Generics are supported via `@template`
https://www.typescriptlang.org/docs/handbook/type-checking-j...types can be imported either explicitly via `require()` or via the `@type {import("foo").Bar}`
There are definitely some limitations and caveats, like `Object` being aliased to `any` (I think this is being changed in a new version), but it's still way better than untyped JS, and having typescript integration is nice since our devs are already using typescript in other places.
Can even using things like https://github.com/typescript-eslint/typescript-eslint
Flow is both more advanced and faster than Typescript, but the community isn't as large, so Typescript continues to gain marketshare