使用javaScript做了个列表菜单,有个简单的问题,在线等

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<link rel="stylesheet" type="text/css" href="">
<script type="text/javascript" src=""></script>
<script language="javascript" type="text/javascript"></script>
<style>
<!--
#foldheader{cursor:hand ; font-weight:bold ;
list-style-image:url(fold.gif)}
#foldinglist{list-style-image:url(list.gif)}
//-->
</style>
<script language="JavaScript1.2">
<!--
/** 
 *  Based on Folding Menu Tree 
 *  Dynamic Drive (www.dynamicdrive.com)
 *  For full source code, installation instructions,
 *  100's more DHTML scripts, and Terms Of
 *  Use, visit dynamicdrive.com
 *
 *  Updated to support arbitrarily nested lists
 *  by Mark Quinn (@robocast.com) November 2nd 1998
 */var head="display:''"
img1=new Image()
img1.src="fold.gif"
img2=new Image()
img2.src="open.gif"function change(){
   if(!document.all)
      return
   if (event.srcElement.id=="foldheader") {
      var srcIndex = event.srcElement.sourceIndex
      var nested = document.all[srcIndex+1]
      if (nested.style.display=="none") {
         nested.style.display=''
         event.srcElement.style.listStyleImage="url(open.gif)"
      }
      else {
         nested.style.display="none"
         event.srcElement.style.listStyleImage="url(fold.gif)"
      }
   }
}document.onclick=change//-->
</script>
</HEAD><BODY>
<ul>
   <li id="foldheader">News</li>
   <ul id="foldinglist" style="display:none">
      <li><a href="../../../www.cnn.com/index.html">CNN</a></li>
      <li><a href="../../../www.abcnews.com/index.html">ABC News</a></li>
      <li><a href="../../../www.vancouversun.com/index.html">Vancouver Sun</a></li>
   </ul>   <li id="foldheader">Games</li>
   <ul id="foldinglist" style="display:none">
      <li><a href="../../../www.gamespot.com/index.html">GameSpot</a></li>
      <li><a href="../../../www.happypuppy.com/index.html">Happy Puppy</a></li>
      <li><a href="../../../www.gamecenter.com/index.html">Game Center</a></li>
   </ul>   <li id="foldheader">Software</li>
   <ul id="foldinglist" style="display:none">
      <li><a href="../../../www.download.com/index.html">outer 1</a></li>
      <li><a href="../../../www.hotfiles.com/index.html">outer 2</a></li>
      <li id="foldheader">Nested</li>
      <ul id="foldinglist" style="display:none">
         <li><a href="../../../www.windows95.com/index.html">nested 1</a></li>
         <li><a href="../../../www.shareware.com/index.html">nested 2</a></li>
      </ul>
      <li><a href="../../../www.windows95.com/index.html">outer 3</a></li>
      <li><a href="../../../www.shareware.com/index.html">outer 4</a></li>
   </ul>
</ul>
<script language="JavaScript1.2">
<!--
/**
 * Get cookie routine by Shelley Powers 
 * ([email protected])
 */
function get_cookie(Name) {
  var search = Name + "="
  var returnvalue = "";
  if (document.cookie.length > 0) {
    offset = document.cookie.indexOf(search)
    // if cookie exists
    if (offset != -1) { 
      offset += search.length
      // set index of beginning of value
      end = document.cookie.indexOf(";", offset);
      // set index of end of cookie value
      if (end == -1) end = document.cookie.length;
      returnvalue=unescape(document.cookie.substring(offset, end))
      }
   }
  return returnvalue;
}if (get_cookie(window.location.pathname) != ''){
  var openresults=get_cookie(window.location.pathname).split(" ")
  for (i=0 ; i < openresults.length ; i++){
    foldinglist[openresults[i]].style.display=''
    document.all[foldinglist[openresults[i]].sourceIndex -
1].style.listStyleImage="url(open.gif)"
  }
}if (document.all){
  var nodelength=foldinglist.length-1
  var nodes=new Array(nodelength)
  var openones=''
}function check(){
  for (i=0 ; i <= nodelength ; i++){
    if (foldinglist[i].style.display=='')
       openones=openones + " " + i
  }
  document.cookie=window.location.pathname+"="+openones
}if (document.all)
  document.body.onunload=check
//-->
</script>
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