Why middleware is fundamental in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a middleware function that logs every request.

Node.js

app.use(function(req, res, next) { console.log(req.[1]); next(); });

Drag options to blanks, or click blank then click option'

Aurl

Bmethod

Cbody

Dheaders

Attempts:

3 left

💡 Hint

Common Mistakes

Using req.method logs the HTTP method, not the URL.

The middleware logs the URL of each request using req.url.

2fill in blank

medium

Complete the code to create middleware that ends the response with 'Hello World'.

Node.js

app.use(function(req, res, [1]) { res.send('Hello World'); });

Drag options to blanks, or click blank then click option'

Aclose

Bend

Cfinish

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'end' or 'finish' instead of 'next' causes errors.

The middleware function uses next as the third parameter to pass control if needed.

3fill in blank

hard

Fix the error in the middleware that should call the next function.

Node.js

app.use(function(req, res, next) { console.log('Request received'); [1](); });

Drag options to blanks, or click blank then click option'

Ares.send

Bnext

Creq.next

Dres.end

Attempts:

3 left

💡 Hint

Common Mistakes

Calling res.end() or res.send() instead of next() stops middleware chain.

The middleware must call next() to pass control to the next middleware.

4fill in blank

hard

Fill both blanks to create middleware that checks if user is authenticated and calls next if true.

Node.js

app.use(function(req, res, next) { if (req.[1]) { [2](); } else { res.status(401).send('Unauthorized'); } });

Drag options to blanks, or click blank then click option'

AisAuthenticated

Bnext

Csend

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Calling res.send() instead of next() stops the chain.

The middleware checks req.isAuthenticated and calls next() if true.

5fill in blank

hard

Fill all three blanks to create middleware that logs method, URL, and then calls next.

Node.js

app.use(function(req, res, next) { console.log(req.[1] + ' ' + req.[2]); [3](); });

Drag options to blanks, or click blank then click option'

Amethod

Burl

Cnext

Dbody

Attempts:

3 left

💡 Hint

Common Mistakes

Logging req.body instead of req.url or forgetting to call next().

The middleware logs the HTTP method and URL, then calls next() to continue.