Please, I would really appreciate if you pros could help me on this. Sorry if it isn't posted on the right forum, but I guess my solution involves some issues for AJAX.

I want a client-side solution for a web page filter. It would act like a java filter, but not on the server-side. I need this filter so a user can call any web page through it and the filter would make adjustments on the final page presentation. On this initial state, I was using frames and the onLoad event for the main frame (presenting the web page to be filtered). Every time the event is triggered, it's because a new web page is presented on the main frame so I call this filter function to make the adjustments. The main problem is that, first, the page is loaded and only then I can make the adjustments. This is not good considering user interaction issues, so I was trying to use AJAX. I wondered to use the onUnload event to know where the user is navigating to and call it through AJAX, using XMLHttpRequest to get the page, format it, and only then presenting it as the final state of art. Anyway, I was told that "probably" there isn't a way to know, at the onUnload event, where the user is navigating to.

Do you guys have a better idea to solve this? Any suggestion is valuable. Thanks for your attention!