Request Animation Frame Fallback

anim.js

 window.requestAnimFrame = (function(){
      return  window.requestAnimationFrame       || 
              window.webkitRequestAnimationFrame || 
              window.mozRequestAnimationFrame    || 
              window.oRequestAnimationFrame      || 
              window.msRequestAnimationFrame     || 
              function(callback){
                window.setTimeout(callback, 1000 / 60);
              };
 })();