How do I disable Android Back button on one page and change to exit button on every other page

How do I disable Android Back button on one page and change to exit button on every other page

Hello community,

I am developing an Android application using Phonegap that interacts with my Drupal site. I have re-assigned the Android "Back" button to prompt the user to log off from the Drupal server however, I just want it disabled on the login page (for obvious reasons). I can get it to work but only until the user logs out then once on the login page the button remains re-assigned as a logoff button. Here's the code I have so far:

  2. <head>
  3.          <script>
  4.         /* Wait until device is ready to re-assign Back button */
  5.         document.addEventListener("deviceready", onDeviceReady, false);
  6.         function onDeviceReady() {
  7.             document.addEventListener("backbutton", onBackKeyPress, false);
  8.         }
  9.         function onBackKeyPress() {
  10.             /* If the current page is the login page, disable the button completely (aka do nothing) */
  11.             if ($.mobile.activePage.attr('id') == 'login_page') {
  12.             }

  14.             /* Else, execute log off code */
  15.             else {
  16.                 if (confirm("Are you sure you want to logout?")) {
  17.                     /* Here is where my AJAX code for logging off goes */
  18.                 }
  19.                 else {
  20.                     return false;
  21.                 }
  22.             }
  23.         }
  24.         </script>
  25. </head>

The problem is that the Back button doesn't get re-assigned. I cannot figure out a way to re-run the above code when the user logs out and ends up back on the login page.

If anybody is willing to provide a solution for this I will be very grateful!