CommentButton.jsx

const CommentButton = () => {
  const { data: user } = useUser();
  return (
    <button onClick={user.submitComment}>
      送出留言
    </button>
  );
};

Header.jsx

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