Creating Custom Middleware

You can create your own middleware to control how requests are processed.

A middleware function receives three arguments: req, res, and next.

const logger = (req, res, next) => {
  console.log(req.method, req.url);
  next();
};

app.use(logger);

This middleware logs the request method and URL for every incoming request.

When a request comes in:

• Middleware runs first;
• It performs its logic;
• It calls next() to continue.

If next() is not called, the request will not move forward.

Custom middleware is useful for adding shared behavior across your application, such as logging or validation.