CSS animation doesn't restart when resetting class

Question

I am using CSS shader + animation. My shader class is defined as follows:

.shader{
-webkit-filter :custom(url(v.vs) mix(url(f.fs) multiply destination-over), 200 200);
-webkit-animation-name: test;
-webkit-animation-duration: 2s;
-webkit-animation-iteration-count: 1
}

I am trying to set/unset the styles(shader+animation) dynamically using jquery through $('#holder').addClass('shader'); and $('#holder').removeClass('shader');

However, the weird thing is when I reset the class (e.g., calling addClass after removeClass), only the shader gets reapplied but the animation doesn't (I have hooked the AnimationStart event to see when my animation starts). Anyone know why this is the case and how I can solve it?

Edit: I added a simplified version of JSfiddle snippet here. Essentially I'm re-applying the animation to a div twice but the actual animation only gets called the first time.

Answer 1

The problem is that, even though you remove and then re-apply the animated class, you do this in the course of a single, blocking function. When your function exits, it appears to the rendering engine that nothing has changed.

One solution (the one that you chose), is to clone the element and destroy the original. This is fine, but if you had any event bindings to the original element (i think) they they will be destroyed too.

Another approach is to remove the animated class from the element, and then wrap the code that re-applies the class inside of a setTimeout() call with a very small delay, e.g.

$('#holder').removeClass('shader');
setTimeout(
    function(){$('#holder').addClass('shader')}
    , 1);

I've tweaked your jsfiddle to use this approach: http://jsfiddle.net/HuFBN/7/

Answer 2

According to a 2011 article on css-tricks.com, triggering a reflow in between removing and adding the class will restart the animation. Example (verbose):

$('#holder').removeClass('shader');
$('#holder').offsetWidth = $('#holder').offsetWidth; // triggers reflow
$('#holder').addClass('shader'); // restarts animation