window.onbeforeunload runs only when closing window not on refresh

Question

I have this function

 window.onbeforeunload = function () {        
          return "Are you sure?";        
    };

and I have a button that when the user presses it the window refreshes to update screen values and do some database calls. I added window.onbeforeunload=null; in the beginning of the function to disable onbeforeunload but it kept being called.

Is there a way to either disable the onbeforeunload function in my button onclick function or make the window.onbeforeunload get called only on close window not on refresh?

Answer 1

Following code should work (should be kept inside head tag between script tags)

window.onload=function(){

    window.onbeforeunload = function(){        
        return "Are you sure?";        
    }

    document.getElementById('refresh').onclick=function(){
        window.onbeforeunload = null;
        window.location.reload(); // replace with your code
    }
}​

WORKING DEMO.