TypeScript Type-Safe JavaScript AI Skill Guide (Claude)

Overview & Engine Architecture

TypeScript adds a structural type system that erases at compile time. The compiler (tsc) and language service enforce contracts; tsconfig.json chooses module resolution, emit, and strictness. Agents prefer precise types over any, model closed states with discriminated unions, validate untrusted input at runtime (types do not exist at runtime), and fix errors at API boundaries instead of silencing them with assertions.