1. Basic NestJS Questions

1. What is NestJS?

NestJS is a progressive Node.js framework for building scalable and maintainable backend applications using TypeScript. It is built on top of Express.js (or Fastify) and follows an Angular-inspired modular architecture.

2. What are the main features of NestJS?

• TypeScript support

• Modular architecture

• Built-in Dependency Injection

• Support for Express.js & Fastify

• Middleware and Guards

• WebSockets and GraphQL support

3. What is the entry point of a NestJS application?

The entry point is the main.ts file. It bootstraps the application using NestFactory.create().

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(3000);
}
bootstrap();

4. What are modules in NestJS?

Modules in NestJS are used to organize the application into logical units. Each module is a class decorated with @Module().

Example:

import { Module } from '@nestjs/common';

@Module({
  imports: [],
  controllers: [],
  providers: [],
})
export class AppModule {}

5. How do you create a new module in NestJS?

Run the following CLI command:

nest g module <module-name>

2. Controllers & Routes

6. What are controllers in NestJS?

Controllers handle incoming HTTP requests and return responses. They are decorated with @Controller().

7. How do you define a simple controller in NestJS?

import { Controller, Get } from '@nestjs/common';

@Controller('users')
export class UserController {
  @Get()
  findAll() {
    return 'This action returns all users';
  }
}

8. How do you define dynamic routes in NestJS?

@Get(':id')
findOne(@Param('id') id: string) {
  return `User with ID ${id}`;
}

9. What are route parameters and how do you access them?

Route parameters are dynamic values in a route. You access them using .