@nestjs/common

What is @nestjs/common?

The @nestjs/common package is a core part of the NestJS framework, which is a framework for building efficient, reliable and scalable server-side applications. This package provides a wide range of basic functionalities necessary for any NestJS application, including decorators, modules, middleware, filters, pipes, guards, and utilities for handling HTTP requests and responses.

What are @nestjs/common's main functionalities?

Decorators

Decorators are used to annotate classes and their members to define their roles within the application. For example, `@Injectable()` marks a class as a service that can be injected, and `@Controller()` defines a class as a controller with a specific route.

@Injectable()
class MyService {}

@Controller('my-route')
class MyController {
  constructor(private myService: MyService) {}
}

Modules

Modules are used to organize components by encapsulating them within bounded contexts. This code sample demonstrates how to define a module that includes controllers and providers.

@Module({
  imports: [],
  controllers: [MyController],
  providers: [MyService],
})
class MyModule {}

Middleware

Middleware are functions that execute during the request-response cycle. They can perform tasks like logging, request validation, etc. This code sample shows a basic middleware that logs a message on each request.

@Injectable()
class MyMiddleware implements NestMiddleware {
  use(req: Request, res: Response, next: NextFunction) {
    console.log('Request...');
    next();
  }
}

Exception Filters

Exception filters handle exceptions that occur during the processing of a request. This code sample demonstrates a filter that catches HTTP exceptions and formats the response.

@Catch(HttpException)
class HttpExceptionFilter implements ExceptionFilter {
  catch(exception: HttpException, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse<Response>();
    const status = exception.getStatus();

    response
      .status(status)
      .json({
        statusCode: status,
        timestamp: new Date().toISOString(),
        path: ctx.getRequest<Request>().url,
      });
  }
}

Other packages similar to @nestjs/common

express

Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications. While it serves a similar purpose in building server-side applications, it is less opinionated than NestJS and does not provide the same level of structure and abstraction out of the box.

koa

Koa is a new web framework designed by the team behind Express, aiming to be a smaller, more expressive, and more robust foundation for web applications and APIs. Koa uses async functions, which allows for a simpler and more powerful way to handle asynchronous operations compared to Express. However, like Express, it is less opinionated than NestJS.

hapi

Hapi is a rich framework for building applications and services, allowing developers to focus on writing reusable application logic instead of spending time building infrastructure. It is designed to be more configurable and extensible than Express, offering a more comprehensive set of features out of the box. However, it still lacks the full-fledged module system and decorators provided by NestJS.

README

A progressive Node.js framework for building efficient and scalable server-side applications.

Description

Nest is a framework for building efficient, scalable Node.js server-side applications. It uses modern JavaScript, is built with TypeScript (preserves compatibility with pure JavaScript) and combines elements of OOP (Object Oriented Programming), FP (Functional Programming), and FRP (Functional Reactive Programming).

Under the hood, Nest makes use of Express, but also, provides compatibility with a wide range of other libraries, like e.g. Fastify, allowing for easy use of the myriad third-party plugins which are available.

Philosophy

In recent years, thanks to Node.js, JavaScript has become the “lingua franca” of the web for both front and backend applications, giving rise to awesome projects like Angular, React and Vue which improve developer productivity and enable the construction of fast, testable, extensible frontend applications. However, on the server-side, while there are a lot of superb libraries, helpers and tools for Node, none of them effectively solve the main problem - the architecture.

Nest aims to provide an application architecture out of the box which allows for effortless creation of highly testable, scalable, loosely coupled and easily maintainable applications. The architecture is heavily inspired by Angular.

Getting started

• To check out the guide, visit docs.nestjs.com. :books:
• 要查看中文 指南, 请访问 docs.nestjs.cn. :books:
• 가이드 문서는 docs.nestjs.com에서 확인하실 수 있습니다. :books:
• ガイドは docs.nestjs.comでご確認ください。 :books:

Questions

For questions and support please use the official Discord channel. The issue list of this repo is exclusively for bug reports and feature requests.

Issues

Please make sure to read the Issue Reporting Checklist before opening an issue. Issues not conforming to the guidelines may be closed immediately.

Consulting

With official support, you can get expert help straight from Nest core team. We provide dedicated technical support, migration strategies, advice on best practices (and design decisions), PR reviews, and team augmentation. Read more about support here.

Support

Nest is an MIT-licensed open source project. It can grow thanks to the sponsors and support from the amazing backers. If you'd like to join them, please read more here.

Principal Sponsors

Gold Sponsors

Silver Sponsors

Sponsors

Backers

Stay in touch

• Author - Kamil Myśliwiec
• Website - https://nestjs.com
• Twitter - @nestframework

License

Nest is MIT licensed.