Hey @micahscopes, thank you for the pull request!
I have one concern which most web devs would probably find absurd:
I value the ability to simply open html file locally and have demos run without having to run a webserver, so that one needs nothing but chrome devtools to start experimenting. Do you think it's possible to preserve this capability somehow? CJS instead of ESM?

@znah oh of course, I ought to make sure the demos work. ESM would be the one that would run without any build step or server, since the browsers support direct ESM imports. The demos might actually work as-is with this PR, but I'll double check. But yeah, with ESM all you'd need to get started is chrome dev tools, and I believe you could keep your original workflow too, there's no requirement to use ESM as far as I know. This just makes it easier to use it quickly in a larger project.

I'm getting CORS errors when trying to import ESM module from "file://" (w/o local webserver)

Ah, I see, I didn't realize ESM modules can only be loaded using CORS, I thought maybe it'd be possible to load them without type="module".

Do you think it's possible to preserve this capability somehow? CJS instead of ESM?

Well yes, I see now, it'd be nice to preserve the ability to use the library as is. The "conventional" way of doing this would be to include a build step that generates ESM and IIFE versions (for classic script import) from ESM or CJS sources. But then that would make it messier to make releases.

I think I have a workaround. It's possible to "import" ordinary JavaScript using import file.js, which just runs the file. What we can do is in swissgl.js save the main function to the global scope, then create an auxiliary swissgl.mjs that imports swissgl.js and exports the main function from the global scope. I'll try it now, I think it should work and it avoids a build step!

Okay I tried it and it seems to work while also preserving the demo functionality and avoiding a build step!

+1 for this functionality

would be nice to be able to import this

Sure, I think I'm done with breaking API changes, will review and merge soon