【图】Ajax读取XML实现动态下拉导航

根据客户的需要做一个产品的分类的导航菜单，以前使用ASP递归读取的。速度慢，而且消耗大量服务器资源。干脆改成AJAX+XML。共享出来和大家交流。希望各位能帮忙改进。
产品分类的XML文件
代码如下：

//id为自身id，pid为父级分类ID
?xml version="1.0" encoding="UTF-8" ?
Proot
       Item id="1" pid="0"1321系列/Item
       Item id="2" pid="1"43223系列/Item
/Proot

js代码
代码如下：

var root;
//FireFox不支持selectNodes方法，在网上找到这段代码解决了这个问题。兼容了IE和FireFox.
//创建selectNodes方法
if( document.implementation.hasFeature("XPath", "3.0") )
{
   // prototying the XMLDocument
   XMLDocument.prototype.selectNodes = function(cXPathString, xNode)
   {
      if( !xNode ) { xNode = this; }
      var oNSResolver = this.createNSResolver(this.documentElement)
      var aItems = this.evaluate(cXPathString, xNode, oNSResolver,
                   XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null)
      var aResult = [];
      for( var i = 0; i  aItems.snapshotLength; i++)
      {
         aResult[i] =  aItems.snapshotItem(i);
      }
      return aResult;
   }

   // prototying the Element
   Element.prototype.selectNodes = function(cXPathString)
   {
      if(this.ownerDocument.selectNodes)
      {
         return this.ownerDocument.selectNodes(cXPathString, this);
      }
      else{throw "For XML Elements Only";}
   }
}

function createXMLHttpRequest() {
    if (window.ActiveXObject) {
        oXmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else if (window.XMLHttpRequest) {
        oXmlHttp = new XMLHttpRequest();
    }

}

function CreateXMLDOM()
{
createXMLHttpRequest();
oXmlHttp.open( "GET", "XML路径", false ) ;
oXmlHttp.send(null) ;
root = oXmlHttp.responseXML.documentElement;
}
CreateXMLDOM()

function funCreatePullMenu(passPid,ChildId)
{

var currentItems = root.selectNodes("//Proot/Item[@pid = " + passPid + "]");
var iItems = currentItems.length;
var k=0;
if(iItems  0)
{


  var pdiv = document.createElement("DIV");
  pdiv.id="piv" + passPid;
  pdiv.className = "piv" + ChildId;
  pdiv.name = "piv" + passPid;
  if(passPid0)
  {
       pdiv.style.display="none";
    document.getElementById("div" + passPid).appendChild(pdiv);
  }
  else
  {
    document.getElementById("odiv").appendChild(pdiv);
  }
  for(var i = 0; i  iItems; i++)
  {
   var _id = currentItems[i].attributes[0].value;
   var newChild = document.createElement("DIV");
   newChild.id="div" + _id;
   newChild.className = "div" + ChildId;
   newChild.name = "div" + _id;

   var _v ;
   if(CheckPullMenu(_id))
   {
    _1= _id
    _v = "a href='javascript:showsubmenu(" + _1 + ")' " +currentItems[i].firstChild.data + "/a";
   }
   else
   {
    _v = "a href='ProductList.aspx?type=" + _id + "'"+ currentItems[i].firstChild.data +"/a";
   }

   newChild.innerHTML=_v;


   document.getElementById("piv" + passPid).appendChild(newChild);
   if(CheckPullMenu(_id))
   {
   funCreatePullMenu(_id,ChildId+1)
   }
  }
}
}

//检测是否有下级
function CheckPullMenu(passPid)
{

var currentItems = root.selectNodes("//Proot/Item[@pid = " + passPid + "]");
var iItems = currentItems.length;
if(iItems  0)
{
  return true;
}
    else
{
  return false;
}

}

//显示隐藏层
function showsubmenu(sid)
{
var whichEl = document.getElementById( "piv" +sid);
if (whichEl.style.display == "none")
  {
           whichEl.style.display="block";
  }
else
  {
     whichEl.style.display="none";
  }
}

使用方法：在网页中加入"div id="odiv"/div"。在body加入onload="funCreatePullMenu(0,0)"

最终效果：