How to handle 401 error status code error in Node.js/Express?

Question

I am working on login functionality in my project, now, flow looks like this (from front-end to back-end):

async login() {
  await login({
    password: this.userPassword,
    login: this.userLogin,
    twoFactor: this.twoFactor
  }).then((res) => {
    if (res.error) {
      //
    } else {
      console.log(res)
    }
  })
}

And here is starts problems, as you can see if something goes wrong, I return status code 401 and some error message. When I login with correct data, there is no problem with getting token, but when I provide wrong data I have external pending login endpoint in development tools in browser and then, after some time, Error: Request failed with status code 401 in front end terminal. Without this status(401) with just JSON it works fine, but when I try to add 401 code, application crashes.

const userService = require('./../services/userService')
const crypto = require('./../services/cryptoService')
const jwt = require('./../services/jwtService')
const twoFactorService = require('node-2fa')

module.exports = {
  login: async (req, res) => {
    let { login, password, twoFactor } = req.body

    password = crypto.encrypt(password, process.env.APP_KEY)
    const result = await userService.getUserToLogin(login, password)

    if (!result) {
      res.status(401).json({
        error: 'Unauthorized'
      })
    } else {
      const faCode = result.twofatoken
      const result2F = twoFactorService.verifyToken(faCode, twoFactor);
      if ( !result2F || result2F.delta !== 0 ) {
        res.status(401).json({
          error: 'Unauthorized'
        })
      } else {
        const userId = crypto.encrypt(result.id, process.env.CRYPTO_KEY)
        const token = await jwt.sign({
          uxd: userId,
        });
        res.json(token);
      }
    }
  }
}

Actually, I have no idea on what to do with that and how to handle this error.

Answer 1

Ok, here is the answer. Actually, you just need to handle this error in your router:

router.post('/login', async (req, res) => {
  try {
    const data = await api.post('/login', req.body)
    res.json(data.data)
  } catch (e) {
    // Probably you have here just console.log(e), but this way, you can handle it
    res.status(e.response.status).json(e.response.data)
  }
})