ev-emitter

What is ev-emitter?

The ev-emitter package is a simple event emitter library for JavaScript. It allows you to add event-driven architecture to your applications by providing methods to emit events and listen for them.

What are ev-emitter's main functionalities?

Add Event Listener

This feature allows you to add an event listener for a specific event. In the code sample, an event listener is added for the 'event' event, and when the event is emitted, the callback function `onEvent` is executed.

const EvEmitter = require('ev-emitter');
const emitter = new EvEmitter();

function onEvent() {
  console.log('Event triggered!');
}

emitter.on('event', onEvent);
emitter.emitEvent('event');

Remove Event Listener

This feature allows you to remove an event listener for a specific event. In the code sample, the event listener for the 'event' event is removed before the event is emitted, so the callback function `onEvent` is not executed.

const EvEmitter = require('ev-emitter');
const emitter = new EvEmitter();

function onEvent() {
  console.log('Event triggered!');
}

emitter.on('event', onEvent);
emitter.off('event', onEvent);
emitter.emitEvent('event');

Emit Event

This feature allows you to emit an event, triggering all the listeners that are registered for that event. In the code sample, the 'event' event is emitted, and the callback function `onEvent` is executed.

const EvEmitter = require('ev-emitter');
const emitter = new EvEmitter();

function onEvent() {
  console.log('Event triggered!');
}

emitter.on('event', onEvent);
emitter.emitEvent('event');

Other packages similar to ev-emitter

events

The 'events' package is the built-in Node.js event emitter module. It provides a similar event-driven architecture and is widely used in Node.js applications. Compared to ev-emitter, 'events' is more feature-rich and is part of the Node.js core modules.

eventemitter3

The 'eventemitter3' package is a high-performance event emitter for both Node.js and the browser. It offers a similar API to ev-emitter but is optimized for performance and has a smaller footprint. It is a good alternative if you need a lightweight and fast event emitter.

mitt

The 'mitt' package is a tiny functional event emitter. It provides a minimalistic API for event handling and is suitable for use in both Node.js and browser environments. Compared to ev-emitter, 'mitt' is even more lightweight and has a simpler API.

README

EvEmitter

Lil' event emitter — add a little pub/sub

EvEmitter adds publish/subscribe pattern to a browser class. It's a smaller version of Olical/EventEmitter. That EventEmitter is full featured, widely used, and great. This EvEmitter has just the base event functionality to power the event API in libraries like Isotope, Flickity, Masonry, and imagesLoaded.

API

// class inheritence
class MyClass extends EvEmitter {}

// mixin prototype
Object.assign( MyClass.prototype, EvEmitter.prototype );

// single instance
let emitter = new EvEmitter();

on

Add an event listener.

emitter.on( eventName, listener )

• eventName - String - name of the event
• listener - Function

off

Remove an event listener.

emitter.off( eventName, listener )

once

Add an event listener to be triggered only once.

emitter.once( eventName, listener )

emitEvent

Trigger an event.

emitter.emitEvent( eventName, args )

• eventName - String - name of the event
• args - Array - arguments passed to listeners

allOff

Removes all event listeners.

emitter.allOff()

Code example

// create event emitter
var emitter = new EvEmitter();

// listeners
function hey( a, b, c ) {
  console.log( 'Hey', a, b, c )
}

function ho( a, b, c ) {
  console.log( 'Ho', a, b, c )
}

function letsGo( a, b, c ) {
  console.log( 'Lets go', a, b, c )
}

// bind listeners
emitter.on( 'rock', hey )
emitter.on( 'rock', ho )
// trigger letsGo once
emitter.once( 'rock', letsGo )

// emit event
emitter.emitEvent( 'rock', [ 1, 2, 3 ] )
// => 'Hey', 1, 2, 3
// => 'Ho', 1, 2, 3
// => 'Lets go', 1, 2, 3

// unbind
emitter.off( 'rock', ho )

emitter.emitEvent( 'rock', [ 4, 5, 6 ] )
// => 'Hey' 4, 5, 6

Browser support

EvEmitter v2 uses ES6 features like for...of loops and class definition as such it supports Chrome 49+, Firefox 45+, Safari 9+, and Edge 13+.

For older browser support, use EvEmitter v1.

License

EvEmitter is released under the MIT License. Have at it.