Confirmation on Leaving the Current Page in JavaScript

onbeforeunload-1.js

function goodbye(e) {
	if(!e) e = window.event;
	//e.cancelBubble is supported by IE - this will kill the bubbling process.
	e.cancelBubble = true;
	e.returnValue = 'You sure you want to leave?'; //This is displayed on the dialog

	//e.stopPropagation works in Firefox.
	if (e.stopPropagation) {
		e.stopPropagation();
		e.preventDefault();
	}
}
window.onbeforeunload=goodbye;

onbeforeunload-2.js

window.onbeforeunload = function (e) {
  var message = "Your confirmation message goes here.",
  e = e || window.event;
  // For IE and Firefox
  if (e) {
    e.returnValue = message;
  }

  // For Safari
  return message;
};

onbeforeunload-3.js

window.onbeforeunload=function(e){
  // only take action (iterate) if my SCHEDULED_REQUEST object contains data        
  for (var key in SCHEDULED_REQUEST){   
    postRequest(SCHEDULED_REQUEST); // post and empty SCHEDULED_REQUEST object
    for (var i=0;i<1000;i++){
      // do something unnoticable but time consuming like writing a lot to console
      console.log('buying some time to finish saving data'); 
    };
    break;
  };
}; // no return string --> user will leave as normal but data is send to server