If you're a web developer and have worked with Node.js, you're probably familiar with Express.js. It's a very popular and flexible library, but as projects grow, it can become difficult to manage. This is where NestJS comes in—a progressive framework for building server-side applications with TypeScript.

✨ What is NestJS?

NestJS is a Node.js framework based on TypeScript that uses modular architecture and incorporates concepts from object-oriented programming (OOP), functional programming (FP), and reactive programming (RP). It's designed to be scalable and structured, making it ideal for large projects.

🌟 How Does It Work?

NestJS is built on the following key components:

1. Modules

Modules are the core of NestJS. They help organize the application into reusable and maintainable parts.

import { Module } from "@nestjs/common";
import { UsersModule } from "./users/users.module";

@Module({
  imports: [UsersModule],
})
export class AppModule {}

2. Controllers

They handle HTTP requests and return the necessary responses.

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

@Controller("users")
export class UsersController {
  @Get()
  findAll() {
    return "List of users";
  }
}

3. Services

They contain the business logic and can be injected into controllers.

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

@Injectable()
export class UsersService {
  getUsers() {
    return ["John", "Maria", "Carlos"];
  }
}

4. Decorators

These are functions that help structure the code declaratively. Some examples include @Controller(), @Get(), @Injectable(), etc.

🌟 Advantages of NestJS

Scalable structure: Organizes code in a modular and clean way.
Built-in TypeScript: Reduces errors and improves maintainability.
Dependency injection: Facilitates code reuse and modularization.
Compatible with Express and Fastify: Choose your preferred HTTP engine.
Large community and documentation: Well-supported and constantly growing.

📉 Disadvantages of NestJS

Learning curve: If you're coming from Express.js, adapting to the modular structure may take time.
Initial complexity: For small projects, NestJS might feel like overkill.
Heavy use of decorators: Not all developers are familiar with them.

👨🏻‍💻 My Opinion on NestJS

The first time I saw NestJS, it felt intimidating. The initial structure includes a lot of boilerplate code, which can be overwhelming for newcomers. Also, its resemblance to Angular (as it is inspired by it) made me question whether it was the right choice for me.

However, as I started using it, I realized that its initial complexity translates into a great advantage in the long run. Almost every feature you might need has probably already been considered by the NestJS team. From validation with class-validator, database integrations like PostgreSQL and MongoDB, caching, logging, file uploads, and OpenAPI documentation, to support for WebSockets and microservices with Redis, Kafka, RabbitMQ, and more. Personally, I’ve used it with Kafka, and the integration is flawless. Additionally, its CLI is a powerful tool that speeds up the creation of new components.

I’ve seen a lot of criticism toward NestJS, especially regarding performance, comparing it to Express.js. But these comparisons don’t make sense: NestJS runs on top of Express.js (or Fastify if you prefer) and adds functionalities that streamline development. It’s like building an application with Express.js and manually adding dozens of packages to achieve the same features that NestJS already provides out of the box.

Ultimately, the decision to use NestJS depends on your needs and goals. If you need maximum flexibility and speed, Express.js is a great option. But if you want a scalable, well-structured application from the start, NestJS is the perfect choice. Would I recommend it? Absolutely. For me, it has become my go-to choice for backend development, and so far, it has never let me down.

🚀 Conclusion

If you're looking for a framework to build scalable, maintainable backend applications with a well-defined structure, NestJS is an excellent choice. Its TypeScript integration, modularity, and ecosystem make it one of the best alternatives to Express.js.

💡 Give it a try and let me know your experience!

🌟 NestJS - The Backend Framework You Were Looking For