TypeScript

TypeScript is JavaScript with a type system, so learn JavaScript first and add types gradually. The official TypeScript Handbook is the clearest starting point, and the TypeScript Playground lets you see how types are checked and what JavaScript is emitted. Matt Pocock's Beginner's TypeScript course and Total TypeScript: Essentials focus on practical everyday typing.

For deeper understanding, TypeScript Deep Dive and Axel Rauschmayer's Tackling TypeScript explain how the type system behaves in real code, including generics and narrowing. Angular, Deno and webpack resources are collected in the subcategories, and the cheat sheets are handy once you start writing more advanced types.