NestJS Introduction 4

Question 1

Which CLI command generates a new service in NestJS?

Accepted Answer

nest generate service users

Answer

'nest generate service users' (or 'nest g s users') creates a service file with @Injectable() and updates the module automatically.

Question 2

What does the @Controller('cats') decorator argument specify?

Accepted Answer

The route prefix for all handlers in that controller

Answer

The string passed to @Controller() sets the path prefix, so @Controller('cats') means all routes in that class are under /cats.

Question 3

In NestJS, where is dependency injection typically performed for a service?

Accepted Answer

Via the constructor using constructor-based injection

Answer

NestJS resolves dependencies declared in the constructor, automatically providing the correct instances at runtime.

Question 4

Which built-in NestJS module provides configuration management and environment variables?

Accepted Answer

@nestjs/config

Answer

@nestjs/config wraps dotenv and provides a ConfigService for accessing environment variables in a type-safe way.

Question 5

What is 'middleware' in NestJS and when does it execute?

Accepted Answer

A function that runs before the route handler in the request lifecycle

Answer

Middleware in NestJS functions identically to Express middleware — it has access to req, res, and next() and runs before route handlers.

NestJS Practice Test