Some times we need to detect the Browser Close to perform some operation before quiting from application. Here is a simple way.

Call this Method From Body Unload

function CheckBrowser()
{
// Check Browser Close [X] , Alt+F4 , File -> Close
if(window.event.clientX < 0 && window.event.clientY <0)
{
window.open("Operation.aspx",
"Operation",'left=12000,top=1200,width=10,height=1');
}
}

Read more: http://feeds.dzone.com/~r/dzone/snippets/~3/l-9lvpN-9TI/14263