NestJS vs Express vs Fastify comparison - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Which framework uses a modular architecture with decorators?

Among NestJS, Express, and Fastify, which framework is designed around a modular architecture using decorators to organize code?

A Express

B NestJS

C Fastify

D All three use decorators by default

💡 Hint

Think about which framework uses TypeScript features heavily.

NestJS uses decorators and a modular structure to organize code, making it more structured and scalable.

❓ component_behavior

intermediate

What is the default HTTP server used by NestJS?

By default, which HTTP server does NestJS use under the hood?

A Fastify

B Koa

C Express

D Hapi

💡 Hint

NestJS can switch servers but has a default choice.

NestJS uses Express as its default HTTP server but can be configured to use Fastify for better performance.

📝 Syntax

advanced

Which code snippet correctly creates a Fastify instance in NestJS?

Select the correct way to create a Fastify-based NestJS application.

NestJS

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';
import { FastifyAdapter, NestFastifyApplication } from '@nestjs/platform-fastify';

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

A NestFactory.create(AppModule, new KoaAdapter())

B NestFactory.create(AppModule, new ExpressAdapter())

C NestFactory.create(AppModule)

D NestFactory.create(AppModule, new FastifyAdapter())

💡 Hint

Fastify requires a specific adapter in NestJS.

To use Fastify in NestJS, you must pass a FastifyAdapter instance to NestFactory.create.

❓ state_output

advanced

What is the output when sending a GET request to a simple Express route?

Given this Express code, what will the server respond with when a GET request is made to '/'? const express = require('express'); const app = express(); app.get('/', (req, res) => { res.send('Hello from Express'); }); app.listen(3000);

A Hello from Express

B Cannot GET /

C Hello from NestJS

D 404 Not Found

💡 Hint

Look at the response sent inside the route handler.

The Express app sends 'Hello from Express' as the response to GET requests at '/'.

❓ lifecycle

expert

Which lifecycle hook runs after all modules are initialized in NestJS?

In NestJS, which lifecycle hook method is called after all modules have been initialized?

A onApplicationBootstrap()

B onModuleInit()

C afterInit()

D beforeApplicationShutdown()

💡 Hint

This hook runs once the whole app is ready, not just a single module.

onApplicationBootstrap() is called after all modules are initialized and the app is bootstrapped.