> I've never heard of people putting typescript into a .js file - is that some node thing? Node won't load TS files by default at all. You need complicated pl

> I've never heard of people putting typescript into a .js file - is that some node thing? Node won't load TS files by default at all. You need complicated plugins like ts-node and few people know/setup ts-node, and I believe ts-node still expects Typescript code to be in TS files. It's likely accidental babel "bleedover" in that at this point even non-Typescript babel presets will strip Typescript types without warning.