Familiarize Yourself with Middleware Functions

Before moving to implementation, we need to understand middleware functions. Our API rate-limiting function is actually going to be a middleware function that can be reused in any of the API routes, with a configurable window and the maximum number of API calls allowed per IP address in that window.

What are middleware functions?

In Express.js, middlewares are functions that have access to the request (req) and response (res) objects in the application's request-response cycle. They can perform various tasks, such as modifying request or response objects, executing code before or after the request is handled, or terminating the request-response cycle. Middleware can be used to:

• Execute code before the request is processed by the route handlers.

• Modify the request or response objects by adding or modifying properties. ...