The easiest way is to use two GIFs, one is a still image and the other contains multiple frames.

On mouse over, the still GIF is replaced with the animating one.

Edit:

Here's the full code: http://jsfiddle.net/khrismuc/epcqhp5b/

StackOverflow would be best place to ask this.

I am making a website and i want the effect that is done on this website below as soon as the mouse cursor stays on "2013" .

http://recap.bigcartel.com/

I want the code as soon as possible!