I've currently got a project that does not make use of any framework and now it is becoming larger I'm getting the feeling now might be a good time to move to a framework to simplify things and bring some order back.

However, I'm struggling to find an appropriate framework. The project is very AJAX/JS heavy as it is more of a web application than some kind of standard website. In fact there are a total of 2 different pages (index.php and admin.php) that are accessed directly, the rest is called by AJAX.

The javascript is written using jQuery but most of the data is passed using JSON, with the exception of some additional HTML that is needed. However, I don't want to be forced into using a different JS framework by the PHP framework.

Has anyone got any recommendations to what kind of framework would be best suited to this AJAX heavy environment?