When I am closing my browser I want a confirmation message.
 
 
I am using
 
 window.onbeforeunload = confirmExit;
        function confirmExit() {
            return "You will Lost this test.  Are you sure you want to exit this  page?";
        }
 
But this  function is also working on page postback on my page.
I want this message on window cclose only
What should I have to do.????