It's really hard to tell, but one of the 9001 ads on the page may be clobbering the $
object.
jQuery provides the global jQuery
object (which is present on your page). You can do the following to "get" $
back:
jQuery(document).ready(function ($) {
// Your code here
});
If you think you're having jQuery problems, please use the debug (non-production) versions of the library.
Also, it's probably not best to be editing a live site like that ...