How to implement WebSockets in JavaScript

Short answer

Use the browser's native WebSocket object to open a persistent connection to a server, then send and receive messages through event handlers like onopen, onmessage, and onclose.

Details

A minimal client implementation looks like this:

const socket = new WebSocket('wss://example.com/socket');
socket.onopen = () => socket.send('hello');
socket.onmessage = (event) => console.log('Received:', event.data);
socket.onclose = () => console.log('Disconnected');

Because WebSocket communication is asynchronous, modern code usually wraps it in promises or async/await patterns for cleaner flow control. Understanding JavaScript closures helps manage event callbacks without leaking scope. To keep the UI responsive, integrate socket data with rendering loops and measure the impact on Core Web Vitals if updates trigger large DOM changes.

Tips

• Implement heartbeat pings and automatic reconnection for production reliability.
• Use binary frames (ArrayBuffer or Blob) instead of JSON strings for large payloads.
• Secure connections with wss:// and validate all incoming messages on the server.