用Ajax来控制书签和回退按钮的代码

haskey()检查他是否存在。

程序代码
window.onload = initialize;

function initialize() {
  // initialize the DHTML History
  // framework
  dhtmlHistory.initialize();

  // subscribe to DHTML history change
  // events
  dhtmlHistory.addListener(historyChange);

  // if this is the first time we have
  // loaded the page...
  if (dhtmlHistory.isFirstLoad()) {
    debug("Adding values to browser "
          + "history", false);
    // start adding history
    dhtmlHistory.add("helloworld",
                     "Hello World Data");
    dhtmlHistory.add("foobar", 33);
    dhtmlHistory.add("boobah", true);

    var complexObject = new Object();
    complexObject.value1 =
                  "This is the first value";
    complexObject.value2 =
                  "This is the second data";
    complexObject.value3 = new Array();
    complexObject.value3[0] = "array 1";
    complexObject.value3 = "array 2";

    dhtmlHistory.add("complexObject",
                     complexObject);

    // cache some values in the history
    // storage
    debug("Storing key ''fakeXML'' into "
          + "history storage", false);
    var fakeXML =
      ''<?xml version="1.0" ''
      +      ''encoding="ISO-8859-1"?>''
      +      ''<foobar>''
      +         ''<foo-entry/>''
      +      ''</foobar>'';
    historyStorage.put("fakeXML", fakeXML);
  }

  // retrieve our values from the history
  // storage
  var savedXML =
              historyStorage.get("fakeXML");
  savedXML = prettyPrintXml(savedXML);
  var hasKey =
           historyStorage.hasKey("fakeXML");
  var message =
    "historyStorage.hasKey(''fakeXML'')="
&