EE (Event Emitter)

Tiny, typed event emitter utility for Node.js and browsers. No dependencies.

Need a single event and type, only? Check out Signal instead

Installation

npm install @soncodi/ee --save

Usage (TypeScript)

import { EE } from '@soncodi/ee';

// map event names to their callback param types
interface Events {
  a: number;
  b: string;
  c: undefined;
}

const ee = new EE<Events>();

const cb = (num: number) => console.log('A', num);

ee.on('a', cb);
ee.on('b', str => console.log('B', str));
ee.once('c', () => console.log('C'));

ee.emit('a', 123);
ee.emit('b', 'hello');
ee.emit('c');

ee.off('a', cb);

ee.event('b', 123); // error
ee.event('d', 123); // error

Methods

`on(event, fn)`

Attaches an event handler to be called whenever the event fires.

`once(event, fn)`

Attaches a one-time handler which is unbound after it fires the first time.

`off(event, fn?)`

Detaches one instance of a given handler from the event emitter. If no handler is provided, detaches all handlers.

`emit(event, arg)`

Fires the event synchronously, triggering any attached handlers with the given arg.

`event(event, arg)`

Fires the event asynchronously, triggering any attached handlers with the given arg. Useful when attaching handlers later in the same event loop turn.