@sahnee/eventemitter

Yet another EventEmitter

Features

• Classic subscription based event emitter class
• Observer pattern
• Written in TypeScript
• Fully unit tested

EventEmitter

The EventEmitter is the main usage of this library. You can either use it as a standalone class instance of inherit your own classes form it.

It features all basic functions of an event emitter:

import EventEmitter from '@sahnee/eventemitter';

const ee = new EventEmitter();
ee.on('my-event', args => console.log('Event:', args));
ee.emit('my-event', 1);
ee.emit('my-event', 2);
// Prints:
// - Event: 1
// - Event: 2

All supported functions and properties are. Parameters marked with ? are optional:

• prefix - A prefix used for non symbol events to avoid e.g. prototype pollution. By default '~'.
• eventNames() - The names of all currently registered events.
• listeners(event) - Gets all listeners of the given event.
• listenerCount(event) - Gets amount of listeners for the given event.
• emit(event, ...args) - Emits the given event and invokes all handlers for it.
• addEventListener(event, fn, context?, once?, priority?) - Adds an event listener to the given event. Options are:
  • context - What this will refer to in your callback.
  • once - If this is true the event handler will once be invoked once.
  • priority - The priority of the event handler. See the numeric Priority enum for recommended base values.
• on(event, fn, context?, priority?) - Alias for addEventListener(event, fn, false, context, priority).
• once(event, fn, context?, priority?) - Alias for addEventListener(event, fn, true, context, priority).
• removeListener(event, fn?: ListenerFn, context?, once?, priority?) - Removes a event handler again.
• off(event, fn?: ListenerFn, context?, once?, priority?) - Alias for removeListener with the same parameters.
• removeAllListeners(event?) - Removes either all listeners of the entire emitter or just for the given event.

Observer

The observer pattern is currently not part of the stable public API. Usage is therefore discouraged.