Simplified events emitter (JS)

events_emitter_mixin.js

/**
 * Simple event dispatcher
 *
 * Example
 *
 * var MyConstructor = function () {
 *    var self = this
 *    var count = 0
 *    setInterval(function () {
 *      self.emit('tick', {count: count})
 *      count++
 *    }, 2000)
 * }
 * MyConstructor.prototype = new Events()
 *
 * var instance = new MyConstructor()
 * instance.on('tick', function (data) {
 *   console.log('Tock!', data)
 * })
 */
var Events = (function () {

  var Events = function () {
    this._handlers = {}
  }

  Events.prototype = {
    on: function (eventName, handlerFunc) {
      this._handlers[eventName] = this._handlers[eventName] || []
      this._handlers[eventName].push(handlerFunc)
      return this
    },
    emit: function (eventName, data) {
      if(!this._handlers[eventName]) return this
      this._handlers[eventName].forEach(function (handler) {
        handler(data)
      })
      return this
    }
  }

  return Events
})();