Auth using jsonwebtoken(why user is equal to req.user)

Question

here is the code for auth using jsonwebtoken which i got from youtube tutorial, why req.user =user

import jwt from "jsonwebtoken";
const auth = (req, res, next) => {
  try {
    const token = req.header("Authorization");
    if (!token) return res.status(400).json({ msg: "Invalid Authentication" });
    jwt.verify(token, process.env.SECRET_JWT, (err, user) => {
      if (err) return res.status(400).json({ msg: "Authentication Failed" });
      req.user = user;
      next();
    });

Answer 1

You set req.user = user so that you can actually use this in a later middleware function called after this one (triggered by next(). If you do not do something similar to this, you would not know who the user is in the next middleware function or you would have to verify/decode the token every time you need to know who the user is.