Ajax loading Bar

Hello I am in need of a AJAX loading Bar. Basically a person will load a page in which an ad is show. The header of the page will contain my site logo and the timing bar. My project us built using codeigniter framework, so this MUST be able to be simply dropped in and can work, The Timer should be settable but 10seconds is fine. After 10 Seconds it will call back to a function that is written in my codeigniter controller, in which will then display a message, based on the results of the functions process. Also, if person leaves the page with the timer, the timer should stop working. I need this asap. Thanks