The TypeScript language specification is available under Open Web Foundation and the compiler implementation is available as Open Source.
Anders Hejlsberg, Steve Lucco, and Luke Hoban join us for a casual chat about - what else - TypeScript. Why did they do it? What's the backstory? How is TS related to Dart and does it really aim to solve the same problems? What's wrong with JS, anyway? Does TS extend JS or is it just a design time tool that adds semantic structure where there is none? What about ECMAScript 6 - won't that release of JS have modules and classes? Is Anders still working on C#? TypeScript and Windows Store HTML5 apps.
As usual, this is a conversation and as such just happened as it did. Tune in.
If you haven't already, you should watch Anders' solo presentation above before watching this.