addaleax / gen-esm-wrapper Goto Github PK

Hello @addaleax

I'm using gen-esm-wrapper to bundle a library I develop so firstly thanks for your work 👍

A recent issue raised some questions regarding how gen-esm-wrapper works specifically in regards to default import/exports.

For the example code:

'use strict';
// This is a CommonJS module.

exports.method = () => {
  return 'hello';
};

The wrapped esm version would be:

import mod from "../index.js";

export default mod;
export const method = mod.method;

The questions are:

1. How does the default import import mod from "../index.js"; work considering the input has no default export.
2. Why does the output adds a default export even though the input did not have one?
   • Does not this mean a user of a library may have slightly different APIs exposed if they are using the the ESM or the CJS version?

I am probably missing some basic piece of information here, any help would be appreciated 😄

Thanks.
Shahar.

Node.js: 16.13.0
npm: 8.1.3

In my package.json

"scripts": {
  ...
  "build": "gen-esm-wrapper dist/index.js dist/index.mjs",
  ...
}

and when I use command npm run build then command doesn't finished.

So I shoude be use Ctrl+C to exit command.

We're having an issue when using esbuild v0.12.7 and importing libraries that use gen-esm-wrapper:

• Chevrotain/chevrotain#1537
• jawj/zapatos#92

My initial proposal for chevrotain was to use --exclude=__esModule but I think that __esModule should probably be excluded by default in gen-esm-wrapper.

I think it would be safe to use Object.keys instead of Object.getOwnPropertyNames so we can exclude non-enumerable properties.