Provides requestAnimationFrame in a cross browser way.

RequestAnimationFrame.js

/**
 * Provides requestAnimationFrame in a cross browser way.
 * @author paulirish / http://paulirish.com/
 */

if ( !window.requestAnimationFrame ) {

	window.requestAnimationFrame = ( function() {

		return window.webkitRequestAnimationFrame ||
		window.mozRequestAnimationFrame ||
		window.oRequestAnimationFrame ||
		window.msRequestAnimationFrame ||
		function( /* function FrameRequestCallback */ callback, /* DOMElement Element */ element ) {

			window.setTimeout( callback, 1000 / 60 );

		};

	} )();

}

setTimeout is many times inaccurate, and so is setInterval. More importantly, however, setTimeout(1000/60) doesn't take into account where we are wrt to the next vsync (it always assume we have the full frame time ahead of us), so it needs to align to the "independent" intervals of an imaginary vsync signal.

var rAF = function(callback) {
  var interval = 1000 / 60;
  var now = (window.performance && window.performance.now) ?
            window.performance.now() :
            Date.now();
  // setTimeout can return early, make sure to target the next frame.
  if (this.lastTarget && now < this.lastTarget)
    now = this.lastTarget + 0.01; // Floating point errors may result in just too early.
  var delay = interval - now % interval;
  this.lastTarget = now + delay;
  setTimeout(callback, delay);
};

My animation is magically smooth now! ;)

just leaving there CoffeeScript code snippet

###
# Provides requestAnimationFrame in a cross browser way.
# @author paulirish / http://paulirish.com/
###
unless window.requestAnimationFrame
    window.requestAnimationFrame = window.webkitRequestAnimationFrame or
        window.mozRequestAnimationFrame or
        window.oRequestAnimationFrame or
        window.msRequestAnimationFrame or
        (callback, element) -> window.setTimeout callback, 1000 / 60

hi, what is the diff to the following last post? http://codereview.stackexchange.com/questions/60216/gameloop-with-requestanimationframe (cc GameAlchemist answered Aug 19 '14 at 11:58)

I cant understand one thing, why do we need to use the delay as 1000/60 why not just the resulting figure that evaluates by dividing 1000 by 60 what if I just put any round figure, and does animationFrameRate help us slowing down the animation without the setTimeout function, and under what conditions should we use it this way setTimeout(callback, 1000 / 60); and not setTimeout(callback, 1000);

Hi @mrdoob, why do we need the /* DOMElement Element */ element in the function?

@buttflattery I know this is an old post, but I'm replying for any future people who see this. You use 1000 / 60 because it results to around 16.667 milliseconds. If you were to use this number, it would call the render function almost exactly 60 times per second, meaning 60 FPS. You could easily do 1000 / 80 to get 80 FPS if you really wanted, but 60 FPS is a common number for monitor refresh rates. If you were to use 1000 as the delay, then you would only get 1 frame per second.