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TypeScript is looked upon very highly by everyone at MS and I haven't seen any new projects started with vanilla JS in the last few years. No one needs to encourage anyone to use it. It's just the obvious choice for large projects (and every project at MS is large).

Some other products using it off the top of my head: Azure Machine Learning, Xbox Music, Visual Studio Team Services. EVERYTHING new.

Sadly, Microsoft's main JS library for UI development - WinJS 4.x is _not_ TypeScript enabled.

While WinJS is not built in TypeScript, there are TypeScript bindings for it[0] bundled in the WinJS repo, so it's easy to use from TypeScript.

[0]: https://github.com/winjs/winjs/tree/master/typings

VS Code, IE11/Edge's F12 developer tools, and Sway (Office) use it to name only a few.

VS Code's source: https://github.com/Microsoft/vscode

The new Azure portal uses TypeScript heavily.