react笔记

Hook 只能在组件函数的顶层调用

错误示范如下：

if (isSent) {

    return <h1>Thank you!</h1>;

  } else {

    // eslint-disable-next-line

    const [message, setMessage] = useState('');

}

正确示范：

const [isSent, setIsSent] = useState(false);

const [message, setMessage] = useState('');

  if (isSent) {

    return <h1>Thank you!</h1>;

  } else {

}