function createXmlHttpRequestObject() 
{
  var xmlHttp;
  // pre vsetko okrem IE
  try
  {
    xmlHttp = new XMLHttpRequest();
  }
  catch(e)
  {
    // pre IE a starsie
    var XmlHttpVersions = new Array("MSXML2.XMLHTTP.6.0",
                                    "MSXML2.XMLHTTP.5.0",
                                    "MSXML2.XMLHTTP.4.0",
                                    "MSXML2.XMLHTTP.3.0",
                                    "MSXML2.XMLHTTP",
                                    "Microsoft.XMLHTTP");
    for (var i=0; i<XmlHttpVersions.length && !xmlHttp; i++) 
    {
      try 
      { 
        xmlHttp = new ActiveXObject(XmlHttpVersions[i]);
      } 
      catch (e) {}
    }
  }
  // ak inicializacia zlyhala
  if (!xmlHttp)
    alert("Chyba: Vas prehliadac zrejme nepodporuje vyuzivanu technologiu. Odporucame pouzivat Mozillu Firefox, alebo MSIE 6+.");
  else 
    return xmlHttp;
}


function drom_registracia_dostupnost_username(parametre, obsluha, headers)
{
	var method	= 'POST';
	var url		= ('http://www.drom.sk/misc/ajax/overenie-dostupnosti-uzivatelskeho-mena.cgi');
	
    var xmlhttp = createXmlHttpRequestObject();
    if (!xmlhttp) {
        return false;
    }
    xmlhttp.open(method, url, false);
    if (headers) {
        for (var key in headers) {
            xmlhttp.setRequestHeader(key, headers[key]);
        }
    }
    var content	= 'ok=1';
    if (parametre) {
   		for (var key in parametre) {
            	content += ('&'+encodeURI(key)+'='+encodeURI(parametre[key]));
        }
    }
    xmlhttp.send(content);
    obsluha(xmlhttp.responseText);
    return true;
}