I tried parsing this with babel let x = 10 as const; and it doesn't work afaics. How did you make it work?

Unexpected token (1:14)

> 1 | let x = 10 as const;
                    ^

You might be right - the online repl seems like it doesn't work with TypeScript for some reason.

Doesn't the "Add plugin" button in the plugins section of the sidebar work for you?

Nope :(

Plugin @babel/plugin-transform-typescript could not be loaded

Seems like it's trying to eval the HTML on https://bundle.run/@babel/[email protected]?

@DanielRosenwasser should we wait with releasing any of this changes till typescript 3.4 is out/close to being released?

My intuition is that as soon as the 3.4.0 version is released it should be safe to release. TypeScript typically doesn't declare .0 versions stable, though, they refer to them as "RC"; but I don't think there's any precedent for them breaking grammar or emit semantics after having released a .0 version.

@typescript-eslint/parser always waits until the .1 version (the one that gets the "stable version released" publicity) is out which tbh is rather inconvenient.

@DanielRosenwasser would I be correct in my understanding that the .0 version is intended to be supported by tooling and typing authors, and the "delay" before making it "stable" is to give some time for the ecosystem to catch up? Or should it just be treated like an oddly-named beta?

Well there's typically about 2 weeks in between an RC and a release. I would just wait until TS 3.4 goes out to publish anything with this functionality. If you want to let stuff "bake" in nightly releases, that's probably a good idea and you can merge some PRs in.

We usually don't do nightly releases, we just wait to merge PRs if needed since it is much simpler 😆

So, is this released with plugin-transform-typescript 7.4.0? ... I get "SyntaxError: Unexpected token" for both, readonly tuples and as const literals...

Okay, forget it. I don't know why, but I had an outdated indirect @babel/parser package (< 7.4).