// This function performs AJAX calls.
// Target must be the ID of the HTML to update (uses innerHTML)
// For sending data to the server, set the target as false.
function AJAX(url,data,target){
  // Create xmlHttp object for AJAX calls
  var xmlHttp;
  if (window.XMLHttpRequest){
    xmlHttp = new XMLHttpRequest();
  } else if (window.ActiveXObject){
    xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
  }
  xmlHttp.onreadystatechange = function(){
    if(xmlHttp.readyState == 4 && xmlHttp.status == 200 && target != false){
      if(document.getElementById(target).tagName.toLowerCase() == 'textarea'){
        document.getElementById(target).value = xmlHttp.responseText;
      } else {
        document.getElementById(target).innerHTML = xmlHttp.responseText;
      }
    }  
  } 
  xmlHttp.open("POST",url,true);
  xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  xmlHttp.setRequestHeader("Content-length", data.length);
  xmlHttp.setRequestHeader("Connection", "close");
  xmlHttp.send(data);   
}

// This function handles AJAX errors gracefully.
function ajaxError(e){
  return false;
}

// Main function for retrieving data using AJAX functions above
// Target must be the ID of the element to update.
function getData(parameters,target){
  var url = "ajax";
  var data = parameters + "&nocache=" + Math.random();
  try{
    var response = AJAX(url,data,target);  
  } catch(e) {
    return ajaxError(e);
  }
}