if( typeof XMLHttpRequest == "undefined" ) XMLHttpRequest = function() {
  try { return new ActiveXObject("Msxml2.XMLHTTP.6.0") } catch(e) {}
  try { return new ActiveXObject("Msxml2.XMLHTTP.3.0") } catch(e) {}
  try { return new ActiveXObject("Msxml2.XMLHTTP") } catch(e) {}
  try { return new ActiveXObject("Microsoft.XMLHTTP") } catch(e) {}
  throw new Error( "This browser does not support XMLHttpRequest." )
};


function ajax(url, vars, callbackFunction) {
  var asynch = (typeof callbackFunction=='function');
  if(typeof vars=='undefined') vars = null;

  var request =  new XMLHttpRequest();
  request.open("POST", url, asynch);
  request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

  if(asynch){
    request.onreadystatechange = function() {
      if (request.readyState == 4 && request.status == 200) {
        if (request.responseText) {
          callbackFunction(request);
        }
      }
    };
  }
  request.send(vars);
  return request;
}