Q4: What is Middleware in Express.js and what is its role?
A middleware function is a callback that has access to the request object (req), response object (res), and the next callback function in the application's request-response cycle.
Responsibilities of Middleware
- Execute arbitrary execution logic.
- Make modifications to
reqandresobjects. - End the request-response cycle by sending a response.
- Pass execution control to the next middleware by invoking
next().
Express Middleware Execution Chain
Key Takeaways
- Express is essentially a series of middleware function calls executed sequentially.
- Failing to call
next()or send a response leaves the request hanging indefinitely.