JavaScript + onbeforeunload

Question

Hello, I have a query regarding my application. Whenever user closes browser window accidentally I'd want to do some clean up operations before that. I have used onunload event but problem is this event is sometimes is firing and sometimes doesn't. What should I do, is there better way to handle such type of problem.

Answer 1

From my experience onunload works differently in different browsers. Why dont you use another event handler called onbeforeunload instead. It should work. Onbeforeunload will execute first before the window closes, so that should solve your problem.

Answer 2

Try:

window.unbeforeunload = function() { ...your code... }

Answer 3

window.onbeforeunload = function() {
    return 'You have unsaved changes!';
}

See the MSDN article on onbeforeunload

Also there is a similar question in SO