Event Emitter in Node.js
From the Node.js Core Modules cheat sheet · Streams & Events · verified Jul 2026
Event Emitter
Create and handle custom events for async communication
javascript
const EventEmitter = require('events');
class MyEmitter extends EventEmitter {}
const emitter = new MyEmitter();
// Listen for event
emitter.on('event', (data) => {
console.log('Event:', data);
});
// Emit event
emitter.emit('event', 'data');
// Once listener
emitter.once('close', () => {});🟢 Essential - Core of Node.js event-driven architecture
💡 Many Node.js objects extend EventEmitter
📌 removeListener() to prevent memory leaks
⚠️ Default max 10 listeners (setMaxListeners to change)
⚡ once() for one-time event handlers
🔗 Related: events.EventEmitter is the base class
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