lecture-16

Backend 3 | Understand Express Middleware

• Middleware
• Project Structure
• Project

Middleware

• What is Middleware?

• Middleware is just a controller function. It comes from DRY (Don't repeat yourself) principle. It actually used to reuse the controller.

    Req -> M1 -> M2 -> M3 -> Res
  
    ```js
    // We will never call it, express will automatically invoke for us.
    // This is middleware
    function xyz(req, res, next) {
        next();
    }
  
    // This is controller
    function xyz(req, res, next) {
        res.send();
    }
    ```
  

• The basic difference between a middleware and controller is, middleware calls next() function and a controller calls function related to response

• HTTP status code

• .gitignore

Task

• Watch the video and create the structure as shown in video. Write and article with explanation of the structure.