how to identify onbeforeunload was caused by clicking close button

Question

How do I determine if onbeforeunload was caused by clicking the close button or a page refresh or generally what event caused onbeforeunload?

here is a snippet:

Answer 1

I searched for something similar but ended up empty handed. So I tried doing the opposit

We can identify all the events but browser events. Refer below (Untested) snippet.

var target = $( e.target );
if(!target.is("a, :button, :submit, :input, .btn, .bulkFormButton")){
//Your code for browser events)
}
   $("form").submit(function () {
             //Your code for browser events)
   });

This worked for me but there are still some events that are not handled. I am in search of those. If anyone have idea about them please share.