how to capture closing of a browser tab

Question

We would like to throw a specific message before a user closes the browser. Is there a mechanism which will work across all major browsers (like IE, firefox, chrome, opera)

Answer 1

Check onbeforeunload:

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

  if (has_message_to_throw) {

    // For IE and Firefox
    if (e) {
      e.returnValue = 'Specific message';
    }

    // For Safari
    return 'Specific message';

  }


};