res.status for status codes in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the HTTP status to 404.

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

D302

Attempts:

3 left

💡 Hint

Common Mistakes

Using 200 which means OK instead of 404.

Using 500 which means server error.

Using 302 which means redirect.

The res.status() method sets the HTTP status code. 404 means 'Not Found'.

2fill in blank

medium

Complete the code to send a 201 status code after creating a resource.

Express

app.post('/create', (req, res) => {
  // resource creation logic
  res.status([1]).send('Created');
});

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

A404

B400

C201

D500

Attempts:

3 left

💡 Hint

Common Mistakes

Using 400 which means bad request.

Using 404 which means not found.

Using 500 which means server error.

201 means 'Created' and is used after successfully creating a resource.

3fill in blank

hard

Fix the error in setting the status code to 500 for server error.

Express

app.get('/error', (req, res) => {
  res.status([1]).send('Server error occurred');
});

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

A'500'

B500

Cstatus(500)

Dres.status(500)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the status code as a string like '500'.

Calling status(500) inside the argument.

Passing res.status(500) inside the argument.

The res.status() method expects a number, not a string or a function call inside.

4fill in blank

hard

Fill both blanks to set status 403 and send a message 'Forbidden'.

Express

app.get('/forbidden', (req, res) => {
  res.status([1]).[2]('Forbidden');
});

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

A403

Bsend

Cjson

D404

Attempts:

3 left

💡 Hint

Common Mistakes

Using 404 instead of 403 for forbidden.

Using json instead of send when sending plain text.

403 is the status code for 'Forbidden'. The send method sends the response body as text.

5fill in blank

hard

Fill all three blanks to set status 302, redirect to '/login', and end the response.

Express

app.get('/redirect', (req, res) => {
  res.status([1]).[2]('/login').[3]();
});

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

A404

Bredirect

Cend

D302

Attempts:

3 left

💡 Hint

Common Mistakes

Using 404 instead of 302 for redirect.

Using send instead of redirect.

302 is the status code for redirect. redirect sends the redirect response. end ends the response process.

Practice

1. What does res.status(404) do in an Express route handler?

easy

A. Changes the request method to GET

B. Sends a 404 error message to the client automatically

C. Sets the HTTP response status code to 404 (Not Found)

D. Stops the server from running

Solution

1. Step 1: Understand the purpose of res.status

   res.status(code) sets the HTTP status code for the response but does not send the response itself.

2. Step 2: Identify what 404 means

   404 is the standard HTTP status code meaning "Not Found".

3. Final Answer:

   Sets the HTTP response status code to 404 (Not Found) -> Option C

4. Quick Check:

   res.status(404) = sets status code 404 [OK]

Hint: res.status sets code; use res.send or res.json to send [OK]

Common Mistakes:

• Thinking res.status sends the response automatically
• Confusing status code with request method
• Assuming res.status stops server execution

2. Which of the following is the correct way to send a 201 status with a JSON response in Express?

easy

A. res.status.json(201, { message: 'Created' })

B. res.send(201).json({ message: 'Created' })

C. res.json(201, { message: 'Created' })

D. res.status(201).json({ message: 'Created' })

Solution

1. Step 1: Recall correct chaining syntax

   In Express, res.status(code) sets the status code, then res.json(data) sends the JSON response.

2. Step 2: Check each option's syntax

   res.status(201).json({ message: 'Created' }) correctly chains res.status(201) with res.json({ message: 'Created' }). Others misuse method order or parameters.

3. Final Answer:

   res.status(201).json({ message: 'Created' }) -> Option D

4. Quick Check:

   Correct chaining = res.status().json() [OK]

Hint: Use res.status(code).json(data) to set code and send JSON [OK]

Common Mistakes:

• Calling res.send before res.status
• Passing status code as first argument to res.json
• Using res.status.json which is invalid

3. What will the client receive when this Express handler runs?

app.get('/test', (req, res) => {
  res.status(500);
  res.send('Server error');
});

medium

A. A response with status 200 and body 'Server error'

B. A response with status 500 and body 'Server error'

C. A response with status 500 and empty body

D. An error thrown by Express

Solution

1. Step 1: Analyze res.status and res.send usage

   res.status(500) sets the HTTP status code to 500. Then res.send('Server error') sends the response body with that status.

2. Step 2: Determine final response

   The client receives status 500 with the text 'Server error' as the body.

3. Final Answer:

   A response with status 500 and body 'Server error' -> Option B

4. Quick Check:

   res.status(500) + res.send('Server error') = 500 + body [OK]

Hint: res.status sets code; res.send sends body with that code [OK]

Common Mistakes:

• Assuming res.send resets status to 200
• Thinking status 500 causes Express error automatically
• Believing response body is empty without res.send argument

4. Identify the error in this Express code snippet:

app.get('/error', (req, res) => {
  res.send('Oops!');
  res.status(400);
});

medium

A. res.status(400) is called after res.send, so status code is ignored

B. res.send cannot be called without res.status first

C. res.status must be called with a string, not a number

D. No error, this code works correctly

Solution

1. Step 1: Understand response flow in Express

   Once res.send() is called, the response is sent and closed. Any code after it won't affect the response.

2. Step 2: Analyze order of calls

   Here, res.send('Oops!') sends the response with default status 200. Then res.status(400) is called but ignored because response is already sent.

3. Final Answer:

   res.status(400) is called after res.send, so status code is ignored -> Option A

4. Quick Check:

   Call res.status before res.send to set status [OK]

Hint: Always call res.status before res.send or res.json [OK]

Common Mistakes:

• Calling res.status after res.send expecting status change
• Thinking res.send requires res.status first
• Using string instead of number in res.status

5. You want to send a 204 No Content status with no response body in Express. Which code snippet correctly does this?

hard

A. res.status(204).send()

B. All of the above

C. res.status(204).json(null)

D. res.sendStatus(204)

Solution

1. Step 1: Understand 204 No Content meaning

   Status 204 means the server successfully processed the request but returns no content in the response body (Content-Length: 0).

2. Step 2: Check each option's behavior

   res.status(204).send() sends status 204 with empty body [check].
   res.status(204).json(null) sends status 204 with JSON "null" body ✗.
   res.sendStatus(204) sends status 204 with "No Content" text body ✗.
   Only A sends no response body.

3. Final Answer:

   res.status(204).send() -> Option A

4. Quick Check:

   res.status(204).send() = 204 + empty body [OK]

Hint: Use res.status(204).send() for 204 with no body [OK]

Common Mistakes:

• Sending body content with 204 status (should be empty)
• Using res.status(204).json({}) which sends empty object body
• Not sending response after setting status