var xmlHttp;

  function vytvorXmlHttp() {
    if (window.XMLHttpRequest) {
       xmlHttp = new XMLHttpRequest();
     } else if (window.ActiveXObject) {
        try {
          xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (error) {
          xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
     }  
  }