AS3 like EventDispatcher

EventDispatcher.coffee

class EventDispatcher
	constructor: () ->
		@_listeners = {}

	addEventListener: (type, listener) ->
		return unless typeof listener == 'function'
		@_listeners[type] ?= []
		for l in @_listeners[type]
			return if l == listener
		@_listeners[type].push(listener)

	removeEventListener: (type, listener) ->
		return unless hasEventListener(type)
		for l, i in @_listeners[type]
			@_listeners[type].splice(i, 1) if l == listener
		delete @_listeners[type] if @_listeners[type].length == 0

	removeAllEventListeners: (type = '') ->
		if type == '' then @_listeners = {} else delete @_listeners[type]

	hasEventListener: (type) ->
		return @_listeners[type]?

	dispatchEvent: (type, args = null) ->
		return unless hasEventListener(type)
		for l in @_listeners[type]
			l.apply(this, args)