Layered Architecture Patterns in Node.js

A layered architecture separates concerns into distinct tiers, making code easier to test, maintain, and scale.

Typical Layers

1. Controllers — Handle HTTP requests and responses.
2. Services — Contain business logic.
3. Repositories — Abstract data access.
4. Middleware — Cross-cutting concerns like auth and validation.

Benefits

• Separation of Concerns: Each layer has a single responsibility.
• Testability: Layers can be mocked and tested independently.
• Flexibility: Swap implementations (e.g., JSON file → database) without changing other layers.