JS适配问题。

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

window.cancelAnimationFrame =(function(){
    return window.cancelAnimationFrame ||
        window.cancelRequestAnimationFrame ||
        window.webkitCancelAnimationFrame || 
        window.webkitCancelRequestAnimationFrame ||
        window.mozCancelAnimationFrame || 
        window.mozCancelRequestAnimationFrame ||
        window.msCancelAnimationFrame || 
        window.msCancelRequestAnimationFrame ||
        window.oCancelAnimationFrame || 
        window.oCancelRequestAnimationFrame ||
        window.clearTimeout;
})();