Why NestJS? A Comparison with ExpressJS

When I first began to explore NestJS, the initial question that came to mind was: why NestJS when we already have ExpressJS? To better understand this, lets start by discussing what Express and NestJS are.

NestJS:

On the other hand, NestJS is a full-fledged framework built on top of Node.js and Express, offering a structured and modular approach based on the MVC architecture. NestJS enforces a more opinionated setup, which means developers follow a predefined architecture, making the codebase more uniform and understandable across teams.

Nest.js Core Components:

1. Modules: Organize application features into separate, maintainable module.

2. Controllers: Manage incoming requests and link routes to business logic.

3. Providers: Provide dependencies to components, enhancing code organization.

4. Middleware: Process requests for tasks like authentication or logging.

5. Pipes: Validate and transform data before reaching the controller.

6. Interceptors: Alter request/response flow for tasks like logging or caching.

7. Exception Filters: Catch and manage errors, returning structured responses.

Key Features of NestJS

• Modular Architecture: Expertise in building scalable applications with a clean, modular MVC architecture.

• Dependency Injection: is a design pattern in which an object receives other objects that it depends on.

• Integration with Databases: built-in support for popular ORMs like TypeORM, Sequelize, and Mongoose.

• Microservices Architecture: supports building microservices and can easily integrate with other microservices platforms such as Kafka, Redis, and gRPC

• GraphQL Integration: support building modern GraphQL APIs for efficient frontend-backend data communication.

• WebSockets: built-in support for WebSockets, to create real-time applications and chat applications.

Pros of Nest.js:

- Excellent TypeScript Support

- Built-in Dependency Injection

- Ability to handle large-scale applications

- Structured and organized code

Cons of Nest.js:

- Steep learning curve

- Strict architectural conventions

- Large-sized app bundles

Express

ExpressJS is a minimalistic ( provides a set of features for building web and mobile applications ) and un-opinionated (means not structured define of codebase) web framework for Node.js. Some developers, consider it as a library. Its flexibility allows developers to structure their applications in any way they prefer Leaves the code structure up to the developer, which can be both an advantage and a challenge.

Express.js Core Components:

• Routing: Handles different HTTP methods and defines URL endpoints.

• Middleware: Framework for creating custom request and response handling logic.

• Error Handling: Provides ways to catch and manage errors effectively.

• Request/Response Objects: Manage incoming requests and outgoing responses.

• Templating Engines: Supports dynamic HTML generation with engines like Pug, EJS, and Handlebars.

Features of Express.js:

- Minimal and Unopinionated

- Robust Routing

- Middleware Support

- Template Engine Integration

- Easy Integration with Other Libraries

Pros of Express.js:

- Minimalistic framework

- Easy to learn

- Wide range of libraries available

- Excellent performance and stability

Cons of Express.js:

- Lack of opinionated structure

- No built-in dependency injection

- Limited error handling

- Absence of MVC pattern

Conclusion

Choosing between Nest.js and Express.js depends on your project's needs and team preferences. Express.js is ideal for smaller, lightweight applications, while Nest.js, with its structured architecture, in building larger, scalable projects. Both offer unique strengths, so pick the one that best fits your development approach. Happy coding!