A component that can be used by modules to give them simple emit/on event systems

EventManager.js

export default function EventManager() {
  const events = {};

  function emit(event) {
    if (typeof events[event] === 'undefined') return false;

    for (let i = 0, l = events[event].length; i < l; i++) {
      events[event][i].apply(this, Array.prototype.slice.call(arguments, 1));
    }
  }

  function on(event, callback) {
    if (typeof events[event] === 'undefined') events[event] = [];

    events[event].push(callback);

    return this;
  }

  return {
    emit: emit,
    on: on
  }
}

index.js

import EventManager from './EventManager.js';

var myMod = new SomeModule();
myMod.on('change', function(newValue) {
  console.log('myMod was changed to ' + newValue);
});

myMod.setValue('test'); // "myMod was changed to test"

SomeModule.js

import EventManager from './EventManager.js';

export default function SomeModule() {
  var events = new EventManager();
  var value;
  
  function setValue(val) {
    value = val;
    events.emit('change', val);
  }
  
  return Object.assign({}, events, {
    // Public module methods
  });
}