loading_transition_mixin.coffee

Application.LoadingTransitionMixin = Ember.Mixin.create
  afterModel: (model, transition) ->
    previousRoute = @get('router').previousRoute
    
    if previousRoute
      @get('router').previousRoute.cleanUp()

  cleanUp: ->
    deferredPromise = new Ember.Deferred()
    @controller.set('cleanUpPromise', deferredPromise)
    deferredPromise

  actions:
    willTransition: (transition) ->
      @get('router').previousRoute = this

route_fade_view.coffee

Application.RouteFadeView = Ember.View.extend
  cleanUp: (->
    cleanUpPromise = @get('controller.cleanUpPromise')
    if cleanUpPromise
      @fade("0", =>
        cleanUpPromise.resolve()
      )
  ).observes('controller.cleanUpPromise')
  
  fade: (opacity, callback) ->
    currentOpacity = @$().css('opacity')
    return callback() if currentOpacity == opacity
    @$().css('opacity', opacity)
    @$().on('transitionend webkitTransitionEnd oTransitionEnd otransitionend MSTransitionEnd', =>
      @$().off('transitionend webkitTransitionEnd oTransitionEnd otransitionend MSTransitionEnd')
      Ember.run ->
        callback()
    )