NestJS Introduction

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NestJS is a powerful back-end framework for building efficient, scalable, and maintainable Node.js applications. It's built on top of TypeScript, which provides a strong foundation for developing modern, statically-typed applications. One of the key features of NestJS is its highly modular architecture that encourages developers to follow best practices and create well-organized, reusable components.

Why NestJS?

NestJS is designed to help developers create highly testable, scalable, and loosely-coupled applications. It combines the best aspects of object-oriented programming, functional programming, and reactive programming, while leveraging popular libraries and tools like Express and RxJS. In other words, NestJS is a one-stop-shop for developing modern, versatile, and maintainable applications.

NestJS Architecture

The architecture of NestJS is highly inspired by Angular, which makes it easy for developers with Angular experience to pick it up quickly. The main building blocks of a NestJS application are modules, controllers, and providers.

Modules

A module in NestJS is a class decorated with @Module(). It serves as a container for organizing related components, such as controllers and providers, in a coherent way. Modules help to keep the application structure clean and maintainable.

import { Module } from "@nestjs/common";
import { ExampleController } from "./example.controller";
import { ExampleService } from "./example.service";

@Module({
  controllers: [ExampleController],
  providers: [ExampleService],
})
export class ExampleModule {}

Controllers

A controller in NestJS is responsible for handling incoming HTTP requests and returning a response. Controllers are classes decorated with @Controller(), and they define the routes and request handlers for the application.

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

@Controller("example")
export class ExampleController {
  @Get()
  getExample(): string {
    return "Hello from the ExampleController!";
  }
}

Providers

Providers in NestJS are classes, values, or factories that can be injected into other components, such as controllers or other providers. They are used to encapsulate and share functionality across the application. Providers are decorated with @Injectable() when they are classes.

import { Injectable } from "@nestjs/common";

@Injectable()
export class ExampleService {
  getMessage(): string {
    return "Hello from the ExampleService!";
  }
}

Getting Started with NestJS

To start building an application with NestJS, you'll need to have Node.js and TypeScript installed on your machine. You can then use the NestJS CLI to generate a new project:

npm i -g @nestjs/cli
nest new my-nestjs-project

This will create a new NestJS project with a basic structure, including a root module, a sample controller, and a sample provider. From there, you can begin to explore the many powerful features and libraries that NestJS has to offer.

As you can see, NestJS provides a robust and scalable foundation for building modern, maintainable Node.js applications. Its modular architecture, inspired by Angular, ensures that your code stays clean and well-organized. So, put on your NestJS hat and start building the next big thing!

FAQ

npm i -g @nestjs/cli

nest new project-name

cd project-name
npm run start