JQTouch glitch on the iPad

Question

I have a simple JavaScript function which replaces an image's source.

document.getElementById("star1_"+i).src ="full_star.png";

i being an id attached to the name to differentiate different stars.

It works fine in Safari, but once I add the site to home screen, this action stops working and the image source does not get replaced. Is there any reason this would be acting differently when launched from the home screen than in the normal Safari browser?