my Ajax download code

<!--
String.prototype.getParam = function(name)
{
 var reg = new RegExp("(^|;|//s)"+name+"//s*://s*([^;]*)(//s|;|$)", "i");
 var str = this.replace(/(;[^:]+)(;|$)/g, function(a,b,c){return b.replace(/;/g, "/x0f")+c;});
 var r = str.match(reg);
 if (r!=null)
 return unescape(r[2].replace(/[/x0f]/g, ";"));
 return "";
}

function getObjectById(id)
{
 if (typeof(id) != "string" || id == "") return null;
 if (document.all) return document.all(id);
 if (document.getElementById) return document.getElementById(id);
 try {return eval(id);} catch(e){ return null;}
}

function MzTreeView(Tname)
{
 if(typeof(Tname) != "string" || Tname == "")
  throw(new Error(-1, 'no Class Name'));
 
 this.divider  = "_";
 this.url      = "#";
 this.target   = "_self";
 this.name     = Tname;
 this.index    = 0;
 this.nodes    = {};
 this.nodeFilePath = "";
 this.currentNode = null;

 var highLight = "#0A246A";
 var highLightText   = "#FFFFFF";
 var mouseOverBgColor= "#D4D0C8";

 this.createHTML = function(node, AtEnd)
 {
  var data = node.data;
  var id   = node.id;
  var url =  node.url;
  if(!url) url = this.url;
  if(data) url += (url.indexOf("/?")==-1?"/?":"&") + data;
  var HCN  = node.hasChild, isRoot = node.parentId=="0";
  if(isRoot && node.icon=="") node.icon = "root";
  if(node.icon=="") node.icon = HCN ? "folder" : "file";
   node.iconExpand  = HCN ? AtEnd ? "PM2" : "PM1" : AtEnd ? "L2" : "L1";
  if(node.id!="0" && !isRoot)  node.childAppend = node.parentNode.childAppend +
   "<IMG border='0' align='absmiddle' src='"+this.icons[(AtEnd?"empty":"L4")].src+"'>";

  var nodeHTML = "<DIV noWrap><SPAN onmouseover='this.style.backgroundColor=/""+
   mouseOverBgColor +"/"' onmouseout='this.style.backgroundColor=/"/"'><NOBR>"+
   (isRoot ? "" : node.parentNode.childAppend +
   "<IMG border='0' align='absmiddle' id='"+ Tname +"_expand_"+ id +"' "+
   (HCN ?"onclick=/""+ Tname +".expand('"+ id +"')/" " : "") +
   "src='"+ this.icons[node.iconExpand].src +"' style='cursor: hand'>")+
   "<SPAN oncontextmenu='return "+ Tname +".popupmenu(/""+ id +"/")' "
   // + " onclick=/""+ Tname +".focus('"+ id +"', true)/" " + (HCN ? " ondblclick=/""+ Tname +".expand('"+ id +"')/"" : "")
   + (HCN ? " onclick =/""+ Tname +".expand('"+ id +"', true);"+ Tname +".focus('"+ id +"', true);/"" : " onclick =/""+ Tname +".focus('"+ id +"', true);/" ")
   +">"+
   "<IMG border='0' align='absmiddle' id='"+ Tname +"_icon_"+ id +"' "+
   "src='"+ this.icons[node.icon].src +"'>"+
   "<A class='MzTreeview' id='"+ Tname +"_link_"+ id +"' ";
     nodeHTML += " target='"+ this.target + "' ";
        nodeHTML += " href='"+ url + "' ";
  nodeHTML += "title='"+ node.hint +"' onclick='"+
   "return "+ Tname +".click(/""+ id +"/");'>"+ node.text +"</A></NOBR>"+
   "</SPAN></SPAN></DIV>/r/n"; if(isRoot && node.text=="") nodeHTML = "";
   nodeHTML += "<SPAN id='"+ Tname +"_tree_"+ id +"' style='DISPLAY: none'></SPAN>";
  return nodeHTML;
 };
 
 var _d = "/x0f";
 this.node = {};
 this.node["0"] =
 {
  "id": "0",
  "path": "0",
  "isLoad": false,
  "childNodes": new Array(),
  "childAppend": "",
  "sourceIndex": "0",
  "childNodesFileName" : ""
 };

    this.XMLHttpLoadFile = function(url,id)
    {
        var httpRequest;
        if (typeof XMLHttpRequest != 'undefined') {
            httpRequest = new XMLHttpRequest();
        }
        else if (typeof ActiveXObject != 'undefined') {
            httpRequest = new ActiveXObject('Microsoft.XMLHTTP');
        }
        if (httpRequest) {
            httpRequest.open('GET', url, false);
            httpRequest.send(null);
            if(httpRequest.status == 200)
            {
                var textInfo = httpRequest.responseText;
                eval(textInfo);
            }
        }
    }

 this.load = function(id,sign)
 {
  var me  = this, node = this.node[id];
        if(sign && (id > 0))
        {
   setTimeout(me.name +".load('"+ id +"',false)", 1);
   getObjectById(me.name +"_tree_"+ id).innerHTML = node.childAppend +
   "<IMG border='0' align='absmiddle' src='"+this.icons["L2"].src+"'>"+
   "<IMG border='0' align='absmiddle' src='"+this.icons["file"].src+"'>"+
   "<span style='background-Color: "+ highLight +"; color: "+ highLightText +
   "; font-size: 9pt'>"+ unescape("%u52A0%u8F7D%u4E2D") +"...</span>";
   return;
        }
       
  if(!node.isLoad)
  {
      if((node.childNodesFileName)&&(node.childNodesFileName != "undefined")&&(node.childNodesFileName.length > 0))
      {
          this.XMLHttpLoadFile(node.childNodesFileName,id);
          node.isLoad = true;
      }
  }

  var sid = node.sourceIndex.substr(node.sourceIndex.indexOf(this.divider) + this.divider.length);
  var str = "(^|"+ _d +")"+ sid + this.divider +"[^"+ _d + this.divider +"]+("+ _d +"|$)";
  var reg = new RegExp(str, "g"), cns = this.names.match(reg), tcn = this.node[id].childNodes;
  if (cns){
   reg = new RegExp(_d, "g");
   for(var i=0; i<cns.length; i++)
   {
       var tmp = cns[i].replace(reg, "");
       tcn[tcn.length] = this.nodeInit(tmp, id);
   }
  }
  node.isLoad = true; if(node.id=="0") return;
  this.drawNode(id);
 };

 this.nodeInit = function(sourceIndex, parentId)
 {
  this.index++;
  var param = this.nodes[sourceIndex];
  var hint  = param.getParam("hint");
  var text  = param.getParam("text");
  var childNodesFileNameValue = param.getParam("childNodesFileName");
  var sid   = sourceIndex.substr(sourceIndex.indexOf(this.divider) + this.divider.length);
  
  this.node[this.index] = {
   "id"    : this.index,
   "text"  : text,
   "hint"  : hint ? hint : text,
   "icon"  : param.getParam("icon"),
   "path"  : this.node[parentId].path + this.divider + this.index,
   "isLoad": false,
   "isExpand": false,
   "parentId": parentId,
   "parentNode": this.node[parentId],
   "sourceIndex" : sourceIndex,
   "childAppend" : "",
   "childNodesFileName" : childNodesFileNameValue ? (this.nodeFilePath + childNodesFileNameValue) : "",
   "url"   : param.getParam("url"),
   "data"   : param.getParam("data")
   
  };
  if(childNodesFileNameValue)
  {
      this.node[this.index].hasChild = true;
  }
  else
  {
      this.node[this.index].hasChild = this.names.indexOf(_d + sid + this.divider)>-1;
  }
  if(this.node[this.index].hasChild)  this.node[this.index].childNodes = new Array();
  this.nodes[sourceIndex] = this.index;
  return this.node[this.index];
 };

 this.drawNode = function(id)
 {
  var tcn     = this.node[id].childNodes, str = "";
  for (var i=0; i<tcn.length; i++) str += this.createHTML(tcn[i], i==tcn.length-1);
  getObjectById(Tname +"_tree_"+ id).innerHTML = str;
 };

 this.getPath= function(id)
 {
  var A = new Array(); A[0] = id, pid=id;
  while(id!="0" && id!="")
  {
   var str = "(^|"+_d+")([^"+_d+ this.divider +"]+"+ this.divider + id +")("+_d+"|$)";
   var ids = this.names.match(new RegExp(str, "g"));
   if(ids)
   {
    id = ids[0].replace(_d, "").split(this.divider)[0];
    A[A.length] = id;
   } else break;
  }
  return A.reverse();
 };

 this.focus      = function(id, onlySimpleFocus)
 {
  if(!this.currentNode) this.currentNode=this.node["0"]; if(!onlySimpleFocus){
  if(typeof(this.node[id])=="undefined") var apid = this.getPath(id);
  else var apid = this.node[id].path.split(this.divider);
  for(var i=0; i<apid.length-1; i++) this.expand(apid[i], true);}

  var a = getObjectById(Tname +"_link_"+ id); if (a) { a.focus();// alert("focus "+ id);
  var link = getObjectById(Tname +"_link_"+ this.currentNode.id);
  if(link)with(link.style){color="";   backgroundColor="";}
  with(a.style){color = highLightText; backgroundColor = highLight;}
  this.currentNode= this.node[id];}
 };
 
 this.expand   = function(id, sureExpand)
 {
  var node  = this.node[id];
  if (sureExpand && node.isExpand) return;
  var area    = getObjectById(Tname +"_tree_"+ id);
  if (area)
  {
      var icon  = this.icons[node.icon];
   var iconE = this.iconsExpand[node.icon];
   var exp   = this.icons[node.iconExpand];
   var expE  = this.iconsExpand[node.iconExpand];
   var Bool  = node.isExpand = sureExpand || area.style.display == "none";

   var img   = getObjectById(Tname +"_icon_"+ id);
   if (img)  img.src = !Bool ? icon.src :typeof(iconE)=="undefined" ? icon.src : iconE.src;
   
   var img   = getObjectById(Tname +"_expand_"+ id);
   if (img)  img.src = !Bool ? exp.src : typeof(expE) =="undefined" ? exp.src  : expE.src;
   
   if(!Bool && this.currentNode.path.indexOf(node.path)==0)
   {
    this.focus(id, true);
    this.click(id);
   }
   area.style.display = Bool ? "block" : "none";
   if(!node.isLoad)
   {
       this.load(id,true);
   }
  }
 };
 
 
 this.toString = function()
 {
  var a = new Array(); for (id in this.nodes) a[a.length] = id;
  this.names = a.join(_d + _d); this.load("0",true);
  var rootCN = this.node["0"].childNodes;
  var str = "<A id='"+ Tname +"_RootLink' href='#' style='DISPLAY: none'></A>";
  if(rootCN.length>0)
  {
   for(var i=0; i<rootCN.length; i++) str += this.createHTML(rootCN[i], i==rootCN.length-1);
   setTimeout(Tname +".expand('"+ rootCN[0].id +"', true); "+
    Tname +".focus('"+ rootCN[0].id +"'); "+ Tname +".atRootIsEmpty()",10);
  }
  return str;
 };
}

MzTreeView.prototype.setIconPath  = function(path)
{
 this.icons    = {
  L0        : 'L0.gif',  //┏
  L1        : 'L1.gif',  //┣
  L2        : 'L2.gif',  //┗
  L3        : 'L3.gif',  //━
  L4        : 'L4.gif',  //┃
  PM0       : 'P0.gif',  //＋┏
  PM1       : 'P1.gif',  //＋┣
  PM2       : 'P2.gif',  //＋┗
  PM3       : 'P3.gif',  //＋━
  empty     : 'L5.gif',     //blank
  root      : 'root.gif',   // root
  folder    : 'folder.gif', // folder
  file      : 'file.gif',   // file

  event     : 'event.gif',
  object    : 'object.gif',
  behavior  : 'behavior.gif',
  property  : 'property.gif',
  method    : 'method.gif',
  collection: 'collection.gif',

     exit      : 'exit.gif'
 };

  this.iconsExpand = {
    PM0       : 'M0.gif',     //－┏
    PM1       : 'M1.gif',     //－┣
    PM2       : 'M2.gif',     //－┗
    PM3       : 'M3.gif',     //－━
    folder    : 'folderopen.gif',

    exit      : 'exit.gif'
  };
  for(var i in this.icons)
  {
    var tmp = this.icons[i];
    this.icons[i] = new Image();
    this.icons[i].src = path + tmp;
  }
  for(var i in this.iconsExpand)
  {
    var tmp = this.iconsExpand[i];
    this.iconsExpand[i]=new Image();
    this.iconsExpand[i].src = path + tmp;
  }
}

MzTreeView.prototype.atRootIsEmpty = function()
{
  var RCN = this.node["0"].childNodes;
  for(var i=0; i<RCN.length; i++)
  {
    if(RCN[i].text=="")
    {
      var node = RCN[i].childNodes[0], HCN  = node.hasChild;
      node.iconExpand  =  RCN[i].childNodes.length>1 ? HCN ? "PM0" : "L0" : HCN ? "PM3" : "L3"
      getObjectById(this.name +"_expand_"+ node.id).src = this.icons[node.iconExpand].src;
    }
  }
};

MzTreeView.prototype.popupmenu  = function(id)
{
  try
  {
    if(this.popupMenu)
    {
      if(id)
      {
        this.popupMenu.data = this.node[id].data;
        this.popupMenu.treeviewitem = this.node[id];
      }
      for(var i=0; i<this.popupMenu.items.length; i++)
      {
        if(this.popupMenu.items[i].bind != "")
        this.popupMenu.items[i].bind = Tname +"_tree_"+ Tname;
      }
      this.popupMenu.show(window.event, window.event.srcElement);
      return false;
    }
    else return true;
  }catch(e){}
};

MzTreeView.prototype.click    = function(id)
{
  if( (this.node[id].url == this.url) || ((this.node[id].url == "")&&(this.node[id].data == ""))) return false;
  return true;
};
// -->