CommentButton.jsx

const CommentButton = () => {
  const { data: user } = useUser();
  return (
    <button onClick={user?.id ? user.submitComment : () => { /* 導到登入頁面 */ }}>
      送出留言
    </button>
  );
};

Header.jsx

const Header = () => {
  const { data: user } = useUser();
  return (
    <div>
      { `${user?.name || '遊客'}您好！` }
    </div>
  );
};