responseTextのXMLをJSONに変換する

function XMLToJSON(ajax)
{
  if (window.ActiveXObject)
  {
    var xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
    xmlDoc.async = false;
    xmlDoc.loadXML(ajax.responseText);
  }
  else if (window.DOMParser)
  {
    var xmlDoc = new DOMParser().parseFromString(
      ajax.responseText,
      "application/xml"
      );
  }
  else
  {
    return;
  }
  var loopParse = function(obj)
  {
    var res = {}, cacheTag = {};
    var ob = {}, att = obj.attributes;
    if (att != null && att.length != 0)
    {
      for (var a = 0, lenA = att.length; a < lenA; a++)
      {
        ob[att[a].nodeName.toLowerCase()] = att[a].nodeValue;
      }
      res._attr = ob;
    }
    
    if (obj.childNodes.length > 0)
    {
      for (var i = 0, len = obj.childNodes.length; i < len; i++)
      {
        var ch = obj.childNodes[i];
        if (ch.nodeType == 3)
        {
          if (ch.nodeValue.replace(/[\s|\t|\n]/g, "") == "" ||
              ch.nodeValue == null) continue;
          else return ch.nodeValue;
        }
        else if (ch.nodeType == 1)
        {
          (ch.tagName in cacheTag) ?
            cacheTag[ch.tagName].push(arguments.callee(ch)) :
            cacheTag[ch.tagName] = [arguments.callee(ch)];
        }
      }
    }
    else
    {
      return "";
    }
    for (var p in cacheTag)
    {
      (cacheTag[p].constructor == Array && cacheTag[p].length == 1) ?
        res[p] = cacheTag[p][0] : res[p] = cacheTag[p];
    }
    return res;
  }
  return loopParse(xmlDoc);
}