How can I override the OnBeforeUnload dialog and replace it with my own?

Question

I need to warn users about unsaved changes before they leave a page (a pretty common problem).

window.onbeforeunload=handler

This works bu

Answer 1

You can detect which button (ok or cancel) pressed by user, because the onunload function called only when the user choise leaveing the page. Althoug in this funcion the possibilities is limited, because the DOM is being collapsed. You can run javascript, but the ajax POST doesn't do anything therefore you can't use this methode for automatic logout. But there is a solution for that. The window.open('logout.php') executed in the onunload funcion, so the user will logged out with a new window opening.

function onunload = (){
    window.open('logout.php');
}

This code called when user leave the page or close the active window and user logged out by 'logout.php'. The new window close immediately when logout php consist of code:

window.close();