analyzeBundle.js

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");

// this one is optional, just for better feedback on build
const chalk = require("chalk");
const ProgressBarPlugin = require("progress-bar-webpack-plugin");
const green = (text) => {
	return chalk.green.bold(text);
};

// pushing BundleAnalyzerPlugin to plugins array
webpackConfigProd.plugins.push(new BundleAnalyzerPlugin());

// optional - pushing progress-bar plugin for better feedback;
// it can and will work without progress-bar,
// but during build time you will not see any messages for 10-60 seconds (depends on the size of the project)
// and decide that compilation is kind of hang up on you; progress bar shows nice progression of webpack compilation
webpackConfigProd.plugins.push(
	new ProgressBarPlugin({
		format: `${green("analyzing...")} ${green("[:bar]")}${green("[:percent]")}${green(
			"[:elapsed seconds]"
		)} - :msg`,
	})
);

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