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>
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