Maybe it's obvious, but I checked everywhere (besides the right place) and googled it. Nothing.
If you only have TypeScript installed for Visual Studio then:
tsc -v
and hit EnterVisual Studio 2017 versions 15.3 and above bind the TypeScript version to individual projects, as this answer points out:
- Right click on the project node in Solution Explorer
- Click Properties
- Go to the TypeScript Build tab