rAF.js

// requestAnimationFrame POLYFILL ////////////////////////////////////////////////////////////////////
// requestAnimationFrame and cancelAnimationFrame polyfill based on Erik Möller's one: https://gist.github.com/paulirish/1579671
// MDN Docs: https://developer.mozilla.org/es/docs/DOM/window.requestAnimationFrame
// @source https://gist.github.com/Danziger/fc83f1b2f16f70655a4a
// @license MIT license
 
(function(strict, calculations){
	"use strict";
	
	var vendors = ['webkit', 'moz', 'ms', 'o'];

	// Try to find the vendor's version:
	
	for(var i = 0, L= vendors.length; !window.requestAnimationFrame && i<L; ++i) {
		window.requestAnimationFrame = window[vendors[i]+'RequestAnimationFrame'];
	}
		
	window.cancelAnimationFrame = window.cancelAnimationFrame?window.cancelAnimationFrame:(window[vendors[i]+'CancelAnimationFrame'] || window[vendors[i]+'CancelRequestAnimationFrame']);
	
	// If there is no requestAnimationFrame yet or it is there, but there is no cancelAnimationFrame and we prefer to have both implemented with timers:
	
	if (!window.requestAnimationFrame || (!window.cancelAnimationFrame && strict)){
	
		var lastTime = 0;
	
		if(calculations){ // setTimeout version with calculations:
		
			window.requestAnimationFrame = function(callback, element) {
				var currTime = new Date().getTime();
				var timeToCall = Math.max(0, 16 - (currTime - lastTime));
				var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall);
				lastTime = currTime + timeToCall;
				return id;
			};
		}
		else{ // simplier setTimeout version without calculations (less overhead):
		
			window.requestAnimationFrame = function(callback, element){
				var id = window.setTimeout(function(){
					callback(+new Date);
				}, 1000 / 60);
				
				return id;
			};
		}
 
		window.cancelAnimationFrame = function(id) {
			clearTimeout(id);
		};
	}

})(false, false); // (strict, calculations)

/*
	strict = false
		We will have a requestAnimationFrame but cancelAnimationFrame is not guaranteed.
		
	strict = true
		We will always have a requestAnimationFrame and a cancelAnimationFrame, but they may be
		implemented using setTimeout even thought there's a specific vendor's version of
		requestAnimationFrame (but not of cancelAnimationFrame).
		
	calculations = false
		If setTimeout is used, it will have a constant time between calls (1000/60).
		
	calculations = true
		If setTimeout is used, it will do some calculations to determine the time between calls.
*/