How do I correctly detect orientation change using Phonegap on iOS?

I found this orientation test code below looking for JQTouch reference material. This works correctly in the iOS simulator on mobile Safari but doesn’t get handled correctly in Phonegap. My project is running into the same issue that is killing this test page. Is there a way to sense the orientation change using JavaScript in Phonegap?

window.onorientationchange = function() {
  /*window.orientation returns a value that indicates whether iPhone is in portrait mode, landscape mode with the screen turned to the
    left, or landscape mode with the screen turned to the right. */
  var orientation = window.orientation;
  switch (orientation) {
    case 0:
      /* If in portrait mode, sets the body's class attribute to portrait. Consequently, all style definitions matching the body[class="portrait"] declaration
         in the iPhoneOrientation.css file will be selected and used to style "Handling iPhone or iPod touch Orientation Events". */
      document.body.setAttribute("class", "portrait");

      /* Add a descriptive message on "Handling iPhone or iPod touch Orientation Events"  */
      document.getElementById("currentOrientation").innerHTML = "Now in portrait orientation (Home button on the bottom).";
      break;

    case 90:
      /* If in landscape mode with the screen turned to the left, sets the body's class attribute to landscapeLeft. In this case, all style definitions matching the
         body[class="landscapeLeft"] declaration in the iPhoneOrientation.css file will be selected and used to style "Handling iPhone or iPod touch Orientation Events". */
      document.body.setAttribute("class", "landscape");

      document.getElementById("currentOrientation").innerHTML = "Now in landscape orientation and turned to the left (Home button to the right).";
      break;

    case -90:
      /* If in landscape mode with the screen turned to the right, sets the body's class attribute to landscapeRight. Here, all style definitions matching the
         body[class="landscapeRight"] declaration in the iPhoneOrientation.css file will be selected and used to style "Handling iPhone or iPod touch Orientation Events". */
      document.body.setAttribute("class", "landscape");

      document.getElementById("currentOrientation").innerHTML = "Now in landscape orientation and turned to the right (Home button to the left).";
      break;
  }
}

This is what I do:

function doOnOrientationChange() {
    switch(window.orientation) {  
      case -90: case 90:
        alert('landscape');
        break; 
      default:
        alert('portrait');
        break; 
    }
}
  
window.addEventListener('orientationchange', doOnOrientationChange);
  
// Initial execution if needed
doOnOrientationChange();

Update May 2019: window.orientation is a deprecated feature and not supported by most browsers according to MDN. The orientationchange event is associated with window.orientation and therefore should probably not be used.