javascript - Intercept selection in window.onbeforeunload dialog -

in web application if user leaves current page without having saved changes in form pop window opened alert him that.

for pop use scripts code injected codebehind (c#):

var confirm = true; window.onbeforeunload = confirmclose;   function confirmclose()  {    if (!confirm) return;     if(/*check change condition true*/)       { return " + warn_message + "; } }  

i need intercept whether user click on cancel or ok button.

i tried like:

var button_pressed = window.onbeforeunload = confirmclose; 

but returns true.

how can button pressed? thanks

not possible. there no event associated buttons. might able see if user came setting value or perhaps cookie in page in onbeforeunload , test if there after time has passed

but see duplicate way know if user clicked cancel on javascript onbeforeunload dialog?