Error response formatting in Express - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to send a JSON error response with status 404.

Express

app.get('/item/:id', (req, res) => {
  const item = database.find(i => i.id === req.params.id);
  if (!item) {
    return res.status([1]).json({ error: 'Item not found' });
  }
  res.json(item);
});

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

A200

B500

C404

D400

Attempts:

3 left

💡 Hint

Common Mistakes

Using status 200 for errors

Using status 500 for client errors

Use status code 404 to indicate the requested item was not found.

2fill in blank

medium

Complete the code to send a JSON error response with a custom message and status 400.

Express

app.post('/user', (req, res) => {
  if (!req.body.name) {
    return res.status([1]).json({ error: 'Name is required' });
  }
  res.json({ success: true });
});

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

A401

B404

C403

D400

Attempts:

3 left

💡 Hint

Common Mistakes

Using 401 which means unauthorized

Using 404 which means not found

Status 400 means 'Bad Request', suitable when required data is missing.

3fill in blank

hard

Fix the error in the code to correctly send a JSON error response with status 500.

Express

app.get('/data', (req, res) => {
  try {
    const data = getData();
    res.json(data);
  } catch (error) {
    res.status([1]).json({ error: error.message });
  }
});

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

A500

B400

C404

D200

Attempts:

3 left

💡 Hint

Common Mistakes

Using res.send instead of res.json for JSON response

Using wrong status codes like 200 or 404

Use status 500 for server errors and send JSON with res.status(500).json(...).

4fill in blank

hard

Fill both blanks to send a JSON error response with status 401 and a message.

Express

app.use((req, res) => {
  res.status([1]).json({
    error: [2]
  });
});

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

A401

B'Unauthorized access'

C'Not Found'

D403

Attempts:

3 left

💡 Hint

Common Mistakes

Using status 403 which means forbidden

Using error message 'Not Found' for unauthorized

Status 401 means unauthorized. The error message should explain the issue.

5fill in blank

hard

Fill all three blanks to send a JSON error response with status 403 and a detailed message.

Express

app.get('/admin', (req, res) => {
  if (!req.user || !req.user.isAdmin) {
    return res.status([1]).json({
      error: [2],
      message: [3]
    });
  }
  res.json({ secret: '42' });
});

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

A401

B'Forbidden'

C'You do not have permission to access this resource.'

D403

Attempts:

3 left

💡 Hint

Common Mistakes

Using 401 instead of 403 for forbidden

Using vague or missing error messages

Status 403 means forbidden. The error and message explain the access denial.