Very cool.
Kudos for providing a good old-fashioned javascript library and not forcing people to use flavour of the month MVC/MVVM framework / babel-ES6-TS-god-knows-what transpiler
Typescript may be different and may be better, but there is a lot of rightly justified hesitation to adopting it.
Perhaps writing it is a bigger ask--a twenty minute session of reading and poking at the language in VSCode did it for me, but maybe I'm secretly some kind of TypeScript savant--but this just plain should not be a problem for anybody who's up on modern JS.
For awhile, React/Redux was really kind of gross with TypeScript, but even that's mostly hammered out. (React's new context API did a lot to reduce my use of Redux in general, and works pretty comfortably with TypeScript too.)
The fact that it wasn't. That's what's gonna make me actually check this out.
Well done!