webpack.config.build.js

const webpack = require('webpack');
const merge = require('webpack-merge');
const common = require('./webpack.config.common');

module.exports = merge(common, {
  mode: 'production',
  externals: [
    {
      react: {
        root: 'React',
        commonjs2: 'react',
        commonjs: 'react',
        amd: 'react',
      },
      'react-dom': {
        root: 'ReactDOM',
        commonjs2: 'react-dom',
        commonjs: 'react-dom',
        amd: 'react-dom',
      },
      lodash: {
        commonjs: 'lodash',
        commonjs2: 'lodash',
        amd: 'lodash',
        root: '_',
      },
    },
    '@material-ui/core',
    /@material-ui\/core\/*./,
    'clsx',
  ],
  plugins: [
    new webpack.DefinePlugin({
      'process.env': {
        NODE_ENV: JSON.stringify('production'),
      },
      __DEV__: false,
    }),
  ],
});