window.requestAnimationFrame

(function() {

    var lastTime = 0;
    var vendors = ['ms', 'moz', 'webkit', 'o'];

    for(var x = 0; x < vendors.length && !window.requestAnimationFrame; x++) {

        window.requestAnimationFrame = window[vendors[x] + 'requestAnimationFrame'];

        window.cancelRequestAnimationFrame = window[vendors[x] + 'CanelAnimationFrame'] ||
            window[vendors[x] + 'CancelRequestAnimationFrame'];
    }

    if(!window.requestAnimationFrame) {
        window.requestAnimationFrame = function(callback, element) {
            var currentTime = new Date().getTime();
            var timeToCall = Math.max(0, 16 - (currentTime - lastTime));
            var id = window.setTimeout(function() {
                callback.call(currentTime + timeToCall);
            }, timeToCall);

            lastTime = currentTime + timeToCall;
            return id;
        }
    }

    if(!window.cancelRequestAnimationFrame) {
        window.cancelRequestAnimationFrame = function(id) {
            clearTimeout(id);
        }
    }
}());