1 | # ws: a Node.js WebSocket library
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2 |
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3 | [![Version npm](https://img.shields.io/npm/v/ws.svg?logo=npm)](https://www.npmjs.com/package/ws)
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4 | [![CI](https://img.shields.io/github/actions/workflow/status/websockets/ws/ci.yml?branch=master&label=CI&logo=github)](https://github.com/websockets/ws/actions?query=workflow%3ACI+branch%3Amaster)
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5 | [![Coverage Status](https://img.shields.io/coveralls/websockets/ws/master.svg?logo=coveralls)](https://coveralls.io/github/websockets/ws)
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6 |
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7 | ws is a simple to use, blazing fast, and thoroughly tested WebSocket client and
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8 | server implementation.
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9 |
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10 | Passes the quite extensive Autobahn test suite: [server][server-report],
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11 | [client][client-report].
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12 |
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13 | **Note**: This module does not work in the browser. The client in the docs is a
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14 | reference to a backend with the role of a client in the WebSocket communication.
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15 | Browser clients must use the native
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16 | [`WebSocket`](https://developer.mozilla.org/en-US/docs/Web/API/WebSocket)
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17 | object. To make the same code work seamlessly on Node.js and the browser, you
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18 | can use one of the many wrappers available on npm, like
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19 | [isomorphic-ws](https://github.com/heineiuo/isomorphic-ws).
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20 |
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21 | ## Table of Contents
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22 |
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23 | - [Protocol support](#protocol-support)
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24 | - [Installing](#installing)
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25 | - [Opt-in for performance](#opt-in-for-performance)
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26 | - [Legacy opt-in for performance](#legacy-opt-in-for-performance)
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27 | - [API docs](#api-docs)
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28 | - [WebSocket compression](#websocket-compression)
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29 | - [Usage examples](#usage-examples)
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30 | - [Sending and receiving text data](#sending-and-receiving-text-data)
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31 | - [Sending binary data](#sending-binary-data)
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32 | - [Simple server](#simple-server)
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33 | - [External HTTP/S server](#external-https-server)
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34 | - [Multiple servers sharing a single HTTP/S server](#multiple-servers-sharing-a-single-https-server)
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35 | - [Client authentication](#client-authentication)
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36 | - [Server broadcast](#server-broadcast)
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37 | - [Round-trip time](#round-trip-time)
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38 | - [Use the Node.js streams API](#use-the-nodejs-streams-api)
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39 | - [Other examples](#other-examples)
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40 | - [FAQ](#faq)
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41 | - [How to get the IP address of the client?](#how-to-get-the-ip-address-of-the-client)
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42 | - [How to detect and close broken connections?](#how-to-detect-and-close-broken-connections)
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43 | - [How to connect via a proxy?](#how-to-connect-via-a-proxy)
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44 | - [Changelog](#changelog)
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45 | - [License](#license)
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46 |
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47 | ## Protocol support
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48 |
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49 | - **HyBi drafts 07-12** (Use the option `protocolVersion: 8`)
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50 | - **HyBi drafts 13-17** (Current default, alternatively option
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51 | `protocolVersion: 13`)
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52 |
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53 | ## Installing
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54 |
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55 | ```
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56 | npm install ws
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57 | ```
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58 |
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59 | ### Opt-in for performance
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60 |
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61 | [bufferutil][] is an optional module that can be installed alongside the ws
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62 | module:
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63 |
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64 | ```
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65 | npm install --save-optional bufferutil
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66 | ```
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67 |
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68 | This is a binary addon that improves the performance of certain operations such
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69 | as masking and unmasking the data payload of the WebSocket frames. Prebuilt
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70 | binaries are available for the most popular platforms, so you don't necessarily
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71 | need to have a C++ compiler installed on your machine.
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72 |
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73 | To force ws to not use bufferutil, use the
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74 | [`WS_NO_BUFFER_UTIL`](./doc/ws.md#ws_no_buffer_util) environment variable. This
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75 | can be useful to enhance security in systems where a user can put a package in
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76 | the package search path of an application of another user, due to how the
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77 | Node.js resolver algorithm works.
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78 |
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79 | #### Legacy opt-in for performance
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80 |
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81 | If you are running on an old version of Node.js (prior to v18.14.0), ws also
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82 | supports the [utf-8-validate][] module:
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83 |
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84 | ```
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85 | npm install --save-optional utf-8-validate
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86 | ```
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87 |
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88 | This contains a binary polyfill for [`buffer.isUtf8()`][].
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89 |
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90 | To force ws not to use utf-8-validate, use the
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91 | [`WS_NO_UTF_8_VALIDATE`](./doc/ws.md#ws_no_utf_8_validate) environment variable.
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92 |
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93 | ## API docs
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94 |
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95 | See [`/doc/ws.md`](./doc/ws.md) for Node.js-like documentation of ws classes and
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96 | utility functions.
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97 |
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98 | ## WebSocket compression
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99 |
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100 | ws supports the [permessage-deflate extension][permessage-deflate] which enables
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101 | the client and server to negotiate a compression algorithm and its parameters,
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102 | and then selectively apply it to the data payloads of each WebSocket message.
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103 |
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104 | The extension is disabled by default on the server and enabled by default on the
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105 | client. It adds a significant overhead in terms of performance and memory
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106 | consumption so we suggest to enable it only if it is really needed.
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107 |
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108 | Note that Node.js has a variety of issues with high-performance compression,
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109 | where increased concurrency, especially on Linux, can lead to [catastrophic
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110 | memory fragmentation][node-zlib-bug] and slow performance. If you intend to use
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111 | permessage-deflate in production, it is worthwhile to set up a test
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112 | representative of your workload and ensure Node.js/zlib will handle it with
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113 | acceptable performance and memory usage.
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114 |
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115 | Tuning of permessage-deflate can be done via the options defined below. You can
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116 | also use `zlibDeflateOptions` and `zlibInflateOptions`, which is passed directly
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117 | into the creation of [raw deflate/inflate streams][node-zlib-deflaterawdocs].
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118 |
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119 | See [the docs][ws-server-options] for more options.
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120 |
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121 | ```js
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122 | import WebSocket, { WebSocketServer } from 'ws';
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123 |
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124 | const wss = new WebSocketServer({
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125 | port: 8080,
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126 | perMessageDeflate: {
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127 | zlibDeflateOptions: {
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128 | // See zlib defaults.
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129 | chunkSize: 1024,
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130 | memLevel: 7,
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131 | level: 3
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132 | },
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133 | zlibInflateOptions: {
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134 | chunkSize: 10 * 1024
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135 | },
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136 | // Other options settable:
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137 | clientNoContextTakeover: true, // Defaults to negotiated value.
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138 | serverNoContextTakeover: true, // Defaults to negotiated value.
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139 | serverMaxWindowBits: 10, // Defaults to negotiated value.
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140 | // Below options specified as default values.
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141 | concurrencyLimit: 10, // Limits zlib concurrency for perf.
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142 | threshold: 1024 // Size (in bytes) below which messages
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143 | // should not be compressed if context takeover is disabled.
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144 | }
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145 | });
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146 | ```
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147 |
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148 | The client will only use the extension if it is supported and enabled on the
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149 | server. To always disable the extension on the client, set the
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150 | `perMessageDeflate` option to `false`.
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151 |
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152 | ```js
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153 | import WebSocket from 'ws';
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154 |
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155 | const ws = new WebSocket('ws://www.host.com/path', {
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156 | perMessageDeflate: false
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157 | });
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158 | ```
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159 |
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160 | ## Usage examples
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161 |
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162 | ### Sending and receiving text data
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163 |
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164 | ```js
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165 | import WebSocket from 'ws';
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166 |
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167 | const ws = new WebSocket('ws://www.host.com/path');
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168 |
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169 | ws.on('error', console.error);
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170 |
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171 | ws.on('open', function open() {
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172 | ws.send('something');
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173 | });
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174 |
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175 | ws.on('message', function message(data) {
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176 | console.log('received: %s', data);
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177 | });
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178 | ```
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179 |
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180 | ### Sending binary data
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181 |
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182 | ```js
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183 | import WebSocket from 'ws';
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184 |
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185 | const ws = new WebSocket('ws://www.host.com/path');
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186 |
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187 | ws.on('error', console.error);
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188 |
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189 | ws.on('open', function open() {
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190 | const array = new Float32Array(5);
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191 |
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192 | for (var i = 0; i < array.length; ++i) {
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193 | array[i] = i / 2;
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194 | }
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195 |
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196 | ws.send(array);
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197 | });
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198 | ```
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199 |
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200 | ### Simple server
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201 |
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202 | ```js
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203 | import { WebSocketServer } from 'ws';
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204 |
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205 | const wss = new WebSocketServer({ port: 8080 });
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206 |
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207 | wss.on('connection', function connection(ws) {
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208 | ws.on('error', console.error);
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209 |
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210 | ws.on('message', function message(data) {
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211 | console.log('received: %s', data);
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212 | });
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213 |
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214 | ws.send('something');
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215 | });
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216 | ```
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217 |
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218 | ### External HTTP/S server
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219 |
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220 | ```js
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221 | import { createServer } from 'https';
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222 | import { readFileSync } from 'fs';
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223 | import { WebSocketServer } from 'ws';
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224 |
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225 | const server = createServer({
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226 | cert: readFileSync('/path/to/cert.pem'),
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227 | key: readFileSync('/path/to/key.pem')
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228 | });
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229 | const wss = new WebSocketServer({ server });
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230 |
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231 | wss.on('connection', function connection(ws) {
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232 | ws.on('error', console.error);
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233 |
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234 | ws.on('message', function message(data) {
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235 | console.log('received: %s', data);
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236 | });
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237 |
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238 | ws.send('something');
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239 | });
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240 |
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241 | server.listen(8080);
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242 | ```
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243 |
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244 | ### Multiple servers sharing a single HTTP/S server
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245 |
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246 | ```js
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247 | import { createServer } from 'http';
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248 | import { WebSocketServer } from 'ws';
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249 |
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250 | const server = createServer();
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251 | const wss1 = new WebSocketServer({ noServer: true });
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252 | const wss2 = new WebSocketServer({ noServer: true });
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253 |
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254 | wss1.on('connection', function connection(ws) {
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255 | ws.on('error', console.error);
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256 |
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257 | // ...
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258 | });
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259 |
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260 | wss2.on('connection', function connection(ws) {
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261 | ws.on('error', console.error);
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262 |
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263 | // ...
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264 | });
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265 |
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266 | server.on('upgrade', function upgrade(request, socket, head) {
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267 | const { pathname } = new URL(request.url, 'wss://base.url');
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268 |
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269 | if (pathname === '/foo') {
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270 | wss1.handleUpgrade(request, socket, head, function done(ws) {
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271 | wss1.emit('connection', ws, request);
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272 | });
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273 | } else if (pathname === '/bar') {
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274 | wss2.handleUpgrade(request, socket, head, function done(ws) {
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275 | wss2.emit('connection', ws, request);
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276 | });
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277 | } else {
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278 | socket.destroy();
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279 | }
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280 | });
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281 |
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282 | server.listen(8080);
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283 | ```
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284 |
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285 | ### Client authentication
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286 |
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287 | ```js
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288 | import { createServer } from 'http';
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289 | import { WebSocketServer } from 'ws';
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290 |
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291 | function onSocketError(err) {
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292 | console.error(err);
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293 | }
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294 |
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295 | const server = createServer();
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296 | const wss = new WebSocketServer({ noServer: true });
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297 |
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298 | wss.on('connection', function connection(ws, request, client) {
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299 | ws.on('error', console.error);
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300 |
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301 | ws.on('message', function message(data) {
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302 | console.log(`Received message ${data} from user ${client}`);
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303 | });
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304 | });
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305 |
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306 | server.on('upgrade', function upgrade(request, socket, head) {
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307 | socket.on('error', onSocketError);
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308 |
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309 | // This function is not defined on purpose. Implement it with your own logic.
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310 | authenticate(request, function next(err, client) {
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311 | if (err || !client) {
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312 | socket.write('HTTP/1.1 401 Unauthorized\r\n\r\n');
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313 | socket.destroy();
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314 | return;
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315 | }
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316 |
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317 | socket.removeListener('error', onSocketError);
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318 |
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319 | wss.handleUpgrade(request, socket, head, function done(ws) {
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320 | wss.emit('connection', ws, request, client);
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321 | });
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322 | });
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323 | });
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324 |
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325 | server.listen(8080);
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326 | ```
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327 |
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328 | Also see the provided [example][session-parse-example] using `express-session`.
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329 |
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330 | ### Server broadcast
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331 |
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332 | A client WebSocket broadcasting to all connected WebSocket clients, including
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333 | itself.
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334 |
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335 | ```js
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336 | import WebSocket, { WebSocketServer } from 'ws';
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337 |
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338 | const wss = new WebSocketServer({ port: 8080 });
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339 |
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340 | wss.on('connection', function connection(ws) {
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341 | ws.on('error', console.error);
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342 |
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343 | ws.on('message', function message(data, isBinary) {
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344 | wss.clients.forEach(function each(client) {
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345 | if (client.readyState === WebSocket.OPEN) {
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346 | client.send(data, { binary: isBinary });
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347 | }
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348 | });
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349 | });
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350 | });
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351 | ```
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352 |
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353 | A client WebSocket broadcasting to every other connected WebSocket clients,
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354 | excluding itself.
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355 |
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356 | ```js
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357 | import WebSocket, { WebSocketServer } from 'ws';
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358 |
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359 | const wss = new WebSocketServer({ port: 8080 });
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360 |
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361 | wss.on('connection', function connection(ws) {
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362 | ws.on('error', console.error);
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363 |
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364 | ws.on('message', function message(data, isBinary) {
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365 | wss.clients.forEach(function each(client) {
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366 | if (client !== ws && client.readyState === WebSocket.OPEN) {
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367 | client.send(data, { binary: isBinary });
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368 | }
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369 | });
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370 | });
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371 | });
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372 | ```
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373 |
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374 | ### Round-trip time
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375 |
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376 | ```js
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377 | import WebSocket from 'ws';
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378 |
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379 | const ws = new WebSocket('wss://websocket-echo.com/');
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380 |
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381 | ws.on('error', console.error);
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382 |
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383 | ws.on('open', function open() {
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384 | console.log('connected');
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385 | ws.send(Date.now());
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386 | });
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387 |
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388 | ws.on('close', function close() {
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389 | console.log('disconnected');
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390 | });
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391 |
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392 | ws.on('message', function message(data) {
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393 | console.log(`Round-trip time: ${Date.now() - data} ms`);
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394 |
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395 | setTimeout(function timeout() {
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396 | ws.send(Date.now());
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397 | }, 500);
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398 | });
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399 | ```
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400 |
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401 | ### Use the Node.js streams API
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402 |
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403 | ```js
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404 | import WebSocket, { createWebSocketStream } from 'ws';
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405 |
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406 | const ws = new WebSocket('wss://websocket-echo.com/');
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407 |
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408 | const duplex = createWebSocketStream(ws, { encoding: 'utf8' });
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409 |
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410 | duplex.on('error', console.error);
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411 |
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412 | duplex.pipe(process.stdout);
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413 | process.stdin.pipe(duplex);
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414 | ```
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415 |
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416 | ### Other examples
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417 |
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418 | For a full example with a browser client communicating with a ws server, see the
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419 | examples folder.
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420 |
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421 | Otherwise, see the test cases.
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422 |
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423 | ## FAQ
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424 |
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425 | ### How to get the IP address of the client?
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426 |
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427 | The remote IP address can be obtained from the raw socket.
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428 |
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429 | ```js
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430 | import { WebSocketServer } from 'ws';
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431 |
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432 | const wss = new WebSocketServer({ port: 8080 });
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433 |
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434 | wss.on('connection', function connection(ws, req) {
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435 | const ip = req.socket.remoteAddress;
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436 |
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437 | ws.on('error', console.error);
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438 | });
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439 | ```
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440 |
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441 | When the server runs behind a proxy like NGINX, the de-facto standard is to use
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442 | the `X-Forwarded-For` header.
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443 |
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444 | ```js
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445 | wss.on('connection', function connection(ws, req) {
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446 | const ip = req.headers['x-forwarded-for'].split(',')[0].trim();
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447 |
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448 | ws.on('error', console.error);
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449 | });
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450 | ```
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451 |
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452 | ### How to detect and close broken connections?
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453 |
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454 | Sometimes, the link between the server and the client can be interrupted in a
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455 | way that keeps both the server and the client unaware of the broken state of the
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456 | connection (e.g. when pulling the cord).
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457 |
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458 | In these cases, ping messages can be used as a means to verify that the remote
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459 | endpoint is still responsive.
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460 |
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461 | ```js
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462 | import { WebSocketServer } from 'ws';
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463 |
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464 | function heartbeat() {
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465 | this.isAlive = true;
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466 | }
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467 |
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468 | const wss = new WebSocketServer({ port: 8080 });
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469 |
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470 | wss.on('connection', function connection(ws) {
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471 | ws.isAlive = true;
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472 | ws.on('error', console.error);
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473 | ws.on('pong', heartbeat);
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474 | });
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475 |
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476 | const interval = setInterval(function ping() {
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477 | wss.clients.forEach(function each(ws) {
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478 | if (ws.isAlive === false) return ws.terminate();
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479 |
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480 | ws.isAlive = false;
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481 | ws.ping();
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482 | });
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483 | }, 30000);
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484 |
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485 | wss.on('close', function close() {
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486 | clearInterval(interval);
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487 | });
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488 | ```
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489 |
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490 | Pong messages are automatically sent in response to ping messages as required by
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491 | the spec.
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492 |
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493 | Just like the server example above, your clients might as well lose connection
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494 | without knowing it. You might want to add a ping listener on your clients to
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495 | prevent that. A simple implementation would be:
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496 |
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497 | ```js
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498 | import WebSocket from 'ws';
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499 |
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500 | function heartbeat() {
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501 | clearTimeout(this.pingTimeout);
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502 |
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503 | // Use `WebSocket#terminate()`, which immediately destroys the connection,
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504 | // instead of `WebSocket#close()`, which waits for the close timer.
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505 | // Delay should be equal to the interval at which your server
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506 | // sends out pings plus a conservative assumption of the latency.
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507 | this.pingTimeout = setTimeout(() => {
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508 | this.terminate();
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509 | }, 30000 + 1000);
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510 | }
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511 |
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512 | const client = new WebSocket('wss://websocket-echo.com/');
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513 |
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514 | client.on('error', console.error);
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515 | client.on('open', heartbeat);
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516 | client.on('ping', heartbeat);
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517 | client.on('close', function clear() {
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518 | clearTimeout(this.pingTimeout);
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519 | });
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520 | ```
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521 |
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522 | ### How to connect via a proxy?
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523 |
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524 | Use a custom `http.Agent` implementation like [https-proxy-agent][] or
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525 | [socks-proxy-agent][].
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526 |
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527 | ## Changelog
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528 |
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529 | We're using the GitHub [releases][changelog] for changelog entries.
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530 |
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531 | ## License
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532 |
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533 | [MIT](LICENSE)
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534 |
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535 | [`buffer.isutf8()`]: https://nodejs.org/api/buffer.html#bufferisutf8input
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536 | [bufferutil]: https://github.com/websockets/bufferutil
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537 | [changelog]: https://github.com/websockets/ws/releases
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538 | [client-report]: http://websockets.github.io/ws/autobahn/clients/
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539 | [https-proxy-agent]: https://github.com/TooTallNate/node-https-proxy-agent
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540 | [node-zlib-bug]: https://github.com/nodejs/node/issues/8871
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541 | [node-zlib-deflaterawdocs]:
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542 | https://nodejs.org/api/zlib.html#zlib_zlib_createdeflateraw_options
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543 | [permessage-deflate]: https://tools.ietf.org/html/rfc7692
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544 | [server-report]: http://websockets.github.io/ws/autobahn/servers/
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545 | [session-parse-example]: ./examples/express-session-parse
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546 | [socks-proxy-agent]: https://github.com/TooTallNate/node-socks-proxy-agent
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547 | [utf-8-validate]: https://github.com/websockets/utf-8-validate
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548 | [ws-server-options]: ./doc/ws.md#new-websocketserveroptions-callback
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