your code.
On every breakpoint each expression from the watchers list will be evaluated
in the current context and displayed just before the breakpoint&#39;s source code
listing.
</p>
<p>To start watching an expression, type <code>watch(&quot;my_expression&quot;)</code>. <code>watchers</code>
prints the active watchers. To remove a watcher, type
<code>unwatch(&quot;my_expression&quot;)</code>.
</p>
<h2>Commands reference<span><a class="mark" href="#all_commands_reference" id="all_commands_reference">#</a></span></h2>
<h3>Stepping<span><a class="mark" href="#all_stepping" id="all_stepping">#</a></span></h3>
<ul>
<li><code>cont</code>, <code>c</code> - Continue execution</li>
<li><code>next</code>, <code>n</code> - Step next</li>
<li><code>step</code>, <code>s</code> - Step in</li>
<li><code>out</code>, <code>o</code> - Step out</li>
<li><code>pause</code> - Pause running code (like pause button in Developer Tools)</li>
</ul>
<h3>Breakpoints<span><a class="mark" href="#all_breakpoints" id="all_breakpoints">#</a></span></h3>
<div class="signature"><ul>
<li><code>setBreakpoint()</code>, <code>sb()</code> - Set breakpoint on current line</li>
<li><code>setBreakpoint(line)</code>, <code>sb(line)</code> - Set breakpoint on specific line</li>
<li><code>setBreakpoint(&#39;fn()&#39;)</code>, <code>sb(...)</code> - Set breakpoint on a first statement in
functions body</li>
<li><code>setBreakpoint(&#39;script.js&#39;, 1)</code>, <code>sb(...)</code> - Set breakpoint on first line of
script.js</li>
<li><code>clearBreakpoint</code>, <code>cb(...)</code> - Clear breakpoint</li>
</div></ul>
<p>It is also possible to set a breakpoint in a file (module) that
isn&#39;t loaded yet:
</p>
<pre><code>% ./node debug test/fixtures/break-in-module/main.js
&lt; debugger listening on port 5858
connecting to port 5858... ok
break in test/fixtures/break-in-module/main.js:1
1 var mod = require(&#39;./mod.js&#39;);
2 mod.hello();
3 mod.hello();
debug&gt; setBreakpoint(&#39;mod.js&#39;, 23)
Warning: script &#39;mod.js&#39; was not loaded yet.
1 var mod = require(&#39;./mod.js&#39;);
2 mod.hello();
3 mod.hello();
debug&gt; c
break in test/fixtures/break-in-module/mod.js:23
21
22 exports.hello = function() {
23 return &#39;hello from module&#39;;
24 };
25
debug&gt;</code></pre>
<h3>Info<span><a class="mark" href="#all_info" id="all_info">#</a></span></h3>
<div class="signature"><ul>
<li><code>backtrace</code>, <code>bt</code> - Print backtrace of current execution frame</li>
<li><code>list(5)</code> - List scripts source code with 5 line context (5 lines before and
after)</li>
<li><code>watch(expr)</code> - Add expression to watch list</li>
<li><code>unwatch(expr)</code> - Remove expression from watch list</li>
<li><code>watchers</code> - List all watchers and their values (automatically listed on each
breakpoint)</li>
<li><code>repl</code> - Open debugger&#39;s repl for evaluation in debugging script&#39;s context</li>
</div></ul>
<h3>Execution control<span><a class="mark" href="#all_execution_control" id="all_execution_control">#</a></span></h3>
<div class="signature"><ul>
<li><code>run</code> - Run script (automatically runs on debugger&#39;s start)</li>
<li><code>restart</code> - Restart script</li>
<li><code>kill</code> - Kill script</li>
</div></ul>
<h3>Various<span><a class="mark" href="#all_various" id="all_various">#</a></span></h3>
<div class="signature"><ul>
<li><code>scripts</code> - List all loaded scripts</li>
<li><code>version</code> - Display v8&#39;s version</li>
</div></ul>
<h2>Advanced Usage<span><a class="mark" href="#all_advanced_usage" id="all_advanced_usage">#</a></span></h2>
<p>The V8 debugger can be enabled and accessed either by starting Node with
the <code>--debug</code> command-line flag or by signaling an existing Node process
with <code>SIGUSR1</code>.
</p>
<p>Once a process has been set in debug mode with this it can be connected to
with the node debugger. Either connect to the <code>pid</code> or the URI to the debugger.
The syntax is:
</p>
<ul>
<li><code>node debug -p &lt;pid&gt;</code> - Connects to the process via the <code>pid</code></li>
<li>`node debug <URI> - Connects to the process via the URI such as localhost:5858</li>
</ul>
<h1>Cluster<span><a class="mark" href="#all_cluster" id="all_cluster">#</a></span></h1>
<pre class="api_stability_1">Stability: 1 - Experimental</pre><p>A single instance of Node runs in a single thread. To take advantage of
multi-core systems the user will sometimes want to launch a cluster of Node
processes to handle the load.
</p>
<p>The cluster module allows you to easily create child processes that
all share server ports.
</p>
<pre><code>var cluster = require(&#39;cluster&#39;);
var http = require(&#39;http&#39;);
var numCPUs = require(&#39;os&#39;).cpus().length;
if (cluster.isMaster) {
// Fork workers.
for (var i = 0; i &lt; numCPUs; i++) {
cluster.fork();
}
cluster.on(&#39;exit&#39;, function(worker, code, signal) {
console.log(&#39;worker &#39; + worker.process.pid + &#39; died&#39;);
});
} else {
// Workers can share any TCP connection
// In this case its a HTTP server
http.createServer(function(req, res) {
res.writeHead(200);
res.end(&quot;hello world\n&quot;);
}).listen(8000);
}</code></pre>
<p>Running node will now share port 8000 between the workers:
</p>
<pre><code>% NODE_DEBUG=cluster node server.js
23521,Master Worker 23524 online
23521,Master Worker 23526 online
23521,Master Worker 23523 online
23521,Master Worker 23528 online</code></pre>
<p>This feature was introduced recently, and may change in future versions.
Please try it out and provide feedback.
</p>
<p>Also note that, on Windows, it is not yet possible to set up a named pipe
server in a worker.
</p>
<h2>How It Works<span><a class="mark" href="#all_how_it_works" id="all_how_it_works">#</a></span></h2>
<!--type=misc-->
<p>The worker processes are spawned using the <code>child_process.fork</code> method,
so that they can communicate with the parent via IPC and pass server
handles back and forth.
</p>
<p>When you call <code>server.listen(...)</code> in a worker, it serializes the
arguments and passes the request to the master process. If the master
process already has a listening server matching the worker&#39;s
requirements, then it passes the handle to the worker. If it does not
already have a listening server matching that requirement, then it will
create one, and pass the handle to the worker.
</p>
<p>This causes potentially surprising behavior in three edge cases:
</p>
<ol>
<li><code>server.listen({fd: 7})</code> Because the message is passed to the master,
file descriptor 7 <strong>in the parent</strong> will be listened on, and the
handle passed to the worker, rather than listening to the worker&#39;s
idea of what the number 7 file descriptor references.</li>
<li><code>server.listen(handle)</code> Listening on handles explicitly will cause
the worker to use the supplied handle, rather than talk to the master
process. If the worker already has the handle, then it&#39;s presumed
that you know what you are doing.</li>
<li><code>server.listen(0)</code> Normally, this will cause servers to listen on a
random port. However, in a cluster, each worker will receive the
same &quot;random&quot; port each time they do <code>listen(0)</code>. In essence, the
port is random the first time, but predictable thereafter. If you
want to listen on a unique port, generate a port number based on the
cluster worker ID.</li>
</ol>
<p>When multiple processes are all <code>accept()</code>ing on the same underlying
resource, the operating system load-balances across them very
efficiently. There is no routing logic in Node.js, or in your program,
and no shared state between the workers. Therefore, it is important to
design your program such that it does not rely too heavily on in-memory
data objects for things like sessions and login.
</p>
<p>Because workers are all separate processes, they can be killed or
re-spawned depending on your program&#39;s needs, without affecting other
workers. As long as there are some workers still alive, the server will
continue to accept connections. Node does not automatically manage the
number of workers for you, however. It is your responsibility to manage
the worker pool for your application&#39;s needs.
</p>
<h2>cluster.settings<span><a class="mark" href="#all_cluster_settings" id="all_cluster_settings">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Object</span><ul>
<li><code>execArgv</code> <span class="type">Array</span> list of string arguments passed to the node executable.
(Default=<code>process.execArgv</code>)</li>
<li><code>exec</code> <span class="type">String</span> file path to worker file. (Default=<code>process.argv[1]</code>)</li>
<li><code>args</code> <span class="type">Array</span> string arguments passed to worker.
(Default=<code>process.argv.slice(2)</code>)</li>
<li><code>silent</code> <span class="type">Boolean</span> whether or not to send output to parent&#39;s stdio.
(Default=<code>false</code>)</li>
</ul>
</li>
</div></ul>
<p>After calling <code>.setupMaster()</code> (or <code>.fork()</code>) this settings object will contain
the settings, including the default values.
</p>
<p>It is effectively frozen after being set, because <code>.setupMaster()</code> can
only be called once.
</p>
<p>This object is not supposed to be changed or set manually, by you.
</p>
<h2>cluster.isMaster<span><a class="mark" href="#all_cluster_ismaster" id="all_cluster_ismaster">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Boolean</span></li>
</div></ul>
<p>True if the process is a master. This is determined
by the <code>process.env.NODE_UNIQUE_ID</code>. If <code>process.env.NODE_UNIQUE_ID</code> is
undefined, then <code>isMaster</code> is <code>true</code>.
</p>
<h2>cluster.isWorker<span><a class="mark" href="#all_cluster_isworker" id="all_cluster_isworker">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Boolean</span></li>
</div></ul>
<p>True if the process is not a master (it is the negation of <code>cluster.isMaster</code>).
</p>
<h2>Event: &#39;fork&#39;<span><a class="mark" href="#all_event_fork" id="all_event_fork">#</a></span></h2>
<div class="signature"><ul>
<li><code>worker</code> <span class="type">Worker object</span></li>
</div></ul>
<p>When a new worker is forked the cluster module will emit a &#39;fork&#39; event.
This can be used to log worker activity, and create you own timeout.
</p>
<pre><code>var timeouts = [];
function errorMsg() {
console.error(&quot;Something must be wrong with the connection ...&quot;);
}
cluster.on(&#39;fork&#39;, function(worker) {
timeouts[worker.id] = setTimeout(errorMsg, 2000);
});
cluster.on(&#39;listening&#39;, function(worker, address) {
clearTimeout(timeouts[worker.id]);
});
cluster.on(&#39;exit&#39;, function(worker, code, signal) {
clearTimeout(timeouts[worker.id]);
errorMsg();
});</code></pre>
<h2>Event: &#39;online&#39;<span><a class="mark" href="#all_event_online" id="all_event_online">#</a></span></h2>
<div class="signature"><ul>
<li><code>worker</code> <span class="type">Worker object</span></li>
</div></ul>
<p>After forking a new worker, the worker should respond with an online message.
When the master receives an online message it will emit this event.
The difference between &#39;fork&#39; and &#39;online&#39; is that fork is emitted when the
master forks a worker, and &#39;online&#39; is emitted when the worker is running.
</p>
<pre><code>cluster.on(&#39;online&#39;, function(worker) {
console.log(&quot;Yay, the worker responded after it was forked&quot;);
});</code></pre>
<h2>Event: &#39;listening&#39;<span><a class="mark" href="#all_event_listening_2" id="all_event_listening_2">#</a></span></h2>
<div class="signature"><ul>
<li><code>worker</code> <span class="type">Worker object</span></li>
<li><code>address</code> <span class="type">Object</span></li>
</div></ul>
<p>After calling <code>listen()</code> from a worker, when the &#39;listening&#39; event is emitted on
the server, a listening event will also be emitted on <code>cluster</code> in the master.
</p>
<p>The event handler is executed with two arguments, the <code>worker</code> contains the worker
object and the <code>address</code> object contains the following connection properties:
<code>address</code>, <code>port</code> and <code>addressType</code>. This is very useful if the worker is listening
on more than one address.
</p>
<pre><code>cluster.on(&#39;listening&#39;, function(worker, address) {
console.log(&quot;A worker is now connected to &quot; + address.address + &quot;:&quot; + address.port);
});</code></pre>
<p>The <code>addressType</code> is one of:
</p>
<ul>
<li><code>4</code> (TCPv4)</li>
<li><code>6</code> (TCPv6)</li>
<li><code>-1</code> (unix domain socket)</li>
<li><code>&quot;udp4&quot;</code> or <code>&quot;udp6&quot;</code> (UDP v4 or v6)</li>
</ul>
<h2>Event: &#39;disconnect&#39;<span><a class="mark" href="#all_event_disconnect_1" id="all_event_disconnect_1">#</a></span></h2>
<div class="signature"><ul>
<li><code>worker</code> <span class="type">Worker object</span></li>
</div></ul>
<p>Emitted after the worker IPC channel has disconnected. This can occur when a
worker exits gracefully, is killed, or is disconnected manually (such as with
worker.disconnect()).
</p>
<p>There may be a delay between the <code>disconnect</code> and <code>exit</code> events. These events
can be used to detect if the process is stuck in a cleanup or if there are
long-living connections.
</p>
<pre><code>cluster.on(&#39;disconnect&#39;, function(worker) {
console.log(&#39;The worker #&#39; + worker.id + &#39; has disconnected&#39;);
});</code></pre>
<h2>Event: &#39;exit&#39;<span><a class="mark" href="#all_event_exit_3" id="all_event_exit_3">#</a></span></h2>
<div class="signature"><ul>
<li><code>worker</code> <span class="type">Worker object</span></li>
<li><code>code</code> <span class="type">Number</span> the exit code, if it exited normally.</li>
<li><code>signal</code> <span class="type">String</span> the name of the signal (eg. <code>&#39;SIGHUP&#39;</code>) that caused
the process to be killed.</li>
</div></ul>
<p>When any of the workers die the cluster module will emit the &#39;exit&#39; event.
</p>
<p>This can be used to restart the worker by calling <code>.fork()</code> again.
</p>
<pre><code>cluster.on(&#39;exit&#39;, function(worker, code, signal) {
console.log(&#39;worker %d died (%s). restarting...&#39;,
worker.process.pid, signal || code);
cluster.fork();
});</code></pre>
<p>See <a href="child_process.html#child_process_event_exit">child_process event: &#39;exit&#39;</a>.
</p>
<h2>Event: &#39;setup&#39;<span><a class="mark" href="#all_event_setup" id="all_event_setup">#</a></span></h2>
<p>Emitted the first time that <code>.setupMaster()</code> is called.
</p>
<h2>cluster.setupMaster([settings])<span><a class="mark" href="#all_cluster_setupmaster_settings" id="all_cluster_setupmaster_settings">#</a></span></h2>
<div class="signature"><ul>
<li><code>settings</code> <span class="type">Object</span><ul>
<li><code>exec</code> <span class="type">String</span> file path to worker file. (Default=<code>process.argv[1]</code>)</li>
<li><code>args</code> <span class="type">Array</span> string arguments passed to worker.
(Default=<code>process.argv.slice(2)</code>)</li>
<li><code>silent</code> <span class="type">Boolean</span> whether or not to send output to parent&#39;s stdio.
(Default=<code>false</code>)</li>
</ul>
</li>
</div></ul>
<p><code>setupMaster</code> is used to change the default &#39;fork&#39; behavior. Once called,
the settings will be present in <code>cluster.settings</code>.
</p>
<p>Note that:
</p>
<ul>
<li>Only the first call to <code>.setupMaster()</code> has any effect, subsequent calls are
ignored</li>
<li>That because of the above, the <em>only</em> attribute of a worker that may be
customized per-worker is the <code>env</code> passed to <code>.fork()</code></li>
<li><code>.fork()</code> calls <code>.setupMaster()</code> internally to establish the defaults, so to
have any effect, <code>.setupMaster()</code> must be called <em>before</em> any calls to
<code>.fork()</code></li>
</ul>
<p>Example:
</p>
<pre><code>var cluster = require(&quot;cluster&quot;);
cluster.setupMaster({
exec : &quot;worker.js&quot;,
args : [&quot;--use&quot;, &quot;https&quot;],
silent : true
});
cluster.fork();</code></pre>
<p>This can only be called from the master process.
</p>
<h2>cluster.fork([env])<span><a class="mark" href="#all_cluster_fork_env" id="all_cluster_fork_env">#</a></span></h2>
<div class="signature"><ul>
<li><code>env</code> <span class="type">Object</span> Key/value pairs to add to worker process environment.</li>
<li>return <span class="type">Worker object</span></li>
</div></ul>
<p>Spawn a new worker process.
</p>
<p>This can only be called from the master process.
</p>
<h2>cluster.disconnect([callback])<span><a class="mark" href="#all_cluster_disconnect_callback" id="all_cluster_disconnect_callback">#</a></span></h2>
<div class="signature"><ul>
<li><code>callback</code> <span class="type">Function</span> called when all workers are disconnected and handles are
closed</li>
</div></ul>
<p>Calls <code>.disconnect()</code> on each worker in <code>cluster.workers</code>.
</p>
<p>When they are disconnected all internal handles will be closed, allowing the
master process to die gracefully if no other event is waiting.
</p>
<p>The method takes an optional callback argument which will be called when finished.
</p>
<p>This can only be called from the master process.
</p>
<h2>cluster.worker<span><a class="mark" href="#all_cluster_worker" id="all_cluster_worker">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<p>A reference to the current worker object. Not available in the master process.
</p>
<pre><code>var cluster = require(&#39;cluster&#39;);
if (cluster.isMaster) {
console.log(&#39;I am master&#39;);
cluster.fork();
cluster.fork();
} else if (cluster.isWorker) {
console.log(&#39;I am worker #&#39; + cluster.worker.id);
}</code></pre>
<h2>cluster.workers<span><a class="mark" href="#all_cluster_workers" id="all_cluster_workers">#</a></span></h2>
<div class="signature"><ul>
<li><span class="type">Object</span></li>
</div></ul>
<p>A hash that stores the active worker objects, keyed by <code>id</code> field. Makes it
easy to loop through all the workers. It is only available in the master
process.
</p>
<p>A worker is removed from cluster.workers just before the <code>&#39;disconnect&#39;</code> or
<code>&#39;exit&#39;</code> event is emitted.
</p>
<pre><code>// Go through all workers
function eachWorker(callback) {
for (var id in cluster.workers) {
callback(cluster.workers[id]);
}
}
eachWorker(function(worker) {
worker.send(&#39;big announcement to all workers&#39;);
});</code></pre>
<p>Should you wish to reference a worker over a communication channel, using
the worker&#39;s unique id is the easiest way to find the worker.
</p>
<pre><code>socket.on(&#39;data&#39;, function(id) {
var worker = cluster.workers[id];
});</code></pre>
<h2>Class: Worker<span><a class="mark" href="#all_class_worker" id="all_class_worker">#</a></span></h2>
<p>A Worker object contains all public information and method about a worker.
In the master it can be obtained using <code>cluster.workers</code>. In a worker
it can be obtained using <code>cluster.worker</code>.
</p>
<h3>worker.id<span><a class="mark" href="#all_worker_id" id="all_worker_id">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">String</span></li>
</div></ul>
<p>Each new worker is given its own unique id, this id is stored in the
<code>id</code>.
</p>
<p>While a worker is alive, this is the key that indexes it in
cluster.workers
</p>
<h3>worker.process<span><a class="mark" href="#all_worker_process" id="all_worker_process">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">ChildProcess object</span></li>
</div></ul>
<p>All workers are created using <code>child_process.fork()</code>, the returned object
from this function is stored as <code>.process</code>. In a worker, the global <code>process</code>
is stored.
</p>
<p>See: <a href="child_process.html#child_process_child_process_fork_modulepath_args_options">Child Process module</a>
</p>
<p>Note that workers will call <code>process.exit(0)</code> if the <code>&#39;disconnect&#39;</code> event occurs
on <code>process</code> and <code>.suicide</code> is not <code>true</code>. This protects against accidental
disconnection.
</p>
<h3>worker.suicide<span><a class="mark" href="#all_worker_suicide" id="all_worker_suicide">#</a></span></h3>
<div class="signature"><ul>
<li><span class="type">Boolean</span></li>
</div></ul>
<p>Set by calling <code>.kill()</code> or <code>.disconnect()</code>, until then it is <code>undefined</code>.
</p>
<p>The boolean <code>worker.suicide</code> lets you distinguish between voluntary and accidental
exit, the master may choose not to respawn a worker based on this value.
</p>
<pre><code>cluster.on(&#39;exit&#39;, function(worker, code, signal) {
if (worker.suicide === true) {
console.log(&#39;Oh, it was just suicide\&#39; – no need to worry&#39;).
}
});
// kill worker
worker.kill();</code></pre>
<h3>worker.send(message, [sendHandle])<span><a class="mark" href="#all_worker_send_message_sendhandle" id="all_worker_send_message_sendhandle">#</a></span></h3>
<div class="signature"><ul>
<li><code>message</code> <span class="type">Object</span></li>
<li><code>sendHandle</code> <span class="type">Handle object</span></li>
</div></ul>
<p>This function is equal to the send methods provided by
<code>child_process.fork()</code>. In the master you should use this function to
send a message to a specific worker.
</p>
<p>In a worker you can also use <code>process.send(message)</code>, it is the same function.
</p>
<p>This example will echo back all messages from the master:
</p>
<pre><code>if (cluster.isMaster) {
var worker = cluster.fork();
worker.send(&#39;hi there&#39;);
} else if (cluster.isWorker) {
process.on(&#39;message&#39;, function(msg) {
process.send(msg);
});
}</code></pre>
<h3>worker.kill([signal=&#39;SIGTERM&#39;])<span><a class="mark" href="#all_worker_kill_signal_sigterm" id="all_worker_kill_signal_sigterm">#</a></span></h3>
<div class="signature"><ul>
<li><code>signal</code> <span class="type">String</span> Name of the kill signal to send to the worker
process.</li>
</div></ul>
<p>This function will kill the worker. In the master, it does this by disconnecting
the <code>worker.process</code>, and once disconnected, killing with <code>signal</code>. In the
worker, it does it by disconnecting the channel, and then exiting with code <code>0</code>.
</p>
<p>Causes <code>.suicide</code> to be set.
</p>
<p>This method is aliased as <code>worker.destroy()</code> for backwards compatibility.
</p>
<p>Note that in a worker, <code>process.kill()</code> exists, but it is not this function,
it is <a href="process.html#process_process_kill_pid_signal">kill</a>.
</p>
<h3>worker.disconnect()<span><a class="mark" href="#all_worker_disconnect" id="all_worker_disconnect">#</a></span></h3>
<p>In a worker, this function will close all servers, wait for the &#39;close&#39; event on
those servers, and then disconnect the IPC channel.
</p>
<p>In the master, an internal message is sent to the worker causing it to call
<code>.disconnect()</code> on itself.
</p>
<p>Causes <code>.suicide</code> to be set.
</p>
<p>Note that after a server is closed, it will no longer accept new connections,
but connections may be accepted by any other listening worker. Existing
connections will be allowed to close as usual. When no more connections exist,
see <a href="net.html#net_event_close">server.close()</a>, the IPC channel to the worker
will close allowing it to die gracefully.
</p>
<p>The above applies <em>only</em> to server connections, client connections are not
automatically closed by workers, and disconnect does not wait for them to close
before exiting.
</p>
<p>Note that in a worker, <code>process.disconnect</code> exists, but it is not this function,
it is <a href="child_process.html#child_process_child_disconnect">disconnect</a>.
</p>
<p>Because long living server connections may block workers from disconnecting, it
may be useful to send a message, so application specific actions may be taken to
close them. It also may be useful to implement a timeout, killing a worker if
the <code>disconnect</code> event has not been emitted after some time.
</p>
<pre><code>if (cluster.isMaster) {
var worker = cluster.fork();
var timeout;
worker.on(&#39;listening&#39;, function(address) {
worker.send(&#39;shutdown&#39;);
worker.disconnect();
timeout = setTimeout(function() {
worker.kill();
}, 2000);
});
worker.on(&#39;disconnect&#39;, function() {
clearTimeout(timeout);
});
} else if (cluster.isWorker) {
var net = require(&#39;net&#39;);
var server = net.createServer(function(socket) {
// connections never end
});
server.listen(8000);
process.on(&#39;message&#39;, function(msg) {
if(msg === &#39;shutdown&#39;) {
// initiate graceful close of any connections to server
}
});
}</code></pre>
<h3>Event: &#39;message&#39;<span><a class="mark" href="#all_event_message_2" id="all_event_message_2">#</a></span></h3>
<div class="signature"><ul>
<li><code>message</code> <span class="type">Object</span></li>
</div></ul>
<p>This event is the same as the one provided by <code>child_process.fork()</code>.
</p>
<p>In a worker you can also use <code>process.on(&#39;message&#39;)</code>.
</p>
<p>As an example, here is a cluster that keeps count of the number of requests
in the master process using the message system:
</p>
<pre><code>var cluster = require(&#39;cluster&#39;);
var http = require(&#39;http&#39;);
if (cluster.isMaster) {
// Keep track of http requests
var numReqs = 0;
setInterval(function() {
console.log(&quot;numReqs =&quot;, numReqs);
}, 1000);
// Count requestes
function messageHandler(msg) {
if (msg.cmd &amp;&amp; msg.cmd == &#39;notifyRequest&#39;) {
numReqs += 1;
}
}
// Start workers and listen for messages containing notifyRequest
var numCPUs = require(&#39;os&#39;).cpus().length;
for (var i = 0; i &lt; numCPUs; i++) {
cluster.fork();
}
Object.keys(cluster.workers).forEach(function(id) {
cluster.workers[id].on(&#39;message&#39;, messageHandler);
});
} else {
// Worker processes have a http server.
http.Server(function(req, res) {
res.writeHead(200);
res.end(&quot;hello world\n&quot;);
// notify master about the request
process.send({ cmd: &#39;notifyRequest&#39; });
}).listen(8000);
}</code></pre>
<h3>Event: &#39;online&#39;<span><a class="mark" href="#all_event_online_1" id="all_event_online_1">#</a></span></h3>
<p>Similar to the <code>cluster.on(&#39;online&#39;)</code> event, but specific to this worker.
</p>
<pre><code>cluster.fork().on(&#39;online&#39;, function() {
// Worker is online
});</code></pre>
<p>It is not emitted in the worker.
</p>
<h3>Event: &#39;listening&#39;<span><a class="mark" href="#all_event_listening_3" id="all_event_listening_3">#</a></span></h3>
<div class="signature"><ul>
<li><code>address</code> <span class="type">Object</span></li>
</div></ul>
<p>Similar to the <code>cluster.on(&#39;listening&#39;)</code> event, but specific to this worker.
</p>
<pre><code>cluster.fork().on(&#39;listening&#39;, function(address) {
// Worker is listening
});</code></pre>
<p>It is not emitted in the worker.
</p>
<h3>Event: &#39;disconnect&#39;<span><a class="mark" href="#all_event_disconnect_2" id="all_event_disconnect_2">#</a></span></h3>
<p>Similar to the <code>cluster.on(&#39;disconnect&#39;)</code> event, but specfic to this worker.
</p>
<pre><code>cluster.fork().on(&#39;disconnect&#39;, function() {
// Worker has disconnected
});</code></pre>
<h3>Event: &#39;exit&#39;<span><a class="mark" href="#all_event_exit_4" id="all_event_exit_4">#</a></span></h3>
<div class="signature"><ul>
<li><code>code</code> <span class="type">Number</span> the exit code, if it exited normally.</li>
<li><code>signal</code> <span class="type">String</span> the name of the signal (eg. <code>&#39;SIGHUP&#39;</code>) that caused
the process to be killed.</li>
</div></ul>
<p>Similar to the <code>cluster.on(&#39;exit&#39;)</code> event, but specific to this worker.
</p>
<pre><code>var worker = cluster.fork();
worker.on(&#39;exit&#39;, function(code, signal) {
if( signal ) {
console.log(&quot;worker was killed by signal: &quot;+signal);
} else if( code !== 0 ) {
console.log(&quot;worker exited with error code: &quot;+code);
} else {
console.log(&quot;worker success!&quot;);
}
});</code></pre>
<h3>Event: &#39;error&#39;<span><a class="mark" href="#all_event_error_7" id="all_event_error_7">#</a></span></h3>
<p>This event is the same as the one provided by <code>child_process.fork()</code>.
</p>
<p>In a worker you can also use <code>process.on(&#39;error&#39;)</code>.
</p>
</div>
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