var http_request = false;

function request_data(url, callback_function, post_data) {
   http_request = false;

   if(window.XMLHttpRequest) {
      http_request = new XMLHttpRequest();
      if(http_request.overrideMimeType) {
         http_request.overrideMimeType('text/plain');
      }
   }
   else if(window.ActiveXObject) {
      try {
         http_request = new ActiveXObject("Msxml2.XMLHTTP");
      }
      catch (e) {
         try {
            http_request = new ActiveXObject("Microsoft.XMLHTTP");
         }
         catch (e) {

         }
      }
   }

   if(!http_request) {
      alert('Giving up :( Cannot create an XMLHTTP instance');
      return false;
   }

   http_request.onreadystatechange = callback_function;

   if(post_data && post_data.length) {
      http_request.open('POST', url, true);
      http_request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
      http_request.setRequestHeader("Content-length", post_data.length);
      http_request.setRequestHeader("Connection", "close");
      http_request.send(post_data);
   }
   else {

      http_request.open('GET', url, true);
      http_request.send(null);
   }
   return true;
}

function tweak_ui() {
   var post_data = 'year=yyyy&company_age=int';
   request_data('ambush.php', update_ui, post_data);      
}

function update_ui() {
   if(http_request.readyState == 4) {
      if(http_request.status == 200) {
         var obj = eval('(' + http_request.responseText + ')');

         if(document.getElementById("year")) {
            document.getElementById("year").innerHTML = obj["year"];
         }
         if(document.getElementById("company_age")) {
            document.getElementById("company_age").innerHTML = obj["company_age"];
         }         
      }
      else {
         alert('There was a problem with the request.');
      }
   }
}