Socket.IO

Overview

Socket.IO is the most popular real-time communication library for Node.js. It provides bidirectional event-based communication between client and server, with automatic fallback from WebSocket to HTTP long-polling, reconnection handling, room-based broadcasting, and namespace isolation. This skill covers server setup, client integration, rooms, authentication middleware, scaling with Redis, and common patterns like chat, notifications, and presence.

Instructions

Step 1: Installation

# Server
npm install socket.io

# Client
npm install socket.io-client

# Redis adapter (for scaling across multiple servers)
npm install @socket.io/redis-adapter redis