.babelrc.js

module.exports = {
  presets: [
    [
      '@babel/preset-env',
      {
        modules: false,
      },
    ],
    '@babel/preset-react',
  ],
  plugins: [
    'babel-plugin-optimize-clsx',
    [
      '@babel/plugin-proposal-class-properties',
      {
        loose: true,
      },
    ],
    [
      '@babel/plugin-proposal-object-rest-spread',
      {
        loose: true,
      },
    ],
    // any package needs to declare 7.4.4 as a runtime dependency. default is ^7.0.0
    [
      '@babel/plugin-transform-runtime',
      {
        version: '^7.4.4',
      },
    ],
    // for IE 11 support
    '@babel/plugin-transform-object-assign',
    // material-ui 'productionPlugins'
    '@babel/plugin-transform-react-constant-elements',
    'babel-plugin-transform-dev-warning',
    [
      'babel-plugin-transform-react-remove-prop-types',
      {
        mode: 'unsafe-wrap',
      },
    ],
    // END material-ui 'productionPlugins'
  ],
  ignore: [/@babel[\\|/]runtime/], // Fix a Windows issue.
};