We built Kangaroom (http://kangaroom.co.uk/ http://kangaroom.co.uk/) entirely using TypeScript. There are tens of thousands of lines of code. The optional typ

We built Kangaroom (http://kangaroom.co.uk/ http://kangaroom.co.uk/) entirely using TypeScript. There are tens of thousands of lines of code. The optional typing ability is a life saver when your code base grows. We've used the integrated tooling with Visual Studio which also helped a lot. Microsoft is promising it will be kept in sync with ECMAScript 6, so we don't really think there is much risk in using it. It's definitely helped with productivity, and the learning curve isn't high for JavaScript developers.