Node.js Express.js & REST APIs 3

Question 1

What does res.status(404).json({ error: 'Not found' }) do differently than res.json({ error: 'Not found' })?

Accepted Answer

It sets the HTTP status code to 404 before sending JSON

Answer

res.status() sets the HTTP status code, and json() then sends the response body with that code.

Question 2

In Express route definition app.get('/users/:id', handler), how do you access the dynamic segment?

Accepted Answer

req.params.id

Answer

Named route segments prefixed with : are available on the req.params object.

Question 3

Which HTTP method is idempotent AND safe according to REST conventions?

Accepted Answer

GET

Answer

GET is both safe (no side effects) and idempotent (repeated calls yield the same result).

Question 4

What is the correct signature for an Express error-handling middleware?

Accepted Answer

(err, req, res, next) => {}

Answer

Express identifies error-handling middleware by its four-parameter signature: err, req, res, next.

Question 5

When you call app.use('/api', router) where router has router.get('/users', fn), what full path triggers fn?

Accepted Answer

/api/users

Answer

Express concatenates the mount path /api with the router's /users path to form /api/users.

Node.js Practice Test