Node.js — WebSockets

What are WebSockets?

WebSockets provide full-duplex communication over a single TCP connection.

Basic WebSocket Server

const WebSocket = require('ws');
const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', (ws) => {
    console.log('Client connected');
    
    ws.on('message', (data) => {
        console.log('Received:', data);
        ws.send(`Echo: ${data}`);
    });
    
    ws.on('close', () => {
        console.log('Client disconnected');
    });
});

WebSocket Client

const ws = new WebSocket('ws://localhost:8080');

ws.on('open', () => {
    ws.send('Hello Server!');
});

ws.on('message', (data) => {
    console.log('Received:', data);
});

Broadcasting

wss.on('connection', (ws) => {
    ws.on('message', (data) => {
        // Broadcast to all clients
        wss.clients.forEach(client => {
            if (client.readyState === WebSocket.OPEN) {
                client.send(data);
            }
        });
    });
});

With Express

const express = require('express');
const http = require('http');
const WebSocket = require('ws');

const app = express();
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });

wss.on('connection', (ws) => {
    // Handle connection
});

server.listen(3000);

Mini Practice

1. Create a WebSocket server
2. Send and receive messages
3. Broadcast to all clients
4. Integrate with Express

Up Next

Continue with Database — connecting to databases.