An Event Emitter forked from Backbone.js
My framework of choice is backbone.js and it uses Backbone.Events to implement Event Emitters.
var mySimpleObject =name: "John"surname: "Doe"gender: "Male";// use underscore to extend mySimpleObject with Backbone.Events_extendmySimpleObject BackboneEvents;mySimpleObjecton'customEvent'// do something cool;mySimpleObjecttrigger'customEvent';
In the above example we simply extend a normal object with Backbone.Events to turn it into an Event Emitter.
Node.js also has a powerful EventEmitter object that can be used to add some awesomeness to objects.
var util = require'util';var EventEmitter = require'events'EventEmitter;// here is an ordinary object representing my Dogvar myDog =name: 'Spotty'likes: 'bones' 'biskuits'ate:thisatefood;// Add some magic to my ordinary objectutilinheritsmyDog EventEmitter;// Now my object can listen to and emit eventsmyDogon'hungry'myDogfeed'bone';myDogemit'hungry';
Using Event Emitters has many advantages; you can emit events when an object's state changes, objects can eavesdrop on other objects, reduces callback nesting, e.t.c.
An Event Emitter would have the same API as Object in ES5.
// an emptyvar emitter1 = EventEmittercreatenull;var mySimpleObject =name: "John"surname: "Doe"gender: "Male";var emitter2 = EventEmittercreatemySimpleObject;
Since native Event Emitters are just but a wishlist for now, I have forked Backbone Events and created a small library called Emitter. You can drop it into your project to start messing with Event Emitters.
Emitter uses the same API as Backbone.Events. The only different is that I have renamed the
trigger method to
emit. Below is an example of how to use Emitter.
"use strict";// in Node require the modulevar Emitter = require'emitter';// In the browser include the script in your html// <script src="dest/emitter.min.js"></script>var Dog = Emitterextendthisemit'buck';;var Person = Emitterextendthisemit'run';thisrunning = true;;var intruder = ;var myPet = ;myPeton'buck'console.log'My dog is bucking';;intruderon'run'console.log'The intruder is rinning away';;intruderlistenTomyPet 'buck' intruderrun;myPetbuck;
npm install emiter
npm run-script example1npm run-script example2
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