This is a repository used to test a new exports condition in Node.js that can be used to point to an ESM file no matter the package is loaded using import or require, so that it supports shipping patterns like this:

{
  "type": "module",
  "exports": {
    "node": {
      // On new version of Node.js, both require() and import get the ESM version
      "module": "./index.js",
      // On older version of Node.js, where "module" and require(esm) are not supported,
      // use the transpiled CJS version for require(). Library authors decide
      // to drop support for older versions of Node.js when they think it's time.
      "require": "./dist/index.cjs"
    },
    // On any other environment, or when it's imported on older version of Node.js,
    // use the ESM version.
    "default": "./index.js"
  }
}

This is taking the existing module condition already supported by bundlers. See https://gist.github.com/sokra/e032a0f17c1721c71cfced6f14516c62

Tested output

Native node

Using nodejs/node#54648

$ ../node/out/Release/node workspace/src/import.mjs
import-module-require import
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import module

$ ../node/out/Release/node --experimental-require-module workspace/src/require.cjs
import-module-require module
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import require

Webpack

The bundled version runs the same as the native version:

$ npm run webpack

$ node workspace/webpack/require.bundle.js
import-module-require module
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import require

$ node workspace/webpack/import.bundle.js
import-module-require import
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import module

esbuild

The bundled version runs the same as the native version:

$ npm run esbuild

$ node workspace/esbuild/require.bundle.js
import-module-require module
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import require

$ node workspace/esbuild/import.bundle.js
import-module-require import
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import module

Rollup

Unlike the previous two, rollup does not seem to support insertion-order priorities of module conditions, and "module" always take precedence.

$ npm run rollup

$ node workspace/rollup/require.bundle.js
import-module-require module
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import module

$ node workspace/rollup/import.bundle.js
import-module-require module
module-and-import module
module-and-require module
module-import-require module
module-only module
module-require-import module
require-module-import module