Sure, let's compare NestJS and Express, two popular frameworks for building web applications in Node.js.

1. Architecture:

  • Express: Express is a minimalist web framework for Node.js that provides a simple and flexible way to build web applications. It offers basic features for handling HTTP requests and responses. Express follows a more traditional, unopinionated approach, allowing developers to structure their applications as they see fit.

  • NestJS: NestJS is a progressive Node.js framework for building efficient, reliable, and scalable server-side applications. It's built with TypeScript and heavily inspired by Angular, which means it follows a modular, component-based architecture. NestJS provides built-in support for features like dependency injection, middleware, and decorators, making it well-suited for building large-scale applications.

2. Features:

  • Express:

    • Lightweight and minimalistic.
    • Unopinionated, giving developers more freedom in structuring their applications.
    • Extensive middleware ecosystem for adding functionality to the application.
    • Great for building simple REST APIs or small to medium-sized applications.

  • NestJS:

    • Opinionated architecture with built-in support for modules, controllers, services, and middleware.
    • Strongly typed with TypeScript, providing better type safety and tooling.
    • Built-in support for features like dependency injection, decorators, and object-relational mapping (ORM) libraries.
    • Comprehensive documentation and community support.
    • Suitable for building complex, enterprise-level applications.

3. Code Examples:

Express:

const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

NestJS:

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

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

In the NestJS example above, AppModule represents the root module of the NestJS application. It typically includes metadata such as controllers, services, and other providers.

Conclusion:

  • Use Express if you prefer a lightweight, minimalist framework and need the flexibility to structure your application as you see fit.

  • Use NestJS if you prefer a more opinionated framework with built-in support for features like dependency injection, decorators, and modular architecture. NestJS is particularly well-suited for building large-scale, enterprise-level applications.