Status code conventions in Express - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding HTTP status codes in Express

Which HTTP status code should you use in Express when a client sends a request with missing required data?

A 404 Not Found

B 200 OK

C 400 Bad Request

D 500 Internal Server Error

💡 Hint

Think about what status code means the client made a bad request.

400 Bad Request means the server cannot process the request due to client error, such as missing data.

❓ component_behavior

intermediate

Express response status for successful resource creation

What status code does Express typically send when a new resource is successfully created?

A 201 Created

B 202 Accepted

C 204 No Content

D 200 OK

💡 Hint

This code means the server created something new.

201 Created indicates that the request was successful and a new resource was created.

📝 Syntax

advanced

Correct usage of status codes in Express response

Which Express code snippet correctly sends a 404 status with a JSON error message?

A res.json(404, { error: 'Not found' });

B res.status(404).json({ error: 'Not found' });

C res.status(404).send({ error: 'Not found' });

D res.sendStatus(404).json({ error: 'Not found' });

💡 Hint

Check the chaining and method usage for setting status and sending JSON.

res.status(404).json(...) sets the status code and sends JSON correctly.

❓ state_output

advanced

Output status code for unauthorized access in Express

What status code will Express send if you use res.status(401).send('Unauthorized')?

Express

app.get('/secret', (req, res) => {
  res.status(401).send('Unauthorized');
});

A 401 Unauthorized with body 'Unauthorized'

B 200 OK with body 'Unauthorized'

C 403 Forbidden with body 'Unauthorized'

D 500 Internal Server Error

💡 Hint

The status code you set is sent as the HTTP response status.

res.status(401) sets the HTTP status to 401 Unauthorized, and send() sends the response body.

🔧 Debug

expert

Identify the error in status code usage

What error occurs when running this Express code snippet?

app.get('/data', (req, res) => {
  res.status(201).send('Created');
  res.status(200).send('OK');
});

Express

app.get('/data', (req, res) => {
  res.status(201).send('Created');
  res.status(200).send('OK');
});

A No error, sends 201 Created

B SyntaxError: Unexpected token

C No error, sends 200 OK

D Error: Cannot set headers after they are sent to the client

💡 Hint

Think about sending multiple responses in one request.

Express throws an error if you try to send more than one response for a single request.