webpack-bundle-analyzer-react-scripts-2&3.js

// script to enable webpack-bundle-analyzer
process.env.NODE_ENV = 'production';
const webpack = require('webpack');
const BundleAnalyzerPlugin = require('webpack-bundle-analyzer')
  .BundleAnalyzerPlugin;
const webpackConfigProd = require('react-scripts/config/webpack.config')('production');

webpackConfigProd.plugins.push(new BundleAnalyzerPlugin());

// actually running compilation and waiting for plugin to start explorer
webpack(webpackConfigProd, (err, stats) => {
  if (err || stats.hasErrors()) {
    console.error(err);
  }
});