JAVASCRIPT

ingore render on refresh page

return (
    <div>
      { loggedIn !== null &&
         <Router>
            ...
         </Router>
      }

    </div>
  );

ingore render on refresh page

const [loggedIn, setLoggedIn] = useState(null);

useEffect(() => {
    const loggedUser = localStorage.getItem('user');
    setLoggedIn(Boolean(loggedUser));
  }, []);