js2mjs

WARNING: This modules messes up the sourcemaps. I didn't find a way to fix them.

Convert a ESM distribution that is using .js extension to an ESM distribution using .mjs extension.

Motivation

Node.js is ESM compatible but it's a bit picky about the files extension. It expects import statements to include the file extension and that .mjs be used instead of .js.
So when you setup TypeScript to output an ESM distribution it will generate a distribution that isn't compatible with Node in "type": "module" mode.
It's an ESM distribution that Vite, Next.js and other build tools will understand but not Node.
This module let you patch the distribution so it can be used with node.

yarn add --dev js2mjs
npx tsc # Build your project we assume it generate dist/esm
npx js2mjs dist/esm # Your ESM distribution using .js extension will be updated to an ESM distribution using .mjs extension