用Ajax来控制书签和回退按钮的代码

   // DHTML history change
   displayLocation(newLocation, historyData);
}

/** Displays the given location in the
    right-hand side content area. */
function displayLocation(newLocation,
                         sectionData) {
   // get the menu element that was selected
   var selectedElement =
            document.getElementById(newLocation);

   // clear out the old selected menu item
   var menu = document.getElementById("menu");
   for (var i = 0; i < menu.childNodes.length;
                                          i++) {
      var currentElement = menu.childNodes[i];
      // see if this is a DOM Element node
      if (currentElement.nodeType == 1) {
         // clear any class name
         currentElement.className = "";
      }                                      
   }

   // cause the new selected menu item to
   // appear differently in the UI
   selectedElement.className = "selected";

   // display the new section in the right-hand
   // side of the screen; determine what
   // our sectionData is

   // display the address book differently by
   // using our local address data we cached
   // earlier
   if (newLocation == "addressbook") {
      // format and display the address book
      sectionData = "<p>Your addressbook:</p>";
      sectionData += "<ul>";

      // fetch the address book from the cache
      // if we don't have it yet
      if (window.addressBook == undefined) {
         window.addressBook =
               historyStorage.get("addressBook");
      }

      // format the address book for display
      for (var i = 0;