session timeout

[eluser]Unknown[/eluser]
Hi all, im looking for a way to capture session expired from javascript. I can easily write a timer to periodically check if the session is still active, but I dont want my timer script to actually update the session timeout. I guess I could not autoload the session library, and instead manually load it on every page I use instead of the 'check' page, but thats such a hassle.

The goal is to redirect users to the login page if their session is expired instead of them only finding out after they try to do something.

Anyone have any tips?