Read original post by Fons Sonnemans at Reflection it
Microsoft announced TypeScript last week. TypeScript is a superset of JavaScript that combines type checking and static analysis, explicit interfaces, and best practices into a single language and compiler. It is an open source programming language developed by Microsoft. If you haven't investigated yet make sure you do. The related links below might help you.
What Microsoft didn't do (yet) is add TypeScript support to JavaScript Windows Store apps. In this blog I will explain how to add this support to Visual Studio so you can use TypeScript in all your Windows 8 apps.