Recent versions of Typescript also pay attention to JSDoc type hints and will even check them for you and start reporting "lint errors" if you just add a `// @ts-check` magic comment to the file. It can be a particularly quick way to bootstrap a project with a lot of JS a file at a time towards static typing. (Personally, I still prefer the "rip off the bandaid" approach of just renaming every JS file to TS and fix compile errors until it builds, but it's great to have options.)