Etwas

function createRequestObject() {
   var ro;
   var browser = navigator.appName;
   if(browser == "Microsoft Internet Explorer"){
      ro = new ActiveXObject("Microsoft.XMLHTTP");
   } else {
      ro = new XMLHttpRequest();
   }
   return ro;
}

var http = createRequestObject();

function suche(action, target) {
   if (action.length > 2) {
         http.open('POST', '/ajax/returnCompaniesLight.php?query='+action+'&target='+target, true);
         http.onreadystatechange = handleResponse_search(target);
         http.send(null);
   }
}

function handleResponse_search(target) {
        if (http.readyState == 4) {
            var response = http.responseText;
alert(response);
            document.getElementById(target).innerHTML = "<strong>Bitte w&auml;hlen Sie</strong> <p>";
            document.getElementById(target).innerHTML = document.getElementById(target).innerHTML+response;
            document.getElementById(target).innerHTML = document.getElementById(target).innerHTML+"</p>";
            document.getElementById(target).style.display='block';
       }
}