WebSocket实时通信的实现（如聊天室）

// 客户端代码
const socket = new WebSocket('ws://localhost:8080');

socket.onopen = function(event) {
    console.log('WebSocket connection established');
    socket.send('Hello, server!');
};

socket.onmessage = function(event) {
    console.log('Message from server:', event.data);
};

socket.onclose = function(event) {
    console.log('WebSocket connection closed');
};

socket.onerror = function(error) {
    console.log('WebSocket error:', error);
};

// 服务器端代码（使用Node.js和ws库）
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', function connection(ws) {
    ws.on('message', function incoming(message) {
        console.log('received:', message);
        ws.send(`Hello, you sent: ${message}`);
    });

    ws.send('Welcome to the chat room!');
});

// 服务器端代码（实现聊天室功能）
const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

const clients = new Map();

wss.on('connection', function connection(ws) {
    const id = uuidv4();
    clients.set(id, ws);

    ws.on('message', function incoming(message) {
        const data = JSON.parse(message);
        switch (data.type) {
            case 'message':
                broadcastMessage(data.message, id);
                break;
            case 'private':
                sendPrivateMessage(data.to, data.message, id);
                break;
            case 'join':
                broadcastJoin(id, data.username);
                break;
            case 'leave':
                broadcastLeave(id);
                clients.delete(id);
                break;
        }
    });

    ws.on('close', function() {
        broadcastLeave(id);
        clients.delete(id);
    });
});

function broadcastMessage(message, senderId) {
    const sender = clients.get(senderId);
    const senderUsername = sender.username || 'Anonymous';

    clients.forEach((client, id) => {
        if (client.readyState === WebSocket.OPEN) {
            client.send(JSON.stringify({
                type: 'message',
                message: message,
                sender: senderUsername,
                senderId: senderId
            }));
        }
    });
}

function sendPrivateMessage(toId, message, senderId) {
    const toClient = clients.get(toId);
    const sender = clients.get(senderId);
    const senderUsername = sender.username || 'Anonymous';

    if (toClient && toClient.readyState === WebSocket.OPEN) {
        toClient.send(JSON.stringify({
            type: 'private',
            message: message,
            sender: senderUsername,
            senderId: senderId
        }));
    }
}

function broadcastJoin(id, username) {
    const client = clients.get(id);
    client.username = username;

    clients.forEach((client, clientId) => {
        if (client.readyState === WebSocket.OPEN) {
            client.send(JSON.stringify({
                type: 'join',
                username: username,
                id: id
            }));
        }
    });
}

function broadcastLeave(id) {
    clients.forEach((client, clientId) => {
        if (client.readyState === WebSocket.OPEN) {
            client.send(JSON.stringify({
                type: 'leave',
                id: id
            }));
        }
    });
}

function uuidv4() {
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
        var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16);
    });
}