var receiveReq = false;

if (window.XMLHttpRequest)
{
        receiveReq = new XMLHttpRequest(); //Not IE
}
else if(window.ActiveXObject("Microsoft.XMLHTTP"))
{
        receiveReq = new ActiveXObject("Microsoft.XMLHTTP"); //IE
}
else
{
         alert("Ihr Browser unterstützt kein AJAX!");
}

function hol(datei)
{
         if (receiveReq.readyState == 4 || receiveReq.readyState == 0)
         {
                receiveReq.open("GET", "kat/"+datei,true);
                receiveReq.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
                receiveReq.onreadystatechange = mach;
                receiveReq.send(null);
         }
}
function mach()
{
         var obj_main = document.getElementById('result');
         if ((receiveReq.readyState == 4))
         {
                 obj_main.innerHTML = receiveReq.responseText;
                delLoader();
        }
         else
         {
                 getLoader();
         }
}

function getLoader()
{

        document.getElementById('loader').style.visibility = "visible";
}
function delLoader()
{

        document.getElementById('loader').style.visibility = "hidden";
}