Comment by somebee
4 years ago
There is built-in type-checking, but currently only via the tooling. It integrates with TS as a language service plugin (https://github.com/Microsoft/TypeScript/wiki/Writing-a-Langu...) so you get great warnings/errors, type inference and much more. To define standalone types or interfaces you still need to use `.d.ts` files, but that may change in the future :)
that is to say, the types are not part of the syntax in any way?
You can typeset variables, parameters etc (ie. see the code in https://dev.to/somebee/global-type-augmentations-with-automa...). But declaring standalone types is still done in `.d.ts` files. Imho, the type inference in ts/js is getting so good that I very rarely need to declare any explicit types in my own projects.