function Inint_AJAX() {
   try { return new ActiveXObject("Msxml2.XMLHTTP");  } catch(e) {} //IE
   try { return new ActiveXObject("Microsoft.XMLHTTP"); } catch(e) {} //IE
   try { return new XMLHttpRequest();          } catch(e) {} //Native Javascript
   alert("XMLHttpRequest not supported");
   return null;
};

function dochange(src, prod, series) {
     var req = Inint_AJAX();
     req.onreadystatechange = function () { 
          if (req.readyState==4) {
               if (req.status==200) {
                    document.getElementById(src).innerHTML=req.responseText; //รับค่ากลับมา
               } 
          }
     };
     req.open("GET", "ajax/dropdowns.asp?target="+src+"&aprod="+prod+"&aseries="+series); //สร้าง connection
     req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=tis-620"); // set Header
     req.send(null); //ส่งค่า
}

// window.onLoad=dochange('main', 2, 0);
// now loaded via session code in dropdowns.asp, inc_mod_jobsearch_ajax.asp, ajax.js, code on EVERY asp webpage aross the site