javascript to capture the browser or tab closed event

/*Refer  <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script> too*/

var validNavigation = false;

function endSession() {
  // Browser or broswer tab is closed
  // Do here ...
  alert("bye");
}

function wireUpEvents() {
  /*
  * For a list of events that triggers onbeforeunload on IE
  * check http://msdn.microsoft.com/en-us/library/ms536907(VS.85).aspx
  */
  window.onbeforeunload = function() {
      if (!validNavigation) {
         endSession();
      }
  }

  // Attach the event keypress to exclude the F5 refresh
  $(document).bind('keypress', function(e) {
    if (e.keyCode == 116){
      validNavigation = true;
    }
  });

  // Attach the event click for all links in the page
  $("a").bind("click", function() {
    validNavigation = true;
  });

  // Attach the event submit for all forms in the page
  $("form").bind("submit", function() {
    validNavigation = true;
  });

  // Attach the event click for all inputs in the page
  $("input[type=submit]").bind("click", function() {
    validNavigation = true;
  });
 
}

// Wire up the events as soon as the DOM tree is ready
$(document).ready(function() {
  wireUpEvents();
});