We recently switched to esm and it wasn't that painful. Ok, you have to put .js on imports, it's quite easy to search replace this with regex. Any modules that

We recently switched to esm and it wasn't that painful. Ok, you have to put .js on imports, it's quite easy to search replace this with regex. Any modules that didn't work (e.g. mocha) were switched over to more modern equivalents (vitest). This is probably a good thing. We also export ESM and CommonJS source in our packages by first transpiling to ESM then using vite to convert to CommonJS. It works really well and allows us to use our packages in both environments.