/**
* Returns an XMLHttp instance to use for asynchronous
* downloading. This method will never throw an exception, but will
* return NULL if the browser does not support XmlHttp for any reason.
* @return {XMLHttpRequest|Null}
*/
function createXmlHttpRequest() {
 try {
   if (typeof ActiveXObject != 'undefined') {
     return new ActiveXObject('Microsoft.XMLHTTP');
   } else if (window["XMLHttpRequest"]) {
     return new XMLHttpRequest();
   }
 } catch (e) {
   changeStatus(e);
 }
 return null;
};

/**
* This functions wraps XMLHttpRequest open/send function.
* It lets you specify a URL and will call the callback if
* it gets a status code of 200.
* @param {String} url The URL to retrieve
* @param {Function} callback The function to call once retrieved.
*/
function downloadUrl(url, callback) {
 var status = -1;
 var request = createXmlHttpRequest();
 if (!request) {
   return false;
 }

 request.onreadystatechange = function() {
   if (request.readyState == 4) {
     try {
       status = request.status;
     } catch (e) {
       // Usually indicates request timed out in FF.
     }
     if (status == 200) {
       callback(request.responseXML, request.status);
       request.onreadystatechange = function() {};
     }
   }
 }
 request.open('GET', url, true);
 try {
   request.send(null);
 } catch (e) {
   changeStatus(e);
 }
};

/**
 * Parses the given XML string and returns the parsed document in a
 * DOM data structure. This function will return an empty DOM node if
 * XML parsing is not supported in this browser.
 * @param {string} str XML string.
 * @return {Element|Document} DOM.
 */
function xmlParse(str) {
// Test for W3C feature 
/*  if (DOMParser) {
var dpDOMParser = new DOMParser(); 
return dpDOMParser.parseFromString(str, "text/xml");
} else { // IE 8 and previous or IE 9 when *not* in Standards mode...
var xdDoc = new ActiveXObject("Microsoft.XMLDOM"); 
xdDoc.async="false";
xdDoc.loadXML(str); 
return xdDoc;
}  */



    try
    {
        var xmlParser = new DOMParser();
        var xmlDoc = xmlParser.parseFromString(str, "text/xml");
    }
    catch(Err)
    {
        try
        {
            var xmlDoc= new ActiveXObject("Microsoft.XMLDOM");
            xmlDoc.async="false";
            xmlDoc.loadXML(str);
        }
        catch(Err)
        {
            //window.alert("Browser does not support XML parsing.");
            //return false;
        }
    }

    return xmlDoc;





/* 
try //Internet Explorer
  {
  xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
  xmlDoc.async="false";
  xmlDoc.loadXML(str);
  }
catch(e)
  {
  try //Firefox, Mozilla, Opera, etc.
  {
  var parser=new DOMParser();
  xmlDoc=parser.parseFromString(str,"text/xml");
  }
  catch(e)
  {
  alert(e.message);
  return;
  }
} */



/*    if (typeof ActiveXObject != 'undefined' && typeof GetObject != 'undefined') {
    var doc = new ActiveXObject('Microsoft.XMLDOM');
    doc.loadXML(str);
	//Response.Write VarType(str)
    return doc;
  }

  if (typeof DOMParser != 'undefined') {
    return (new DOMParser()).parseFromString(str, 'text/xml');
  }

  return createElement('div', null);  */
}

/**
 * Appends a JavaScript file to the page.
 * @param {string} url
 */
function downloadScript(url) {
  var script = document.createElement('script');
  script.src = url;
  document.body.appendChild(script);
}