var xhr;

      function showDateAndTime() {
          sendRequest("dateAndTime.ajax", // the URL
                      processAjaxCall);   // the callback function
      }

      function sendRequest(url, handler) {
         initXHR();
         xhr.onreadystatechange = handler; // set callback function
         xhr.open("GET", url, true); // open asynchronous GET request
         xhr.send(null); // send the request without params
      }

      function initXHR() {
         if(window.XMLHttpRequest) {
            xhr = new XMLHttpRequest();
         }
         else if(window.ActiveXObject) {
            xhr = new ActiveXObject("Microsoft.XMLHTTP");
         }
      }

      function processAjaxCall() {
         if(xhr.readyState == 4) {  // if the request is finished...
            if(xhr.status == 200) { // ...and everything's okay
               // Get the dateDiv DIV and configure it
               // with the response text
              var dateDiv = window.document.getElementById("dateDIV");
              dateDiv.innerHTML = xhr.responseText;
            }
         }
      }