[Javascript] Title bar X button close event trigger

Javascript

/* 
window.opener.top.unblockUI();
The function unblockUI at the most top html.
*/
window.onbeforeunload = function(event)
{
  return  window.opener.top.unblockUI();
}

/* 
Q : When press F5 also trigger this function. 
A : Add window.opener.top.blockUI(); under function init()
*/

function init()
{
    window.opener.top.blockUI();
}

HTML

<button onClick="self.close();" type="button"><span>Close</span></button>

Reference:

Modal - Return value when Close (‘X’) button is clicked.

How to check whether (X) button in clicked in popup window

onbeforeunload event | beforeunload event

disable f5 and browser refresh using javascript

Close Event In Javascript For Firefox, IE and Chrome