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