solid

Five principles for building software that is easy to understand, extend, and maintain. They reduce coupling, increase cohesion, and make code testable.

| SRP | One reason to change | "This class handles X and Y and Z" | | OCP | Add, don't modify | Growing if/else or switch chains for types | | LSP | Subtypes are substitutable | Type-checking or special-casing in calling code | | ISP | Small, focused interfaces | Empty method implementations or throw new Error("Not implemented") |

| DIP | Depend on abstractions | new ConcreteClass() inside business logic |

應用 SOLID 原則編寫靈活、可維護且可測試的程式碼。 在設計類別、介面和模組邊界時使用。封面單曲 責任、開放/封閉、里氏替換、介面隔離和 依賴倒置與實用的 TypeScript 範例和偵測啟發式。 來源：fellipeutaka/leon。