NestJS Communication & Stakeholder Relations 4

Question 1

Which NestJS built-in class is used to emit custom events within the same application process?

Accepted Answer

EventEmitter2 via @nestjs/event-emitter

Answer

@nestjs/event-emitter wraps EventEmitter2 and integrates it with NestJS DI for in-process event communication.

Question 2

When documenting a paginated response for stakeholders, which @nestjs/swagger decorator best describes an array of items?

Accepted Answer

Both A and B are correct

Answer

Both @ApiResponse({ type: [ItemDto] }) and @ApiOkResponse({ type: ItemDto, isArray: true }) correctly declare an array response in Swagger.

Question 3

A QA team reports that WebSocket messages arrive out of order under load. Which NestJS pattern helps serialize message handling per client?

Accepted Answer

Using async/await in gateway handlers

Answer

Marking gateway handler methods as async and using await ensures sequential processing of each client's messages.

Question 4

How does NestJS support gRPC as a transport layer for inter-service communication?

Accepted Answer

Via the @nestjs/grpc package and .proto file definitions

Answer

@nestjs/microservices includes gRPC support using .proto files to define service contracts between teams.

Question 5

A security-conscious stakeholder wants API keys validated before any route is accessed. Which NestJS construct is the right tool?

Accepted Answer

Guard

Answer

Guards implement the CanActivate interface and are specifically designed for authorization and authentication decisions.

NestJS Practice Test