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Introduction

In the ever-evolving world of web development, NestJS has emerged as a powerful tool for building efficient, scalable, and maintainable server-side applications. This blog post will delve into three key areas: what NestJS is, its core features, why developers should consider using it and a basic overview of a Nest JS project.

NestJS, often shortened to Nest, is a rapidly rising star in the realm of Node.js frameworks. It is built with TypeScript and infused with progressive JavaScript practices, it empowers developers to create efficient, scalable, and enterprise-grade server-side applications. NestJS tackles a key challenge in the Node.js world: providing a well-defined architecture to guide and streamline development, leading to robust, maintainable, and testable applications and combines elements of Object-Oriented Programming (OOP), Functional Programming, and Functional Reactive Programming. NestJS leverages the robustness of JavaScript and taps into the advantages of TypeScript, such as static typing and the ability to use annotations.

Core Features of NestJS

  • NestJS provides a level of abstraction above these common Node.js frameworks (Express/Fastify), but also exposes their APIs directly to the developer. Hence, it allows developers the freedom of using the third-party modules which are available for the underlying platform. Moreover, it is bundled with a robust CLI tool that enhances productivity and eases the process of developing complex applications.
  • Modular Structure: Applications are built using well-defined modules, promoting code organization and reusability. Each module encapsulates its own functionalities, dependencies, and services.
  • TypeScript Support: Built primarily with TypeScript, NestJS leverages its strong typing and tooling to provide robust type safety, improved code intelligence, and better maintainability. However, it gracefully supports pure JavaScript development as well.
  • Blend of Paradigms: NestJS embraces a pragmatic approach, incorporating elements from Object-Oriented Programming (OOP), Functional Programming (FP), and Functional Reactive Programming (FRP). This allows developers to choose the paradigm that best suits their needs within the application.
  • Platform Agnostic: While Express serves as the default HTTP platform, Nest is platform-agnostic. Adapters exist for other popular frameworks like Fastify, enabling flexibility and integration with various tools and libraries.
  • Rich Ecosystem: Nest boasts a vibrant community and a growing ecosystem of modules, libraries, and tools. This extends its functionality and caters to diverse development needs.

Why Developers Should Use NestJS

  • NestJS is a versatile framework that suits a wide array of applications, from small, lightweight APIs to large, complex enterprise applications. By providing a solid architectural base and a scalable development environment, it helps to reduce technical debt and allows developers to focus more on creating application logic rather than setting up infrastructure. Furthermore, with its strong typing and easy testing capabilities, NestJS ensures that code is not only functional but also robust and maintainable.
  • APIs: Build RESTful APIs with robust routing, validation, and middleware support.
  • Microservices: NestJS excels at creating microservice architectures thanks to its modularity and clear boundaries.
  • Real-time Applications: Integrate webSockets or other real-time technologies for dynamic interactions.
  • Enterprise Applications: Its scalability, maintainability, and testing features make it ideal for large-scale enterprise projects.
  • Improved Architecture: The modular structure fosters well-organized and loosely coupled code, leading to cleaner architecture, easier maintenance, and better scalability.
  • Enhanced Developer Experience: Type safety, clear structure, and helpful tooling contribute to a smooth development experience, reducing errors and boosting productivity.
  • Scalability and Testability: The architecture promotes loosely coupled modules and dependency injection, making applications naturally scalable and easier to test.
  • Large Community and Ecosystem: The active community and rich ecosystem provide ample support, learning resources, and readily available solutions for common challenges.

Starting a Nest JS project

Prerequisites:

  • Node.js and npm (or yarn) installed on your system.
  • Basic understanding of JavaScript, TypeScript (recommended), and Node.js concepts.

Steps:

  1. Install the CLI globally: npm install -g @nestjs/cli
  2. Create a new project: nest new my-project

3. Project Structure: The project will have the following key directories:

  • src: Contains the source code for your application logic.
  • node_modules: Holds all the installed dependencies.
  • tsconfig.json: Configures the TypeScript compiler.
  • package.json: Manages project dependencies and scripts.

4. Exploring Key Concepts:

a) Modules:

Modules are the foundational building blocks of a NestJS application. They encapsulate specific functionalities and dependencies. Open src/app.module.ts to see the root module.

b) Controllers:

Controllers handle incoming requests and define routes for your application. Create a new controller file src/app/hello.controller.ts:

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

@Controller('chat')
export class HelloController {
  @Get()
  getHello() {
    return 'Hello, NestJS!';
  }
}

This controller defines a single route /hello that returns the message “Hello, NestJS!”. Similarly we may use other decorators like POST or even make our very own custom decorators.

c) Services:

Services encapsulate application logic and business rules. The endpoints are mentioned in controllers which call the functions with business logic in the service. Create a new service file src/app/hello.service.ts:

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

@Injectable()
export class HelloService {
  getHello() {
    return 'Hello from the service!';
  }
}

This service defines a simple getHello method.

d) Dependency Injection:

NestJS promotes dependency injection, where services or other dependencies are injected into controllers or other modules. In src/app.module.ts, import and inject the HelloService:

import { Module } from '@nestjs/common';
import { HelloController } from './hello.controller';
import { HelloService } from './hello.service';

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

This injects the HelloService into the HelloController, allowing its use within the controller’s methods

We may use nest g resource folder_name to generate entities, dto (data transfer objects), contoller ,service and module file by default based on the protocol which we shall use for that functionality.

e) Running the Application:

Start the NestJS application using npm run start to run the server on port 3000. Access http://localhost:3000/hello in your browser to see the response from the controller.

f) Testing:

NestJS encourages unit testing. Explore src/app.controller.spec.ts for an example of testing the controller.