Idea: Add a way to invoke from cli about cjs-es

[eight04]

If you use rollup, try output.preserveModules option with rollup-plugin-cjs-es.

A potential issue: if your module uses external libraries, those libraries may provide different entries for esm/cjs. You may have to tell the plugin how to import those external libraries. More details: https://github.com/eight04/rollup-plugin-cjs-es#missing-exports-foo-is-not-exported-by-foojs

A CLI should still be nice. It can look into external libs to determine their singature, or even raise an error if the library doesn't support ESM. Before implementing our own solution, we should compare other alternatives first e.g.

• https://github.com/getify/moduloze
• https://github.com/wessberg/cjstoesm

[eight04]

BTW it may need a resolver to rewrite the module path. You don't need extension in cjs but it is required by ESM (i.e. ./foo -> ./foo.mjs or ./foo/index.mjs)

[karfau]

Thank you for the additional details.

Another option might be to use typescript to convert the modules, https://blog.logrocket.com/publishing-node-modules-typescript-es-modules/ contains the basic concepts, here is the related typescript reference https://www.typescriptlang.org/docs/handbook/2/modules.html.

I think I'm currently leaning towards it, since we plan to generate types anyway.

You can decide yourself if you want to keep this issue open.

[eight04]

With typescript, you should probably write es import/export in ts source code and compile them into es/cjs modules.

[karfau]

With typescript, you should probably write es import/export in ts source code and compile them into es/cjs modules.

Of course that is the usual use case.
As the linked article shows, it's also possible to write code in commonjs and tell TS to write it's output as ES modules.