After using TypeScript for the past couple of years, I've come to see it as simply another "embrace and extend" maneuver by Microsoft carve off a chunk of JavaScript mindshare, preying upon the naïveté of less-experienced developers who've fallen for the "static typing is safer" myth. TypeScript's decision to disallow JSDoc within .ts files [1] for example doesn't contribute anything positive to my impression of this syntactic pocket-protector. While the type hinting it provides is useful, the tradeoffs of added complexity, tool dependencies, and cross-compiling phase have made it more trouble than its worth in my opinion, particularly since tooling to provide code introspection and type hinting has already existed for a long time [2]. For new projects, I've begun using straight JSDoc, which is working beautifully with minimal setup [3] and provides all of the benefits I ever found useful about TypeScript, while remaining completely unobtrusive otherwise[4].
1. https://github.com/microsoft/TypeScript/issues/20774
2. https://ternjs.net/
3. https://medium.com/@trukrs/type-safe-javascript-with-jsdoc-7...
4. https://fettblog.eu/typescript-jsdoc-superpowers/