NestJS Technology & Digital Applications 2

Question 1

Which NestJS decorator is used to define a class as a WebSocket gateway?

Accepted Answer

@WebSocketGateway()

Answer

@WebSocketGateway() marks a class as a WebSocket gateway, enabling real-time bidirectional communication.

Question 2

In NestJS, what is the purpose of the ConfigModule?

Accepted Answer

To load and expose environment variables application-wide

Answer

ConfigModule loads environment variables (via .env files or process.env) and makes them accessible via ConfigService throughout the app.

Question 3

Which built-in NestJS pipe validates and transforms incoming request data against a DTO class?

Accepted Answer

ValidationPipe

Answer

ValidationPipe uses class-validator decorators on DTOs to automatically validate and optionally transform incoming request payloads.

Question 4

What does the `@MessagePattern()` decorator do in a NestJS microservice?

Accepted Answer

Maps an incoming message pattern to a handler method

Answer

@MessagePattern() tells the microservice which message pattern (string or object) should trigger a specific handler method.

Question 5

How does NestJS implement the concept of 'lazy loading' for modules?

Accepted Answer

Via the LazyModuleLoader service to load modules on-demand at runtime

Answer

LazyModuleLoader allows modules to be loaded on-demand at runtime rather than at application startup, reducing initial load time.

NestJS Practice Test