Middleware composition for auth layers in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Express

app.use([1]);

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

AloggerMiddleware

Bexpress.json()

Ccors()

DbodyParser.urlencoded()

Attempts:

3 left

💡 Hint

Common Mistakes

Using middleware that parses JSON instead of logging.

Forgetting to pass a function to app.use.

The app.use() method adds middleware. Here, loggerMiddleware is the function that logs requests.

2fill in blank

medium

Complete the code to protect a route with authentication middleware.

Express

app.get('/dashboard', [1], (req, res) => { res.send('Welcome!'); });

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

AloggerMiddleware

Bcors()

CauthMiddleware

Dexpress.static('public')

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated middleware like logger or cors for authentication.

Placing middleware after the route handler.

The authMiddleware checks if the user is authenticated before allowing access to the dashboard route.

3fill in blank

hard

Fix the error in composing two middleware functions for a route.

Express

app.post('/submit', [1], (req, res) => { res.send('Submitted'); });

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

AauthMiddleware || loggerMiddleware

BauthMiddleware, loggerMiddleware

CauthMiddleware && loggerMiddleware

D[authMiddleware, loggerMiddleware]

Attempts:

3 left

💡 Hint

Common Mistakes

Using logical operators instead of array or separate arguments.

Passing middleware as a comma-separated string.

To use multiple middleware functions for a route, pass them as an array or as separate arguments. Here, an array is correct syntax inside the single blank.

4fill in blank

hard

Fill both blanks to create a middleware chain that first authenticates, then logs the request.

Express

app.use([1], [2]);

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

AauthMiddleware

BloggerMiddleware

Cexpress.json()

Dcors()

Attempts:

3 left

💡 Hint

Common Mistakes

Reversing the order of middleware.

Using unrelated middleware like cors or json parser.

The middleware chain runs in order: first authMiddleware to check authentication, then loggerMiddleware to log the request.

5fill in blank

hard

Fill all three blanks to create a route with JSON parsing, authentication, and logging middleware.

Express

app.post('/api/data', [1], [2], [3], (req, res) => { res.json({ success: true }); });

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

Aexpress.json()

BauthMiddleware

CloggerMiddleware

Dcors()

Attempts:

3 left

💡 Hint

Common Mistakes

Wrong order of middleware causing errors.

Using cors middleware instead of logger.

The route uses express.json() to parse JSON body, then authMiddleware to check user, and finally loggerMiddleware to log the request.