Question

从第一个文件中调用一个函数，然后在第一个函数完成并返回true时执行其他操作的最佳方法是什么？

module.exports = {
  sendEmail: function(user, subject, text) {
    var smtpTransport = nodemailer.createTransport({
      service: 'gmail',
      auth: {
        user: config.email,
        pass: config.gmlpwd
      }
    });
    var mailOptions = {
      to: user,
      from: config.email,
      subject: subject,
      text: text
    };
    smtpTransport.sendMail(mailOptions, function(err) {
      return true
    });
  }
}

mailer.sendEmail(user.email, subject, text, function(){
     //do something here if the function is done successfully, but it never gets called
});

Answer 1

在sendMail函数内部，您需要将该回调添加为参数，然后在完成后调用它。

module.exports = {
  sendEmail: function(user, subject, text, cb) {
    var smtpTransport = nodemailer.createTransport({
      service: 'gmail',
      auth: {
        user: config.email,
        pass: config.gmlpwd
      }
    });
    var mailOptions = {
      to: user,
      from: config.email,
      subject: subject,
      text: text
    };
    smtpTransport.sendMail(mailOptions, function(err) {
      return cb(err);
    });
  }
}

mailer.sendEmail(user.email, subject, text, function(){
     // do something here
});

但是，反复执行此操作可能会导致您进入callback hell，建议您改用Promise或RxJS。

Answer 2

      <!-- With cb -->

      module.exports = {
         sendEmail: function(user, subject, text, callback) {
            var smtpTransport = nodemailer.createTransport({
              service: 'gmail',
              auth: {
                user: config.email,
                pass: config.gmlpwd
              }
            });
            var mailOptions = {
              to: user,
              from: config.email,
              subject: subject,
              text: text
            };
            smtpTransport.sendMail(mailOptions, function(err) {
              if (err) callback({ err })
              callback({ result: "All is ok" })
            });
        }
      }

      // 

    var mailer = require('./file.js');
    mailer.sendMail('go@mail.com', 'Hello world', 'Lorem ipsum dolor sit ammet', function({ err, result}){
      if (err) {
        console.log(err, '- Some error')

      } else {
        console.log(result, 'Some code here')
      }
    })
  <!-- With Async promise -->

  module.exports = {
     sendEmail:  new Promise(function(resolve, reject){
        function(user, subject, text) {
          var smtpTransport = nodemailer.createTransport({
            service: 'gmail',
            auth: {
              user: config.email,
              pass: config.gmlpwd
            }
          });
          var mailOptions = {
            to: user,
            from: config.email,
            subject: subject,
            text: text
          };
          smtpTransport.sendMail(mailOptions, function(err) {
            if (err) reject({ err })
            resolve({ result: 'All is ok result here'})
          });
      }
    }
  }

  // 

var mailer = require('./file.js');
mailer.sendMail('go@mail.com', 'Hello world', 'Lorem ipsum dolor sit ammet').then(function ({ result}) {
  console.log( 'All is ok')
})

Answer 3

在这种情况下，我更喜欢使用async/await，在这种情况下，您只需要将函数与对象一起进行导出即可，让我们看下面的示例。

文件1： userController.js

const userUtils = require('./userUtils');

const userCtr = {};

userCtr.searchUser = async (req, res) => {
  try {
    const { userName } = req.query;
    const result = await userUtils.searchUser(userName);
    return res.status(200).json(result);
  } catch (err) {
    return res.status(err.code).json({ error: err.error });
  }
};

module.exports = userCtr;

文件2： userUtils.js

const userUtils = {};

userUtils.searchUser = async (userName) => {
  try {
    if (userName) {
      // ...Do some cool stuff
      const result = [];
      return result;
    }
    const errorObj = { code: 400, error: 'ERR_VALID_PARAM' };
    throw errorObj;
  } catch (err) {
    console.error(err);
    throw err;
  }
};

module.exports = userUtils;

在上述实例中，我们从searchUser()调用了函数userUtils，如果存在参数，该函数将返回一个空数组，否则将引发错误。这只是您了解module.exports

的简单用例

从另一个文件调用函数并在完成后获取结果？

3 个答案: