JavaScript has grown from a webpage toy to being used in large-scale deployments both on the server and in the browser. This rapid growth has outpaced the growth of the language itself, which lacks features that allow teams to communicate requirements and build applications safely. This session will be a guided tour of TypeScript, a new language and toolset that makes it easier to write cross-platform, application-scale JavaScript. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. TypeScript adds optional static types, classes, and modules to JavaScript to enable great tooling and better structuring of large JavaScript applications. The TypeScript compiler is open source, cross-platform and open specification, and is written in TypeScript. The compiler outputs standard JavaScript that runs in any browser or any host.