koa与socket.io简单流程分析：1. 服务端触发初始化io.on(‘connection’, socket => {});2. 客户端发送say会话socket.emit(‘say’, ‘我是客户端’); 3. 服务端监听say会话socket.on(‘say’,data => {}); 4. 服务端发送message会话socket.emit(‘message’, {hello: ‘你是谁’});5. 客户端接收message消息socket.on(‘message’, (data) => {});服务端：const koa = require(‘koa’);const app = new koa();const server = require(‘http’).Server(app.callback())const io = require(‘socket.io’)(server);const port = 8081;server.listen(process.env.PORT || port, () => { console.log(app run at : http://127.0.0.1:${port});})io.on(‘connection’, socket => { console.log(‘socket初始化完成’); socket.on(‘say’, data => { console.log(data, ‘接收到的信息’) socket.emit(‘message’, {hello: ‘你是谁’}) })})客户端<!DOCTYPE html><html lang=“en”><head> <meta charset=“UTF-8”> <title>Document</title> <style> input { background-color: #fff; background-image: none; border-radius: 4px; border: 1px solid #bfcbd9; box-sizing: border-box; color: #1f2d3d; font-size: inherit; height: 40px; line-height: 1; outline: 0; padding: 3px 10px; } .el-button–primary { color: #fff; background-color: #20a0ff; border-color: #20a0ff; } .el-button { display: inline-block; line-height: 1; white-space: nowrap; cursor: pointer; background: #00aac5; border: 1px solid #c4c4c4; color: #fff; margin: 0; padding: 10px 15px; border-radius: 4px; outline: 0; text-align: center; } </style></head><body> <div> <div id=“content”> </div> </div> <div> <input type=“text” id=“input”> <button class=“el-button el-button–primary el-button–large” type=“button” onclick=“say()"><span>发送消息</span></button> </div> <script src=”./socket.io.js"></script> <script> // 建立连接 var socket = io.connect(‘http://localhost:8081’); // 监听 message 会话 socket.on(‘message’, function (data) { let html = document.createElement(‘p’) html.innerHTML = 系统消息：<span>${data.hello}</span> document.getElementById(‘content’).appendChild(html) console.log(data); }); // 按钮点击事件 function say() { let t = document.getElementById(‘input’).value if (!t) return let html = document.createElement(‘p’) html.innerHTML = 你细声说：<span>${t}</span> document.getElementById(‘content’).appendChild(html) socket.emit(‘say’, { my: t}); } // 监听 news 会话 socket.on(’news’, function (data) { console.log(data); let html = document.createElement(‘p’) html.innerHTML = 小皮咖说：<span>我知道了，你说“${data.hello}”</span> document.getElementById(‘content’).appendChild(html) }); // 监听吃饭会话 socket.on(’eating’, function (data) { console.log(data); let html = document.createElement(‘p’) html.innerHTML = 小皮咖说：${data.hello} document.getElementById(‘content’).appendChild(html) }); </script></body></html>