NestJS

NestJS (or simply Nest) is a progressive Node.js framework for building efficient, reliable, and scalable server-side applications. Nest provides an out-of-the-box application architecture which allows for the effortless creation of highly testable, scalable, loosely coupled, and easily maintainable applications.

Foundations of NestJS

Nest is built with and fully supports TypeScript (yet still enables developers to code in pure JavaScript) and combines elements of Object-Oriented Programming (OOP), Functional Programming (FP), and Functional Reactive Programming (FRP).

Under the hood, Nest makes use of robust HTTP Server frameworks like Express (the default) and can optionally configure to use Fastify as well!

Nest provides a level of abstraction above these common Node.js frameworks (Express/Fastify), but also exposes their APIs directly to the developer. This gives developers the freedom to use the myriad of third-party modules which are available for the underlying platform.

First Steps with Nest

To start using Nest, you first need to install the Nest CLI. Open your terminal and type:

npm install -g @nestjs/cli

Once installed, you can create a new Nest project with:

nest new project-name

Navigate into your project folder and start adding modules, controllers, and services as needed.

A Simple Nest Application

Here's a simple controller in a Nest application:

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

@Controller('hello')
export class HelloController {
  @Get()
  getHello(): string {
    return 'Hello Nest!';
  }
}

To wire everything up, you'll need a module:

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

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

And finally, you can bootstrap the application:

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

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(3000);
  console.log(`Application is running on: ${await app.getUrl()}`);
}
bootstrap();

Run the application using:

pnpm start:dev

When the server is running, navigate to http://localhost:3000/hello in your browser. You should see the "Hello Nest!" message.

Leveraging NestJS Features

NestJS provides a comprehensive set of features for building modern web applications:

• Modularity: NestJS modules are singletons by default and can be easily organized and shared.
• Middleware: NestJS middleware are functions that run before the route handler.
• Exception filters: NestJS provides a way to catch exceptions that are thrown during the handling of a request.
• Pipes: Pipes operate on the arguments to be processed by the route handler, just before the handler is called.
• Guards: Guards determine whether a given request will be handled by the route handler.
• Interceptors: Interceptors extend the basic functionality of Nest, allowing you to bind extra logic before / after method execution.

Conclusion

NestJS is an ideal choice for building enterprise-grade applications due to its powerful CLI, scalability, high-level abstraction, and tight integration with TypeScript. It's designed to give developers an easy-to-follow guide to build robust applications, with an architecture that's familiar to Angular developers.

By combining the elements of OOP, FP, and FRP, Nest provides a stable foundation for your server-side application, allowing you to focus on building features rather than wrestling with the setup.