babel.config.js

function isWebTarget(caller) {
  return Boolean(caller && caller.target === 'web');
}

function isWebpack(caller) {
  return Boolean(caller && caller.name === 'babel-loader');
}

module.exports = api => {
  const web = api.caller(isWebTarget);
  const webpack = api.caller(isWebpack);

  return {
    presets: [
      [
        '@babel/preset-env',
        {
          useBuiltIns: web ? 'usage' : undefined,
          corejs: web ? 3 : false,
          targets: !web ? { node: 'current' } : undefined,
          modules: webpack ? false : 'commonjs',
        },
      ],
      '@babel/preset-react',
      '@babel/preset-typescript',
    ],
    plugins: [
      '@babel/plugin-proposal-class-properties',
      '@babel/plugin-proposal-export-default-from',
      '@babel/plugin-proposal-object-rest-spread',
      '@babel/plugin-proposal-optional-chaining',
      '@babel/plugin-proposal-private-methods',
    ],
    sourceType: 'unambiguous',
  };
};