function getZipcode(zipcode){
   
   var selectFeld = document.getElementById("ort");
   var oldOptions = selectFeld.options;
   for(i = (oldOptions.length - 1); i > 0; i--){selectFeld.remove(i);}
   
  
      var ajax = new Ajax.Updater(
      {success : ''},
      "ajax.php?file=zipcode&zc="+zipcode,
      {
         method:'get',
         onFailure: function (){alert("da lief wos schief!")},
         onSuccess: function (request){
            var get = request.responseText;
            var obj = eval("("+get+")");
            
            for (i = 0; i < obj.postalcodes.length; i++){
               oldOptions[i] = new Option(obj.postalcodes[i]["placeName"],obj.postalcodes[i]["placeName"],false,false);               
            }
            
         },
         asynchronous: true
      });
   
   
}