Authentication example 41

What this example teaches

Authentication

Output

The endpoint responds with JSON that a frontend or mobile app can use.

Line-by-line explanation

• Line 1 sets up the Authentication example: function requireUser(req, res, next) {.
• Line 2 adds the decision or filter that controls the result: if (!req.headers.authorization) return res.status(401).json({ error: "Login required" });.
• Line 3 adds one required part of the working pattern: next();.
• Line 4 adds one required part of the working pattern: }.

Why this example is useful

This example is useful because it isolates authentication without surrounding noise, so you can see the idea clearly.

Where it is used in real projects

Authentication appears in real NodeJS work when a feature needs a clear pattern that can be reviewed and changed safely.

Beginner variation

Change one label, value or condition in the Authentication example and run it again.

Advanced variation

Combine Authentication with validation, error handling or reusable structure.