Use Type Operations and Generic Types to Avoid Repeating Yourself

Overview

Apply DRY (Don't Repeat Yourself) to types, not just code.

Type duplication causes the same problems as code duplication: inconsistency, maintenance burden, and bugs. Use TypeScript's type operations to derive types from other types.

When to Use This Skill

• Copying fields between interfaces
• Multiple types share common properties
• Want one type to be a subset of another
• Types should stay in sync automatically
• Need to create optional/partial versions of types

The Iron Rule