Not TS, but there are plans to allow something similar with special type annotation syntax. The runtimes still won't do anything with that extra info though, it

Not TS, but there are plans to allow something similar with special type annotation syntax. The runtimes still won't do anything with that extra info though, it'll get stripped just like comments. https://github.com/tc39/proposal-type-annotations https://github.com/tc39/proposal-type-annotations