typescriptlisted

# TypeScript — Skills Reference ## Overview TypeScript is a statically typed superset of JavaScript maintained by Microsoft. The goal of this skill is the working competence a strong TypeScript engineer applies: using the type system to make illegal states unrepresentable, without fighting the compiler or hiding behind `any`. There is no official TypeScript certification; competence is anchored to the TypeScript Handbook and official release notes. **Scope of this skill:** the TypeScript type system and compiler toolchain — type syntax, inference, narrowing, generics, configuration, and declaration files. Framework usage (React JSX, Next.js server components, Node.js APIs) is deferred to the sibling skills (`react`, `nextjs`, `nodejs`). > **Load this skill when…** designing or reviewing type models (discriminated unions, generics, mapped types); configuring `tsconfig.json` (strictness, module resolution, project references); authoring or fixing `.d.ts` declaration files; migrating a JavaScript codebase to TypeScript. > **Not this skill:** React component and hook typing → see `react`; Node.js API typing in the context of building a service → see `nodejs`; Next.js server-component typing → see `nextjs`; React Native/Expo typing → see `react-native`. > Study resources and version history live in > [references/study-resources.md](references/study-resources.md) — load that file when planning > a learning path or verifying a version-specific fact. > **Verify steps assume not