javascript to check when the browser window is close

Question

Does anyone know any way that I can use javascript to check when the browser window is close and pop-up a confirmation dailog to ask whether the user is confirm to exit the browser or change his mind to stay?

Answer 1

window.onbeforeunload = function (e) {
  var e = e || window.event;

  //IE & Firefox
  if (e) {
    e.returnValue = 'Are you sure?';
  }

  // For Safari
  return 'Are you sure?';
};

https://developer.mozilla.org/en/DOM/window.onbeforeunload