next-plugin-bundle-stats/index.js

In-depth bundle analyzer for webpack(bundle size, assets, modules)

const { BundleStatsWebpackPlugin } = require('bundle-stats-webpack-plugin');

module.exports = (pluginOptions = {}) => (nextConfig = {}) => ({
  ...nextConfig,
  webpack(config, options) {
    if (!options.defaultLoaders) {
      throw new Error(
        'This plugin is not compatible with Next.js versions below 5.0.0 https://err.sh/next-plugins/upgrade',
      );
    }

    const { dev, isServer } = options;

    if (!dev && !isServer) {
      config.plugins.push(
        new BundleStatsWebpackPlugin(pluginOptions),
      );
    }

    if (typeof nextConfig.webpack === 'function') {
      return nextConfig.webpack(config, options);
    }

    return config;
  },
});