MEAN Express.js Middleware and Routing 2

Question 1

What does the `express.static()` middleware do?

Accepted Answer

Serves static files like HTML, CSS, and images from a directory

Answer

express.static() is built-in middleware that serves files from a specified directory, handling file streaming, ETags, and cache headers automatically.

Question 2

How do you set the HTTP status code of a response in Express.js?

Accepted Answer

res.status(404).send('Not Found')

Answer

res.status() sets the HTTP status code and returns the response object for chaining with send(), json(), or end().

Question 3

What is CORS and how is it commonly handled in an Express API?

Accepted Answer

Cross-Origin Resource Sharing, handled with the cors npm middleware package

Answer

CORS allows or restricts web applications from making requests to a different domain; the cors npm package adds the required HTTP headers automatically.

Question 4

Which Express.js method sends a JSON response with the correct Content-Type header?

Accepted Answer

res.json()

Answer

res.json() serializes the passed object to JSON, sets Content-Type to application/json, and sends the response in one call.

Question 5

What does `app.use()` do in Express.js when used without a path argument?

Accepted Answer

Mounts middleware that runs for every incoming request

Answer

When app.use() is called without a path, the middleware function is executed for every request to the application regardless of the route.

MEAN - Stack Development Practice Test

MEAN - Stack Development Practice Test

MEAN Express.js Middleware and Routing 2