function checkSession() {
  if (userSession) {
    xajax_checkSession(userSession.session, userSession.id);
  }

}

function multipleLogins() {
  location.href = "/multiple-logons.php";
}

function keepChecking() {
  window.setTimeout(checkSession, 30000);
}


if (checkSessions) {
  keepChecking();
}