// add Event Listener
function addEvent(eventtype, callfunction)
{
  if (window.addEventListener) {
    window.addEventListener(eventType, callfunction, false);
    return true;
  } else if (window.attachEvent) {
    var returnvalue = window.attachEvent("on" + eventType, callfunction);
    return returnvalue;
  } else {
    return false;
  }
}

// Redirect to URL
function redirect(url) {
  if (url) {
    document.location = url;
  }
  return false;
}