Export using .cjs / .mjs extensions

[thislooksfun]

Currently all the output files are using the .js extension. This is an issue because if the package.json file has "type": "module", then all the cjs/*.js imports error with the error:

require() of ES Module <file>.js from <file>.cjs not supported.
index.js is treated as an ES module file as it is a .js file whose nearest parent package.json contains "type": "module" which declares all .js files in that package scope as ES modules.
Instead rename index.js to end in .cjs, change the requiring code to use dynamic import() which is available in all CommonJS modules, or change "type": "module" to "type": "commonjs" in <path>/package.json to treat all .js files as CommonJS (using .mjs for all ES modules instead).

And, I suspect that the reverse is true as well (trying to import from a package without "type": "module"), though I haven't verified it.

In order to properly support these imports could you please either:

• switch based on the package.json's "type":
  • with "type": "module", CommonJS files end in .cjs and ESM files end in .js
  • without "type": "module", CommonJS files end in .js and ESM files end in .mjs
• or just always have all CommonJS files end in .cjs and all ESM files end in .mjs

I believe this is the cause of solidjs-community/solid-aria#75.

[sachaw]

The better way to handle this is to use the exports and main fields in package.json instead of using more file extensions that may not be supported in the future.

[amoutonbrady]

Fixed in commit #da278453a09648f716e24828ea3b64cd0fe9eabe