TypeScript async/await最佳实践：Express代码冗余写法疑问

我在ExpressJS中使用TypeScript开发密码找回功能，编写了如下精简代码，现在有个疑问：执行const results = await checkForEmailAddress(email);时，调用async函数前使用了await，而该函数内部也采用了async/await写法，想确认这种做法是否符合最佳实践，是否存在冗余。

/**
 * Verifies that an email address exists in the DB.
 * If so, sends them an email to recover their password.
 * 
 * @param {Request} req 
 * @param {Response} res 
 */
const sendPasswordRecoveryEmail = (req: Request, res: Response) => {
  const email = req.body.email

  const checkForEmailAddress = async (email: string) => {
    return await pool.query(`SELECT password FROM users WHERE email = $1`, [email]);
  };

  const updatePasswordFields = async (password: string, newPassword: string, email: string) => {
    return await pool.query(`UPDATE users SET last_password = $1, password = $2 WHERE email = $3`, [password, newPassword, email]);
  };

  const passwordRecoveryProcess = async (email: string) => {
    try {
      res.status(200).send({ status: true, message: 'Password recovery process initiated.' });

      const results = await checkForEmailAddress(email);
      if (results.rows.length === 1) {
        const existingPassword = results.rows[0].password;
        const newTempPassword = generateRandomPassword();
        await updatePasswordFields(existingPassword, newTempPassword, email);
        const body = `...`;
        emailService({email, subject: 'MySite Password Recovery', body});
      }
    } catch (error) {
      console.error('Error', error);
    }
  }

  passwordRecoveryProcess(email); // Initiate async Password Recovery Process
};

回答 #

这种写法符合最佳实践，不存在功能上的冗余，具体解释如下：

• 外层调用checkForEmailAddress时使用await是必要的：因为checkForEmailAddress是async函数，返回的是一个Promise，只有用await才能等待这个Promise完成，拿到实际的数据库查询结果，否则后续判断results.rows.length会因为拿到Pending状态的Promise而报错。
• 内部函数里的await本身是合理的：pool.query是异步操作，返回Promise，内部用await是为了等待数据库操作完成，确保函数返回的是查询结果的Promise。不过这里可以做简洁化优化：因为pool.query已经返回Promise，async函数会自动将返回值包装为Promise，所以可以去掉内部的await，直接返回pool.query的结果，效果完全一致，比如：

  const checkForEmailAddress = async (email: string) => {
    return pool.query(`SELECT password FROM users WHERE email = $1`, [email]);
  };
  

  甚至可以去掉async关键字，直接返回Promise：

  const checkForEmailAddress = (email: string) => {
    return pool.query(`SELECT password FROM users WHERE email = $1`, [email]);
  };
  

  这两种优化写法和原代码功能完全相同，但更简洁。原代码的写法虽然多了一层await包装，但不会影响功能和性能，只是略显冗余，并非错误写法。

内容的提问来源于stack exchange，提问作者RobertW