JS解析XML

朋友很急，正好我沒什麼事就一起幫忙，順便學一學。
前一段還以為js上解析xml是ajax的功勞，其實不然。
朋友的問題如下：
Dear Applicant,
Thank you very much for your interest in this position. Would you please send me some _fragment_ of code and designment document that you've worked on in your past projects?  That will helps us better evaluate your applicaiton.
We hope you can demonstrate your experience/learning ability by finishing the assignment below. It'll be a jscript function to transform a given format of XML input to another XML format.
The input would be like:

<?xml version="1.0"?>
<menu xmlns="">
    <menuitem>
        <node>1</node>
        <parent>1</parent>
        <name>parent</name>
    </menuitem>
    <menuitem>
        <node>2</node>
        <parent>1</parent>
        <name>1st child</name>
    </menuitem>
    <menuitem>
        <node>3</node>
        <parent>1</parent>
        <name>2nd child</name>
    </menuitem>
    <menuitem>
        <node>4</node>
        <parent>2</parent>
        <name>grantchild</name>
    </menuitem>
</menu>

The output would be like:
<?xml version="1.0"?>
<menu xmlns="">
    <menuitem>
        <name>parent</name>
        <menuitem>
            <name>1st child</name>
            <menuitem>
                <name>grand child</name>
            </menuitem>
        </menuitem>
        <menuitem>
            <name>2nd child</name>
        </menuitem>
    </menuitem>
</menu>
In the input format, tag "node" and "parent" specifies the structure of the tree, while "name" and others tags should be copied to the output format.  Therefore, the code should be able to handle the following fragment of XML:
<menuitem>
        <node>2</node>
        <parent>1</parent>
        <name>1st child</name>
        <lastName>Dai</lastName>
        <firstName>Kun</firstName>
</menuitem>
Thank you again for your time, and please reply this email after you get it.
我只幫忙解析，後面嗎，只提供思路：解析的元素封裝成js的object，之後處理邏輯就和java一樣了。
解析代碼：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!--
function loadXml(){
  var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
     //try //Internet Explorer
       //{
      // xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
      // }
      // catch(e)
      // {
      // try //Firefox, Mozilla, Opera, etc.
     // {
     // xmlDoc=document.implementation.createDocument("","",null);
     // }
      //   catch(e) {alert(e.message)}
        //   }
   xmlDoc.async="false";//取消非同步載入
   xmlDoc.load("a.xml");
   //xmlDoc.loadXmlString(字串);如果xml的內容是一個字串比如<x>1</x>可以用此方法
   //var items = xmlDoc.selectNodes("/menu/menuitem");
   //alert(items.length);
  // for(var i=0;i<items.length;i++){
  // alert(xmlDoc.selectSingleNode("/menu/menuitem["+i+"]/node").text);
  // alert(xmlDoc.selectSingleNode("/menu/menuitem["+i+"]/parent").text);
  // alert(xmlDoc.selectSingleNode("/menu/menuitem["+i+"]/name").text);
   //}
  //方法2
  var items = xmlDoc.getElementsByTagName("menuitem");
   alert(items.length);
   for(var i=0;i<items.length;i++){
   var x = items.firstChild;
   alert(x.getAttribute("title"));//取得標籤上的屬性，如<x title="a"></x>取得title的值'a'
   alert(x.text);//或者xmldoc.getElementsByTagName("node").text
   alert(x.nextSibling.text);//nextSibling方法是取得下一個node
   alert(x.nextSibling.nextSibling.text);
   }
  }
  function getNode(doc, xpath) {
  varretval = "";
  var value = doc.selectSingleNode(xpath);
  if (value) retval = value.text;
  return retval;
    }
//-->
</SCRIPT>
</HEAD>

<BODY>
<input type="button" onclick="loadXml()" value = "ok">
</BODY>
</HTML>
用了兩種方法，第一種是通過網上google的例子依賴於selectSingleNode和selectNodes方法，
個人覺得通用性很難實現，如果實現的話，需要的是封裝路徑，而且事先要知道整個xml檔案的完整結構。
第二種方法，是我從w3school上學到的，在被xmlDoc載入之後，xml部分應該就具備了頁面元素的特性，所以通過getElementsXX等方法就可以去做，在w3school上學到的竅門，拿到firstChild之後後面的元素就用nextsibling，當然需要加判斷的，測試的關係沒有加。
這次發現，對與html沒有足夠充分的瞭解而去研究js架構是比較困難的，所以w3school繼續學習中。