var request;
var selected_country;
var zip_code;

function checkCityName(){
   //alert(oID);
   selected_country = document.getElementById('sel_country').options[document.getElementById('sel_country').options.selectedIndex].value;
   zip_code = document.getElementById('zip_code').value;
   if(selected_country != "" && zip_code.length >= 4){
      request = GetXmlHttpObject()
      if (request == null){
        alert ("Your browser does not support XML HTTP Request");
        return;
      }
      var url = "zip_coder.php";
      url = url + "?zc=" + zip_code;
      url = url + "&cid=" + selected_country;
      url = url + "&sid=" + Math.random();
      //alert(url);
      xmlResponseText = 'false';
      request.open('GET', url, true);
      request.send(null);
      request.onreadystatechange = interpretRequest;
      return true;
   }else{
      //alert('Kein Land gewählt');
      return false;
   }
}

// Request auswerten
function interpretRequest() {
        switch (request.readyState) {
                // wenn der readyState 4 und der request.status 200 ist, dann ist alles korrekt gelaufen
                case 4:
                        if (request.status != 200) {
                                alert("Der Request wurde abgeschlossen, ist aber nicht OK\nFehler:"+request.status+'\nResponse: '+xmlResponseText);
                        } else {
                                var content = request.responseText;
                                // den Inhalt des Requests in das <div> schreiben
                                document.getElementById('zip_city').value = trim(content);
                        }
                        break;
                default:
                        break;
        }
}

function GetXmlHttpObject(){
   if (window.XMLHttpRequest){
     // code for IE7+, Firefox, Chrome, Opera, Safari
     return new XMLHttpRequest();
   }
   if (window.ActiveXObject){
     // code for IE6, IE5
     return new ActiveXObject("Microsoft.XMLHTTP");
   }
   return null;
}

function trim(stringToTrim) {
        return stringToTrim.replace(/^\s+|\s+$/g,"");
}

function ltrim(stringToTrim) {
        return stringToTrim.replace(/^\s+/,"");
}

function rtrim(stringToTrim) {
        return stringToTrim.replace(/\s+$/,"");
}