babel.config.js

// * Every now and then, we adopt best practices from CRA
// * https://tinyurl.com/yakv4ggx

// ? https://nodejs.org/en/about/releases
const NODE_OLDEST_LTS = '10.13.0';

module.exports = {
  parserOpts: { strictMode: true },
  plugins: ['@babel/plugin-proposal-export-default-from'],
  env: {
    // * Used by Jest and `npm test`
    test: {
      sourceMaps: 'both',
      presets: [
        ['@babel/preset-env', { targets: { node: true } }],
        ['@babel/preset-typescript', { allowDeclareFields: true }]
        // ? We don't care about minification
      ]
    },
    // * Used by `npm run build`
    production: {
      presets: [
        [
          '@babel/preset-env',
          {
            // ? https://github.com/babel/babel-loader/issues/521#issuecomment-441466991
            //modules: false,
            // ? https://nodejs.org/en/about/releases
            targets: { node: NODE_OLDEST_LTS }
          }
        ],
        ['@babel/preset-typescript', { allowDeclareFields: true }]
        // ? Webpack will handle minification
      ]
    }
  }
};