TypeScript

TypeScript is a typed superset of JavaScript that compiles to plain JavaScript.
Site: http://www.typescriptlang.org

Books

Added Deep Dive in TypeScript

The definitive guide to TypeScript. Dive into all the details that a JavaScript developer needs to know to be a great TypeScript developer.

 Free book

Added Typescript Succinctly

Jump into Microsoft's open-source superset of JavaScript with TypeScript Succinctly.

 Free book