Why understanding res matters in Express - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a simple text response using Express.

Express

app.get('/', (req, [1]) => {
  [1].send('Hello World!');
});

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

Ares

Bresult

CresponseObj

Drequest

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'request' or 'result' instead of 'res' causes errors.

Trying to send response with 'req' instead of 'res'.

The res object is used to send the response back to the client in Express.

2fill in blank

medium

Complete the code to set the HTTP status code to 404 before sending the response.

Express

app.get('/notfound', (req, res) => {
  res.status([1]).send('Page not found');
});

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

A404

B200

C500

D301

Attempts:

3 left

💡 Hint

Common Mistakes

Using 200 means success, which is incorrect here.

Using 500 means server error, not 'not found'.

HTTP status code 404 means 'Not Found'. Setting it before sending the response tells the client the page was not found.

3fill in blank

hard

Fix the error in the code to properly send a JSON response.

Express

app.get('/data', (req, [1]) => {
  [1].json({ message: 'Hello' });
});

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

Aresponse

Brequest

Cresult

Dres

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different name than 'res' but calling 'res.json()' causes errors.

Swapping the order of parameters.

The callback must use res as the second parameter to call res.json().

4fill in blank

hard

Fill both blanks to set a custom header and send a plain text response.

Express

app.get('/custom', ([1], [2]) => {
  [2].set('X-Custom-Header', '12345');
  [2].send('Custom header set');
});

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

Areq

Bres

Crequest

Dresponse

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of parameters.

Using the wrong variable name for the response object.

The first parameter is the request object (req), the second is the response object (res), which is used to set headers and send responses.

5fill in blank

hard

Fill all three blanks to send a JSON response with status 201 and a custom header.

Express

app.post('/create', ([1], [2]) => {
  [2].status([3]).set('Location', '/new-item').json({ success: true });
});

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

Areq

Bres

C201

D200

Attempts:

3 left

💡 Hint

Common Mistakes

Using status 200 instead of 201 for creation.

Swapping req and res parameters.

The first parameter is req, the second is res. Status code 201 means 'Created'. We set a 'Location' header and send JSON.