MEAN Express.js Middleware and Routing 3

Question 1

What is the purpose of the `helmet` middleware in an Express application?

Accepted Answer

Sets security-related HTTP response headers to protect against common attacks

Answer

Compresses HTTP responses for faster delivery

Answer

Manages session cookies securely

Answer

Validates request headers against a schema

Question 2

Which Express method is used to redirect a client to a different URL?

Accepted Answer

res.redirect()

Answer

res.forward()

Answer

res.navigate()

Answer

res.location()

Question 3

What is rate limiting in Express and which package is commonly used?

Accepted Answer

Limiting requests per time window using express-rate-limit to prevent abuse

Answer

Limiting response payload size using body-parser limits

Answer

Throttling database queries using mongoose middleware

Answer

Capping WebSocket connections using socket.io

Question 4

In Express.js, what is the difference between `app.get()` and `app.use()` for the same path?

Accepted Answer

app.get() only matches exact GET requests; app.use() matches all methods and also sub-paths

Answer

app.get() matches all methods; app.use() only matches GET

Answer

Both are identical in behavior

Answer

app.use() requires an exact path match; app.get() matches sub-paths

Question 5

How do you handle 404 errors for unmatched routes in Express.js?

Accepted Answer

Add a middleware with app.use() after all routes that sends a 404 response

Answer

Set app.notFound() handler during initialization

Answer

Configure 404 in the Express constructor options

Answer

Use app.error(404, handler)

Question 6

What does `res.locals` provide in Express.js?

Accepted Answer

An object for passing data from middleware to route handlers within a single request

Answer

Local configuration settings for the response

Answer

A cache for frequently accessed response data

Answer

Template variables for server-side rendering