Consider publishing as an ESM module only

[dyladan]

Maybe we should consider publishing only an ECMAScript module and removing commonjs entirely from our bundle? Node 12 (our minimum node version) and later supports ES modules.

Originally posted by @dyladan in #3976 (comment)

Our dual publishing scheme has always been a little bit fragile and has caused unexpected issues in the past. I believe if we publish an ES Module with the package.json "type" of "module" we should still be able to be required by users using commonjs since node supports mixed esm/commonjs runtime.

[dyladan]

TODO: test that an ESM module can be required by a CommonJS module/app

[loren138]

Here's a writeup from another author who moved all of his packages to ESM only: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
You cannot require an ES module, you can await import() it though

[dyladan]

Thanks for the link. For now, I think the limitations are too severe for us.

[trentm]

Here is some advice in the Node.js core docs: https://nodejs.org/api/packages.html#dual-commonjses-module-packages
However, every option has limitations.