var http_request = false;
    function abfrage(url) {
 
        http_request = false;
 
        if (window.XMLHttpRequest) { //Abfrage bei Firefox & Co
            http_request = new XMLHttpRequest();
        } else if (window.ActiveXObject) { // Internet Explorer
            try {
                http_request = new ActiveXObject('Msxml2.XMLHTTP');
            } catch (e) {
                try {
                    http_request = new ActiveXObject('Microsoft.XMLHTTP');
                } catch (e) {}
            }
        }
 
        if (!http_request) {
            alert('Ende :( Kann keine XMLHTTP-Instanz erzeugen');
            return false;
        }
        http_request.open('GET', url, true);
        http_request.onreadystatechange = ausgabe;
        http_request.send(null);
 
    }
 
    function ausgabe() {
        if (http_request.readyState == 4) {
              var answer = http_request.responseText;
              if(document.getElementById('meldung').innerHTML != answer){
                document.getElementById('meldung').innerHTML = answer;
              }
              else{
                document.getElementById('meldung').innerHTML = '';
              }
        }
 
    }