用Ajax来控制书签和回退按钮的代码(5)

/** Our function that initializes when the page
    is finished loading. */
function initialize() {
   // initialize the DHTML History framework
   dhtmlHistory.initialize();

   // add ourselves as a DHTML History listener
   dhtmlHistory.addListener(handleHistoryChange);

   // if we haven't retrieved the address book
   // yet, grab it and then cache it into our
   // history storage
   if (window.addressBook == undefined) {
      // Store the address book as a global
      // object.
      // In a real application we would remotely
      // fetch this from a server in the
      // background.
      window.addressBook =
         ["Brad Neuberg 'bkn3@columbia.edu'",
          "John Doe 'johndoe@example.com'",
          "Deanna Neuberg 'mom@mom.com'"];

      // cache the address book so it exists
      // even if the user leaves the page and
      // then returns with the back button
      historyStorage.put("addressBook",
                         addressBook);
   }
   else {
      // fetch the cached address book from
      // the history storage
      window.addressBook =
               historyStorage.get("addressBook");
   }

　　处理历史变化的代码是简单的。在下面的代码中，当用户不论按下回退还是前进按钮handleHistoryChange 都被调用。我们得到新的地址(newLocation) 使用他更新我们的用户接口来改变状态，通过使用一个叫displayLocation的O'Reilly Mail的工具方法。

程序代码