使用node、Socket.io 搭建简易聊天室

npm install socket-io -S
npm install express@4 -S

io.on('connection', socket => {

    console.log('a user connected!');

    //disconnect
    socket.on('disconnect', () => {
        console.log('a user disconnected!');
    })
}

io.sockets.emit(自定义参数，data)；

io.emit(自定义参数, data);

socket.emit(自定义参数，data)

socket.on(自定义参数，callback）

socket.on('disconnect',callback);

socket.broadcast.to(socketId ).emit('msg', msg)

io.to(roomId).emit('event name', {
    // some data
})

// join room
socket.join(roomId);

// leave room
socket.leave(roomId);

const express = require('express');
const app = express();
const http = require('http');
const server = http.createServer(app);
// Express 初始化app可以提供给HTTP服务器的函数处理程序
const { Server } = require("socket.io");
const io = new Server(server);
// socket.io自动为我们服务客户端传递server（HTTP 服务器）对象来初始化 的新实例。然后我监听connection传入套接字的事件并将其记录到控制台

app.get('/', (req, res) => {
	res.sendFile(__dirname + '/index.html');
});

let roomInfo = {};
let users = [];
io.sockets.on('connection', socket => {
	socket.on('disconnect', () => {
		console.log(`客户端断开链接`) 
	})
	socket.on('login', user => {
		if (-1 != users.indexOf(user)) {
			return false;
		}
		users.push(user)
		io.sockets.emit('login', user)
		io.sockets.emit('updateUserList', users)
	})
	socket.on('chat', data => {
		console.log(data, 'data')
		io.sockets.emit('chat', data)
	})
	socket.on('creatGroup', data => {
		if (!(data.roomId in roomInfo)) {
			roomInfo[data.roomId] = data;
		}
		io.sockets.emit('creatGroup', data.roomId)
	})
})
server.listen(3000, () => {
	console.log('listening on *:3000');
});

	<script src="/socket.io/socket.io.js"></script>
	<script>
	socket = io.connect();
		//登录
		loginDom.addEventListener('click', () => {
			let user = userDom.value.trim();
			if (!user) {
				alert('用户名为空')
				return
			}
			socket.emit('login', user, 1)
		})
		// 创建群组
		creatGroupDom.addEventListener('click', () => {
			let user = userDom.value.trim();
			let group = { user, roomId: `room_id_${(Date.now())}` }
			socket.emit('creatGroup', group)
		})
		// 监听创建群组
		socket.on('creatGroup', data => {
			creatGroupDom.innerHTML = `<dt>群组列表</dt>`
		})
		//服务器连接提示
		socket.on('connect', () => {
			addMsg(roomNoticeDom, `服务器连接成功`)
		})
		//登录
		socket.on('login', (user) => {
			addMsg(roomNoticeDom, `${user}进入房间`)
			document.getElementById('user').disabled = true;
		})
		//更新用户列表
		socket.on('updateUserList', users => {
			userListDom.innerHTML = `<dt>用户列表</dt>`
			// userListDom.removeChild(ddDom)
			for (let user of users) {
				let dd = document.createElement('dd')
				dd.innerText = user;
				userListDom.appendChild(dd)
			}
		})
		//监听消息
		socket.on('chat', (data) => {
			console.log('接收到消息')
			var item = document.createElement('li');
			item.style.background = '#ff0'
			item.textContent = `${data.user}说：${data.message}`;
			messages.appendChild(item);
			window.scrollTo(0, document.body.scrollHeight + 30);
		})
		//发送消息
		form.addEventListener('submit', (e) => {
			e.preventDefault();
			if (message.value) {
				console.log(message, user, '发送信息成功')
				socket.emit('chat', { message: message.value, user: userDom.value.trim() })
			}
			message.value = '';
		})
	</script>