beforeunload event on div?

beforeunload event on div?

I have to bind beforeunload event to div. If the div unload I want to prompt user with an alert you have "unsaved changes". 

when I attach beforeunload event on window element. 
  1. $(window).bind 'beforeunload', (event) ->
  2.       # on window unload

It works as expected but I want it to listen on unload of div.