Murad-Hasan / express_practice

function handler (req, res, next){

-read request object
-process request
-response back to result

}

Type of request we mainly used: GET, POST, PUT, DELETE, PATCH , HEAD, OPTIONS (we can use more) -----> HTTP method

Request object:

• request
• response
• middleware
• router

Middleware Can Do Something Before Request: --->> middleware one kind of handler <<---

• modify request object (add new property, change property, delete property)
• response back to client from any where in the middleware
• data filtering, data validation, data sanitization, authentication etc.

Middleware Responsibility

• handle common tasks
• request logs
• filter request
• modify or reshape request
• validate request body
• authenticate or authorize request
• add additional details to request body
• response bad request
• pass request to next middleware or response handler

Morgan --> logger middleware

cors --> cross origin resource sharing middleware

Route Specific middleware

app.get("/about", cors(), (req, res) => {} // single middleware
    or,
app.get("/about", [cors(), cors()], (req, res)) => {} // array of middleware

Middleware Signature

                **Controller vs Middleware**

If everything seems ok controller will call response methods .

If everything seems ok middleware will call next() method .

function(req, res, next) {
    //Read request object
    //Process request
    //Response back to result
}

function middlewareSignature (req, res, next) {
    console.log("middlewareSignature");
    next();
  }

router

• router mainly a middleware;

  const router = express.Route();
  app.use(router);