.babelrc

{
  // standard presets applying various plugins
  presets: [
    "env",  // babel-preset-env:   supporting es2015, es2016, and es2017 (with configuration)
    "react" // babel-preset-react: react and jsx
  ],

  // explicit plugins NOT part of the presets (above) ... prefer this over yearly presets
  plugins: [
    "transform-object-rest-spread", // "object rest properties" (es2018 Stage 4)
                                    // ... ex: myFn({p1, p2, ...restParms})
  ],

  // additional plugins explicitly called out via the BABEL_ENV variable
  // ... see: build scripts in package.json
  env: {
    // BABEL_ENV=commonjs ... our CommonJS distribution (promoted in lib/ directory)
    commonjs: {
      plugins: [
        ["transform-es2015-modules-commonjs", { loose: true }]
      ]
    },
    // BABEL_ENV=es ... for our ES distribution (promoted in lib/ directory)
    es: {
      plugins: [
      ]
    },
  }
}