[netcraft]

There is a significant difference between TS and a non-standard anything. Nothing goes into typescript until it is stage 3, meaning intent to ship. There is now two compilers supporting the syntax. It is well supported.

Also, if that was a concern I would be willing to say we start out with jsdoc style types - I would much prefer the regular syntax and would like to use things like enums, but it would be a massive improvement over not having it.

In my mind, you are writing javascript with types whether you use typescript or not - using TS makes those types explicit and allow a compiler to check your work, on top of the other benefits.

I will rephrase though - instead of "there are no downsides" I'll say "Any downsides I have found are minute in comparison to the benefits", but my intent behind bringing this up in the first place is to hear from anyone else who does see more downsides than I do and to understand those.