es module bundling with babel

.babelrc

{
    "presets": [
        ["env", { "modules": false }]
    ],

    "env": {
        "es": {},
        "lib": {
            "plugins": [
                "transform-es2015-modules-commonjs"
            ]
        }
    }
}

package.json

{
  "name": "es-module-bundling-demo",
  "version": "1.0.0",
  "description": " es module bundling with babel",
  "main": "lib/index.js",
  "module": "es/index.js",
  "jsnext:main": "es/index.js",
  "scripts": {
    "build": "npm run build:lib && npm run build:es",
    "build:lib": "BABEL_ENV=lib babel ./src --out-dir ./lib",
    "build:es": "BABEL_ENV=es babel ./src --out-dir ./es"
  },
  "dependencies": {},
  "devDependencies": {
    "babel-cli": "^6.24.0",
    "babel-core": "^6.24.0",
    "babel-preset-env": "^1.2.2"
  }
}

src-hello_word.js

// Located in src directory

function helloWorld() {
    console.log('Hello World!');
}

export default helloWorld();

src-index.js

// Located in src directory

export helloWorld from './hello_world';