babel.js

const babelrc = (env = null) => {
  const isProd = env === 'production'
  return {
    babelrc: false,
    presets: [
      [
        'babel-preset-env',
        {
          loose: true,
          uglify: true,
          modules: false, 
          targets: {
            browsers: ['> 1%', 'last 2 versions', 'IE >= 9']
          },
          exclude: ['transform-regenerator', 'transform-es2015-typeof-symbol']
        }
      ],
      'stage-0'
    ],
    plugins: [
      'babel-plugin-transform-object-assign',
      'babel-plugin-transform-decorators-legacy',
      isProd
        ? 'babel-plugin-transform-react-remove-prop-types'
        : null,
      ['babel-plugin-transform-react-jsx', { pragma: 'h' }]
    ].filter(Boolean)
  };
};

module.exports = babelrc;