Animation Detector. Watches for the end of and animation to execute a callback and on start you can add the proper classes to start the animation.

animation.js

var Animation = (function (){
  var animationEvent = (function whichAnimationEvent(){
    var t, el = document.createElement("fakeelement")
    ,animation = null
    ,animations = {
      "WebkitAnimation": "webkitAnimationEnd",
      "MozAnimation": "animationend",
      "OAnimation": "oAnimationEnd",
      "animation": "animationend"
    };
    for(t in animations) if(!animation && el.style[t] !== undefined) {
      animation = animations[t];
    }
    return animation;
  })();

  function Animation(elem){
    this.elem = elem;
    var self = this;
    this.elem.on(animationEvent, function (){
      self.isExecuting = false;
      return self.onAnimationEnd && self.onAnimationEnd();
    });
  }
  Object.defineProperties(Animation.prototype, {
    'start': {
      value: function (){
        if(this.onAnimationStart) this.onAnimationStart(); 
        this.isExecuting = true;
        return this;
      }
    }
    ,'before': {
      value: function (callback){
        this.onAnimationStart = callback;
        return this;
      }
    }
    ,'after': {
      value: function (callback){
        this.onAnimationEnd = callback;
        return this;
      }
    }
  });
  return Animation;
})();