if (window.XMLHttpRequest)
      {// code for IE7+, Firefox, Chrome, Opera, Safari
      xmlhttp=new XMLHttpRequest();
      }
    else
      {// code for IE6, IE5
      xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
      }

      domena = location.hostname;

      var selectmenu=document.getElementById("id_l")
        selectmenu.onchange=function(){ //run some code when "onchange" event fires
         var chosenoption=this.options[this.selectedIndex] //this refers to "selectmenu"
         if (chosenoption.value!="nothing"){
             xmlhttp.open("GET", "http://"+ domena +"/ajax/town/?id_l="+chosenoption.value,true);
             xmlhttp.send();

              document.getElementById("townS").innerHTML = chosenoption.value;
              xmlhttp.onreadystatechange=function(){
                  if (xmlhttp.readyState==4 && xmlhttp.status==200){
                        document.getElementById("townS").innerHTML=xmlhttp.responseText;
                    }
              }
            }
        }