JavaScript has established itself as one of the most versatile and widely used languages in web application development. This has been largely made possible through frameworks such as Express.js, which enables developers to build robust server-side applications. However, with the rise in the level of complexity within the applications developed, the demand for more structured, maintainable, and scalable frameworks is increasing. Enter NestJS, the progressive Node.js framework built on top of TypeScript, which gained popularity in no time for the simplicity of building complex applications.
This article is about what NestJS is, why it's better than Express for many use cases, and how to get started with it.
What is NestJS ?
NestJS is a framework that helps in creating efficient, reliable, and scalable server-side applications. It is developed on top of Node.js and uses TypeScript, making it the perfect option for developers who have a preference for type safety and structured code. At its core, NestJS is inspired by Angular, drawing many of the design principles in use, including decorators, dependency injection, and modularity.
Key Features of NestJS:
TypeScript Support: NestJS is built with TypeScript, providing developers with type safety and the ability to catch errors at compile time.
Modular Architecture: Applications in NestJS are divided into modules, making the codebase easier to organize and scale.
Built-in Dependency Injection: Dependency injection simplifies application development by managing object lifetimes and resolving dependencies.
Extensibility: NestJS is highly extensible and integrates seamlessly with a variety of libraries and tools, such as TypeORM, Mongoose, and GraphQL.
Platform Independence: You can use NestJS to build applications for REST APIs, GraphQL, WebSockets, and even microservices.
Rich Ecosystem: With a large number of decorators, middleware, and prebuilt modules, NestJS simplifies complex application development tasks.
Why is NestJS Better Than Express ?
While Express.js is a minimalist framework that provides a straightforward way to build server-side applications, it lacks many features required for enterprise-level applications. NestJS addresses these shortcomings and offers several advantages:
1. Scalability and Maintainability
Express.js projects often become difficult to maintain as they grow because it lacks a structured approach. In contrast, NestJS’s modular architecture allows developers to break the application into smaller, reusable, and easily manageable modules. This structure makes scaling applications more intuitive.
2. TypeScript Advantage
Although you can use TypeScript with Express, it’s not as seamless as with NestJS. NestJS is built from the ground up to leverage TypeScript, ensuring better integration, type safety, and robust tooling.
3. Built-in Features
Express provides only the basics for building a web server. Developers often need to integrate third-party libraries for features like validation, dependency injection, or authentication. NestJS, on the other hand, offers many of these features out of the box, saving time and reducing boilerplate code.
4. Decorators and Metadata
Inspired by Angular, NestJS uses decorators to define routes, middleware, and services. These decorators provide a declarative approach to coding, which is more readable and maintainable compared to the imperative approach in Express.
5. Built-in Dependency Injection
Dependency injection is a core concept in NestJS, enabling developers to manage application dependencies efficiently. In Express, developers often rely on manual implementations or external libraries for similar functionality.
6. Support for Microservices
NestJS has first-class support for microservices architecture. It includes features like message patterns and event-based communication, making it easier to build distributed systems. Express lacks such built-in capabilities.
7. Community and Ecosystem
NestJS has a vibrant and active community, along with extensive documentation and tutorials. While Express also has a strong community, the structured approach of NestJS makes it more approachable for beginners and enterprises alike.
How to Start with NestJS
Getting started with NestJS is straightforward, thanks to its well-documented CLI and intuitive structure. Below is a step-by-step guide to setting up your first NestJS application.
Step 1: Install Node.js
Before you begin, make sure you have Node.js installed on your system. You can download it from the official Node.js website. Verify the installation by running:
node -v
npm -v
Step 2: Install the NestJS CLI
NestJS provides a Command Line Interface (CLI) tool to streamline the creation of new projects and modules. Install it globally using npm:
npm install -g @nestjs/cli
Step 3: Create a New Project
Generate a new NestJS project using the CLI:
nest new my-first-nest-app
The CLI will prompt you to choose a package manager (npm or yarn). Once selected, it will install the necessary dependencies.
Step 4: Navigate to the Project Directory
Move into the newly created project folder:
cd my-first-nest-app
Step 5: Understand the Folder Structure
NestJS projects have a well-defined structure:
src/app.module.ts: The root module of the application.
src/main.ts: The entry point of the application.
src/controllers: Directory for controllers to handle incoming requests.
src/services: Directory for services to handle business logic.
Step 6: Start the Development Server
To start the server, run:
npm run start
By default, the application will be available at http://localhost:3000.
Step 7: Create Your First Module
Use the CLI to generate a new module. For example, to create a users module:
nest generate module users
This will create a new directory src/users with a users.module.ts file.
Step 8: Create a Controller and Service
Generate a controller and service for the users module:
nest generate controller users
nest generate service users
The users.controller.ts file handles HTTP requests, while the users.service.ts file contains the business logic.
Step 9: Define Routes and Logic
In the users.controller.ts, define routes:
import { Controller, Get } from '@nestjs/common';
import { UsersService } from './users.service';
@Controller('users')
export class UsersController {
constructor(private readonly usersService: UsersService) {}
@Get()
findAll() {
return this.usersService.findAll();
}
}
In the users.service.ts, implement the business logic:
import { Injectable } from '@nestjs/common';
@Injectable()
export class UsersService {
findAll() {
return ['User1', 'User2', 'User3'];
}
}
Step 10: Test Your Application
Restart the development server and visit http://localhost:3000/users in your browser or use a tool like Postman to verify the response.