Mastering Typescript

This is a comprehensive TypeScript reference that covers the modern ecosystem: type system fundamentals, generics, mapped and conditional types, plus framework integration with React 19, NestJS 11, and LangChain.js. It's built around TypeScript 5.9+ with strict mode defaults and includes practical patterns for Zod validation, discriminated unions, and the satisfies operator. Use it when you're migrating JavaScript codebases, setting up type-safe toolchains with Vite 7 and pnpm, or need quick reference for advanced type patterns. The framework sections are especially useful if you're bouncing between React frontends and NestJS backends and want consistent typing patterns across both.