How to control browser confirmation dialog on leaving page?

Question

I know there are a lot of questions regarding this but nothing is answering me right. I want to show a confirmation dialog when user leaves the page. If the user press Cance

Answer 1

Here's what I've done, modify to fit your needs:

// This default onbeforeunload event
window.onbeforeunload = function(){
    return "Do you want to leave?"
}

// A jQuery event (I think), which is triggered after "onbeforeunload"
$(window).unload(function(){
    //I will call my method
});

Note: it's tested to work in Google Chrome, IE8 and IE10.

Answer 2

 window.onbeforeunload = function() {
       if (data_needs_saving()) {
           return "Do you really want to leave our brilliant application?";
       } else {
          return;
       }
    };