Demos: Bundle analysis comparison · Bundle analysis

BundleStats webpack plugin

Analyze bundle stats(bundle size, assets, modules, packages) and compare the results between different builds. Support for webpack, rspack, vite, rollup and rolldown.

- Bundle size and totals by file type(css, js, img, etc)
- Insights: duplicate packages, new packages
- Initial JS/CSS, Cache invalidation, and other bundle metrics
- Assets report (entrypoint, initial, types, changed, delta)
- Modules report (changed, delta, chunks, duplicate count and percentage)
- Packages report (count, duplicate, changed, delta)
⭐ Side by side comparison for multiple builds

Table of Contents

• Install
• Webpack configuration
  • BundleStatsWebpackPlugin(options)
  • Use with create-react-app
• Compare mode
• Other packages
• Related projects

Install

npm install --dev bundle-stats-webpack-plugin

or

yarn add --dev bundle-stats-webpack-plugin

Webpack configuration

// webpack.config.js
const { BundleStatsWebpackPlugin } = require('bundle-stats-webpack-plugin');

module.exports = {
  ...,
  plugins: [
    new BundleStatsWebpackPlugin()
  ]
}

BundleStatsWebpackPlugin(options)

• compare - use local saved baseline for comparison (default true).
• baseline - save current webpack stats as baseline (default false).
• html - output html report (default true).
• json - output json report (default false).
• outDir - output directory relative to webpack output.path (default '').
• baselineFilepath - baseline filepath relative to webpack output.path (default 'node_modules/.cache/bundle-stats/baseline.json')
• silent - stop logging info and only log warning and error (default false).
• stats - Webpack stats options default:

  // webpack.config.js
  module.exports = {
    // ...
    stats: {
      assets: true,
      chunks: true,
      modules: true,
      builtAt: true,
      hash: true,
    },
  };

How to configure webpack for better debugging and monitoring

How to exclude virtual modules

Some plugins use virtual modules as an intermediary step when generating JS modules. For example, vanilla-extract creates a virtual module for every .css.js/css.ts file based on the loader module path and the filename/source as query parameters:

./node_modules/@vanilla-extract/webpack-plugin/vanilla.virtual.css?%7B%22fileName%22%3A%22src%2Fcomponents%2Fcomponent%2Fcomponent.css.ts.vanilla.css%22%2C%22source%22%3A%22...%22%7D

Inlining the encoded source and the filename causes an increase in the size of the output stats and adds unnecessary entries to the stats. To ignore vanilla-extract virtual modules from the stats and from the bundle analysis report, use excludeModules option:

// webpack.config.js
module.exports = {
  // ...
  stats: {
    excludeModules: [
      /@vanilla-extract\/webpack-plugin\/vanilla-virtual\.css/,
    ],
  },
};

Use with create-react-app

You will need to customize the default webpack config. That can be done by using react-app-rewired which is one of create-react-app's custom config solutions. You will also need customize-cra.

npm install --dev customize-cra react-app-rewired

or

yarn add customize-cra react-app-rewired --dev

Change your default scripts in package.json to:

/* package.json */
"scripts": {
  "start": "react-app-rewired start",
  "build": "react-app-rewired build",
  "test": "react-app-rewired test"
}

Create a file config-overrides.js at the same level as package.json.

// config-overrides.js
const { override, addWebpackPlugin } = require('customize-cra');
const { BundleStatsWebpackPlugin } = require('bundle-stats-webpack-plugin');

module.exports = override(
  addWebpackPlugin(new BundleStatsWebpackPlugin()),
);

Compare mode

In compare mode, the metrics are compared against an existing(node_modules/.cache/bundle-stats/baseline.json) Webpack stats file(baseline). To generate the baseline webpack stats, set BUNDLE_STATS_BASELINE environmental variable to true or set BundleStatsWebpackPlugin baseline option to true:

# Checkout to the branch/tag/commit where you want to generate the baseline
$ git checkout master

# Build your application with BUNDLE_STATS_BASELINE environmental variable
$ BUNDLE_STATS_BASELINE=true npm run build

# Checkout to the working branch/tag/commit
$ git checkout MY_FEATURE_BRANCH

# Build your application
$ npm run build

The option can be disabled by setting BundleStatsWebpackPlugin compare option to false.

Other packages

bundle-stats

CLI to generate bundle stats report.

gatsby-plugin-bundle-stats

Gatsby plugin for bundle-stats.

next-plugin-bundle-stats

Next.js plugin for bundle-stats.

rollup-plugin-bundle-stats

Rollup plugin to generate bundle stats report for vite/rolldown/rollup.

Related projects

🌀 relative-ci.com

Optimize your web app's performance with automated bundle stats analysis and monitoring.

• 🔮 In-depth bundle stats analysis for every build
• 📈 Monitor bundle stats changes and identify opportunities for optimizations
• 🔔 Rule based automated review flow, or get notified via GitHub Pull Request comments, GitHub check reports and Slack messages
• 🔧 Support for webpack and beta support for Vite/Rollup
• 🔨 Support for all major CI services(CircleCI, GitHub Actions, Gitlab CI, Jenkins, Travis CI)
• 🔩 Support for npm, yarn and pnpm; support for monorepos
• 💕 Always free for Open Source

🚀 Get started

🌓 relative-ci/compare

Standalone web application to compare Webpack/Lighthouse/Browsertime stats.

Compare bundle stats

⚡ bundle-stats-action

Github Action that generates bundle-stats reports.