Node.js Express.js & REST APIs

Question 1

What is middleware in Express.js?

Accepted Answer

Functions that have access to the request, response, and next function in the application's request-response cycle

Answer

Express middleware functions execute during the request-response cycle, accessing the request object, response object, and calling next() to pass control to the next middleware.

Question 2

What HTTP method should be used to update an existing resource in a REST API?

Accepted Answer

PUT or PATCH

Answer

PUT replaces the entire resource with the provided data, while PATCH applies partial modifications. Both are appropriate for updating existing resources in RESTful API design.

Question 3

What is the purpose of 'app.use()' in Express.js?

Accepted Answer

To mount middleware functions that will execute for every request matching the specified path

Answer

app.use() mounts middleware functions at a specified path (or all paths if none specified), executing them for every incoming request that matches.

Question 4

What is CORS and how is it handled in Express?

Accepted Answer

Cross-Origin Resource Sharing — a security mechanism configured via the 'cors' middleware package

Answer

CORS is a browser security mechanism that restricts cross-origin HTTP requests. In Express, the 'cors' middleware package configures appropriate headers to allow or restrict cross-origin access.

Question 5

What status code should a REST API return when a resource is successfully created?

Accepted Answer

201 Created

Answer

HTTP 201 Created indicates that the request succeeded and a new resource was created. The response typically includes the created resource or a Location header pointing to it.

Node.js Practice Test

Node.js Practice Test

Node.js Express.js & REST APIs