🔌 WebSockets Learning Notes

📂 Topics Covered

File Description Status
WebSocket WebSocket Fundamentals ✅ Done

🎯 Quick Reference

HTTP vs WebSocket

| Feature | HTTP | WebSocket | |———|——|———–| | Connection | Request-Response | Persistent | | Direction | Client-initiated | Bidirectional | | Overhead | Headers each time | Low after handshake | | Use Case | REST APIs | Real-time apps |

WebSocket Lifecycle

1. Client: HTTP Upgrade Request
2. Server: 101 Switching Protocols
3. Both: Full-duplex communication
4. Either: Close connection

Client Example (JavaScript)

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

ws.onopen = () => {
  console.log('Connected');
  ws.send('Hello Server!');
};

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

ws.onclose = () => {
  console.log('Disconnected');
};

ws.onerror = (error) => {
  console.error('Error:', error);
};

Server Example (Node.js)

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

wss.on('connection', (ws) => {
  ws.on('message', (message) => {
    console.log('Received:', message);
    ws.send('Echo: ' + message);
  });
});

Use Cases

📚 Resources

Last Updated: March 2026