First NestJS application - Mini Project: Build & Apply

First NestJS application

📖 Scenario: You want to create a simple web server using NestJS that responds with a greeting message when accessed.

🎯 Goal: Build a basic NestJS application with a controller that returns 'Hello, NestJS!' when visiting the root URL.

📋 What You'll Learn

Create a NestJS application main file

Set up a controller named AppController

Add a route handler for GET requests on the root path /

Return the exact string 'Hello, NestJS!' from the route handler

💡 Why This Matters

🌍 Real World

NestJS is used to build scalable and maintainable server-side applications with TypeScript and Node.js. This project shows how to start a simple web server.

💼 Career

Understanding how to create a basic NestJS app is essential for backend developers working with modern Node.js frameworks in professional environments.

1

Create the main application bootstrap file

Create a file named main.ts and write code to bootstrap a NestJS application using NestFactory.create(AppModule). Import AppModule from ./app.module. Use await app.listen(3000) to start the server on port 3000.

NestJS

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

async function bootstrap() {
  // Your code here
}

bootstrap();

Need a hint?

Use NestFactory.create(AppModule) to create the app and app.listen(3000) to start the server.

2

Create the application module

Create a file named app.module.ts. Import Module from @nestjs/common. Define a class AppModule decorated with @Module that declares AppController in its controllers array. Import AppController from ./app.controller.

NestJS

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';

// Your code here

Need a hint?

Use @Module decorator with controllers array including AppController.

3

Create the application controller

Create a file named app.controller.ts. Import Controller and Get from @nestjs/common. Define a class AppController decorated with @Controller(). Add a method getHello() decorated with @Get() that returns the string 'Hello, NestJS!'.

NestJS

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

// Your code here

Need a hint?

Use @Controller() on the class and @Get() on the method returning the greeting string.

4

Run and verify the NestJS application

Ensure all files are saved. Run the NestJS application using npm run start or node dist/main.js after building. Visit http://localhost:3000/ in a browser to see the text 'Hello, NestJS!'. Add the @Controller() decorator to AppController if missing.

NestJS

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

@Controller()
export class AppController {
  @Get()
  getHello(): string {
    return 'Hello, NestJS!';
  }
}

// Your code here to confirm the controller decorator is present

Need a hint?

Make sure the @Controller() decorator is present on AppController to handle routes.