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JavaScript User Authentication With Express and Mongo User Registration Adding Data to the Database

Charles-Antoine Francisco
Charles-Antoine Francisco
27,426 Points

Why is the Sign Up Form Validation done on the server?

In the code for the POST /register route, we check that all form fields (email, name, favoriteBook, password, confirmPassword) are entered and that the password and confirmPassword fields match.

I think this could be done on the frontend part of the app and avoid a network call to the server.

// POST /register
router.post('/register', function(req, res, next) {
  if (req.body.email && req.body.name && req.body.favoriteBook &&
    req.body.password && req.body.confirmPassword) {
      // confirm that user typed same password twice
      if (req.body.password !== req.body.confirmPassword) {
        var err = new Error('Passwords do not match.');
        err.status = 400;
        return next(err);
      }
      // insert document into Mongo...
    } else {
      var err = new Error('All fields required.');
      err.status = 400;
      return next(err);
    }
})

1 Answer

Steven Parker
Steven Parker
229,788 Points

Validation should always be done on the server.

Ideally, it would also be done on the front end, to avoid transmitting known bad data to the server. But it should still be done at the server to catch any possible errors caused by unexpected browser behavior or front-end tampering.

Charles-Antoine Francisco
Charles-Antoine Francisco
27,426 Points

Thanks, that clarifies things. I didn't think about users who could modify the frontend code. Good points.