实现websocket主要是两点，一个是协议的升级，再者就是数据包的解析与封装。

目前比较火的websocket框架有socket.io 和 ws

socket.io http://socket.io：43.5k star

实际上不是一个 WebSocket 库，而是一个实时 pub/sub 框架。简单地说，Socket.io 是包含 WebSocket 功能的一个框架，如果要使用该库作为 server 端的服务，则 client 也必须使用该库，因为它不是标准的 WebSocket 协议，而是基于 WebSocket 再包装的消息通信协议。

websockets/ws：9k star

强大易用的 websocket 服务端、客户端实现，还有提供很多强大的特性，最后选择 WS。

客户端代码：

<input type="text" name="msg">
<button type="button" onclick="send()">发送</button>
<script>
var socket = new WebSocket("ws://127.0.0.1:8080");
var stringData = "Hello 世界！";

socket.onopen = function(){
    console.log("open");
    socket.send(stringData);
}

socket.onerror = function(err){
    console.log("error: ", err);
}

socket.onclose = function(){
    console.log('close');
}

socket.onmessage = function(event){
    var data = event.data;
    console.log("收到服务器发来数据：", data);
    socket.send("收到服务器发来数据：" + data);
}

function send(){
    var msg = document.querySelector("input[name='msg']").value;
    socket.send(msg);
}
</script>

服务器端：

var WebSocket = require('ws');
// var { WebSocketServer } = require('ws');
var WebSocketServer = WebSocket.WebSocketServer;


const wss = new WebSocketServer({
  port: 8080,
  perMessageDeflate: {
    zlibDeflateOptions: {
      // See zlib defaults.
      chunkSize: 1024,
      memLevel: 7,
      level: 3
    },
    zlibInflateOptions: {
      chunkSize: 10 * 1024
    },
    // Other options settable:
    clientNoContextTakeover: true, // Defaults to negotiated value.
    serverNoContextTakeover: true, // Defaults to negotiated value.
    serverMaxWindowBits: 10, // Defaults to negotiated value.
    // Below options specified as default values.
    concurrencyLimit: 10, // Limits zlib concurrency for perf.
    threshold: 1024 // Size (in bytes) below which messages
    // should not be compressed if context takeover is disabled.
  }
});



wss.on('connection', function connection(ws) {
  console.log("websocket 链接中。。。");
  ws.on('open', function open() {
    console.log("websocket 创建成功。。。");
    ws.send('something');
  });


  ws.on('message', function message(data) {
    console.log('received: %s', data);
  });


  setInterval(function () {
    ws.send('你好，客户端！当前服务器时间是：' + Date());
  }, 1000);
});


wss.on('error', function (event) {
  console.log("错误信息：", event);
});

参考：

https://www.zhihu.com/question/37647173/answer/1403359896

https://www.ruanyifeng.com/blog/2017/05/websocket.html

socket 网络协议 RFC6455

修改时间 2022-05-31