Application-level middleware in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an application-level middleware that logs every request method.

Express

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.url instead of req.method

Trying to log req.body which may not exist yet

Forgetting to call next() to continue middleware chain

The req.method property contains the HTTP method of the request, such as GET or POST. Logging it helps track request types.

2fill in blank

medium

Complete the code to add a middleware that sets a custom header 'X-App-Version' with value '1.0'.

Express

app.use(function(req, res, next) {
  res.setHeader('[1]', '1.0');
  next();
});

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

AAuthorization

BContent-Type

CX-App-Version

DAccept

Attempts:

3 left

💡 Hint

Common Mistakes

Using standard headers like Content-Type instead of the custom one

Misspelling the header name

Not calling next() to continue middleware

The header X-App-Version is a custom header used to indicate the app version. Setting it on the response helps clients know the version.

3fill in blank

hard

Fix the error in the middleware that tries to parse JSON body but is missing a function call.

Express

app.use(express.[1]());

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

Ajson

Burlencoded

Crouter

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Using express.json without parentheses

Using express.urlencoded for JSON data

Using express.static which serves files

The express.json() middleware parses incoming JSON requests. It must be called as a function to return the middleware.

4fill in blank

hard

Fill both blanks to create middleware that logs the request URL and then calls next.

Express

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

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

Anext

Bmethod

Curl

Dres

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'res' instead of 'next' as third parameter

Logging req.method instead of req.url

Forgetting to call next()

The third parameter in middleware is next, which you call to continue. The request URL is accessed via req.url.

5fill in blank

hard

Fill all three blanks to create middleware that checks if a user is authenticated and calls next or sends 401.

Express

app.use(function(req, res, next) {
  if (req.[1] && req.[2].isAuthenticated()) {
    [3]();
  } else {
    res.status(401).send('Unauthorized');
  }
});

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

Auser

Bsession

Cnext

Dbody

Attempts:

3 left

💡 Hint

Common Mistakes

Checking req.session instead of req.user

Calling next without parentheses

Not sending 401 status on failure

The req.user object holds user info. Calling req.user.isAuthenticated() checks if logged in. If yes, call next() to continue.