function createXMLHttpRequest() {



var aa;

if(window.XMLHttpRequest) {
    try {
      aa = new XMLHttpRequest();
    } catch(e) {
      aa = false;
    }
  } else if(window.ActiveXObject) {
    try {
      aa = new ActiveXObject("Microsoft.XMLHTTP");
    } catch(e) {
      aa = false;
    }
  }
  return aa;
}

var req = createXMLHttpRequest();