[Solved] Identify the error in this functional middleware code: function check(req, res, next) { if (!req.user) { res.status(401).send('Unauthorized'); } next(); } | NestJS

NestJS - Middleware

Identify the error in this functional middleware code:

function check(req, res, next) {
  if (!req.user) {
    res.status(401).send('Unauthorized');
  }
  next();
}

AMissing req, res parameters

Bnext() is called even after sending a response

Cres.status should be res.sendStatus

DMiddleware must be a class

Step-by-Step Solution

Solution:

Step 1: Check response flow
If req.user is missing, the middleware sends a 401 response.
Step 2: Analyze next() call
Calling next() after sending a response causes the next middleware or handler to run unnecessarily.
Final Answer:
next() is called even after sending a response -> Option B
Quick Check:
Do not call next() after sending response [OK]

Quick Trick: Return or skip next() after sending response [OK]

Common Mistakes:

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