NestJS NestJS 3

Question 1

What is the role of a NestJS Interceptor?

Accepted Answer

To bind extra logic before/after a method execution and transform results

Answer

Interceptors implement the NestInterceptor interface and can add extra logic around method calls, transform results, and extend basic function behavior.

Question 2

Which RxJS operator is commonly used in NestJS interceptors to transform the response?

Accepted Answer

map

Answer

The map operator from RxJS is commonly used in interceptors to transform the response stream returned by the route handler.

Question 3

What does a NestJS Pipe primarily do?

Accepted Answer

Transforms and validates input data before it reaches the route handler

Answer

Pipes implement the PipeTransform interface and are used to transform and/or validate data before it reaches the route handler.

Question 4

Which built-in NestJS pipe validates and strips non-whitelisted properties from a DTO?

Accepted Answer

ValidationPipe

Answer

ValidationPipe with whitelist:true strips properties not defined in the DTO class, and forbidNonWhitelisted:true throws an error for unexpected properties.

Question 5

Which decorator binds a pipe to a specific route parameter?

Accepted Answer

Both @UsePipes() and passing the pipe directly to @Param()/@Body()

Answer

NestJS allows binding pipes at the method level with @UsePipes() or at the parameter level by passing the pipe as an argument to @Param(), @Body(), etc.

NestJS Practice Test

NestJS Practice Test

NestJS NestJS 3