tiny-emitter

Lightweight EventEmitter implementation with TypeScript support.

Install

npm install tiny-emitter

Usage

JavaScript / TypeScript

const { EventEmitter } = require('tiny-emitter');
// or ESM
import { EventEmitter } from 'tiny-emitter';

const emitter = new EventEmitter();

emitter.on('data', (msg) => {
  console.log('received:', msg);
});

emitter.emit('data', 'hello');

API

on(eventName, listener) / addListener(eventName, listener)

Register a listener for an event.

emitter.on('message', (data) => {
  console.log(data);
});

once(eventName, listener)

Register a one-time listener.

emitter.once('init', () => {
  console.log('initialized');
});

off(eventName, listener) / removeListener(eventName, listener)

Remove a listener.

const handler = (msg) => console.log(msg);
emitter.on('msg', handler);
emitter.off('msg', handler);

emit(eventName, ...args)

Emit an event. Returns true if listeners were called.

emitter.emit('update', { id: 1, name: 'test' });

removeAllListeners(eventName?)

Remove all listeners, or those for the specified event.

emitter.removeAllListeners('update');
emitter.removeAllListeners(); // remove all

listenerCount(eventName)

Get the number of listeners for an event.

console.log(emitter.listenerCount('update'));

listeners(eventName)

Get all listeners for an event.

console.log(emitter.listeners('update'));

eventNames()

Get all registered event names.

console.log(emitter.eventNames());

setMaxListeners(n)

Set max listeners (default: 10).

emitter.setMaxListeners(20);

getMaxListeners()

Get max listeners value.

console.log(emitter.getMaxListeners());

TypeScript

Full type definitions are included.

import { EventEmitter } from 'tiny-emitter';

interface UserEvent {
  id: number;
  name: string;
}

const emitter = new EventEmitter<UserEvent>();

emitter.on('user:login', ({ id, name }) => {
  console.log(`User ${name} (${id}) logged in`);
});

emitter.emit('user:login', { id: 1, name: 'John' });

Build

npm run build

License

MIT