TypeScript Development (2025) Core Principles - Strict typing : Enable all strict checks - Parse, don't validate : Transform untrusted data at boundaries - Composition over inheritance : Small, focused functions - Explicit over implicit : No , prefer Toolchain Quick Patterns Type Guards Discriminated Unions Utility Types tsconfig.json Essentials References - PATTERNS.md - Code patterns and style - REACT.md - React component patterns - TESTING.md - Testing with vitest Commands --- Gotchas - with and named exports : type-only import of a value triggers errors. Fix: (inline marker). - on object:…