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boyboi86/EventEmitter.js

Created October 24, 2016 09:41
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Building event emitter in ES6
Raw
EventEmitter.js
class EventEmitter {
constructor(){
this.events = {};
}
on(eventName, cb){
if(this.events[eventName]){
this.events[eventName].push(cb);
} else {
this.events[eventName] = [cb];
}
}
emit(eventName, ...rest){
if(this.events[eventName]){
this.events[eventName].forEach(cb => {
cb.apply(null, rest);
})
}
/* Test it */
const ee = new EventEmitter()
ee.on('test', () => {
console.log('EventEmitter works!!')
})
ee.emit('test');
}
}
@boyboi86
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ES5 version would be as follows:

function EventEmitter(){
  this.events = {};
}

EventEmitter.prototype.on = function(eventName, cb) {
 if(this.events[eventName]) {
  this.events[eventName].push(cb);
 } else {
  this.events[eventName] = [cb];
 }
}

EventEmitter.prototype.emit = function(eventName) {
  if(this.events[eventName]){
  this.events[eventName].forEach((cb) => {
    cb()
  })
  }
}

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