Status code usage patterns in Node.js - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

HTTP Status Code for Successful Resource Creation

What status code will this Node.js Express handler send when a new user is successfully created?

Node.js

app.post('/users', (req, res) => {
  // Assume user creation logic here
  res.status(201).send({ message: 'User created' });
});

A 200

B 400

C 201

D 500

💡 Hint

201 is the standard status code for resource creation success.

The handler uses res.status(201), which means the server successfully created a new resource. 201 is the standard HTTP status code for this.

❓ Predict Output

intermediate

Status Code for Unauthorized Access

What status code will this Express middleware send if the user is not authenticated?

Node.js

function authMiddleware(req, res, next) {
  if (!req.user) {
    return res.status(401).send('Unauthorized');
  }
  next();
}

A 403

B 401

C 404

D 200

💡 Hint

401 means the user must authenticate first.

The middleware sends status 401 when req.user is missing, indicating the user is not authenticated.

❓ component_behavior

advanced

Correct Status Code for Invalid Input

Which status code should be sent when the client sends invalid data in a POST request?

Node.js

app.post('/submit', (req, res) => {
  if (!req.body.name) {
    res.status(400).send('Name is required');
  } else {
    res.status(200).send('Success');
  }
});

A 400

B 404

C 500

D 201

💡 Hint

400 means the client sent bad data.

400 Bad Request is the correct status code when the client sends invalid or missing data.

❓ Predict Output

advanced

Status Code for Server Error

What status code will this Express error handler send when an unexpected error occurs?

Node.js

app.use((err, req, res, next) => {
  console.error(err);
  res.status(500).send('Internal Server Error');
});

A 500

B 404

C 400

D 200

💡 Hint

500 means the server failed unexpectedly.

The error handler sends status 500 to indicate an internal server error.

❓ component_behavior

expert

Correct Status Code for Not Found

Which option correctly sends the status code for a 'Not Found' resource?

Node.js

app.get('/item/:id', (req, res) => {
  const item = database.find(req.params.id);
  if (!item) {
    res.status(404).send('Item not found');
  } else {
    res.status(200).json(item);
  }
});

A res.status(400).send('Item not found');

B res.status(200).send('Item not found');

C res.status(500).send('Item not found');

D res.status(404).send('Item not found');

💡 Hint

404 means resource not found.

Only option D correctly uses 404 for a missing resource. Other options send wrong status codes.