How to track browser close

[Blikkies Marais]

Hi, does anyone know how to track when a browser closes. I want to perform a logoff function when the user closes the browser window by clicking X. In the logoff function I want to submit a form to invalidate the users session.
I have tried to use onUnload, but this occures everytime the url changes. I need to track only the close browser window.

[Eric Pascarello]

GOOD LUCK
There is no way to really track the browser close.
Methods used are (IE only onbeforeunload)
Replace all links on a page with a javascript code that detects user is going to not be leaving....Mess
You have problems with back button and refresh
There is no way to do it, if you are logging out from the server, you have better luck timing it out.
If it is logged in by cookies, use a session cookie.
Eric

[maneesh subherwal]

As Eric suggested, there is no real way to track this. However, I have figured a way out that currently works with my application. I have a hidden window that I use only for this purpose. When the user closes the browser window, that is the only way that this hidden window can be closed. When the unload method is called, i check a flag to see if the user has not exited cleanly already. If the user has not exit cleanly, the session is invalidated on the server using a modal window dialog.
hope this helps...
Maneesh