rollup-plugin-webpack-stats

rollup-plugin-webpack-stats

Rollup/Vite/Rolldown plugin to generate a stats JSON file with a bundle-stats webpack-compatible structure.

This plugin generates a webpack-compatible stats JSON file for programmatic usage, inspection, or integration with other compatible tools. To analyze your Rollup/Vite/Rolldown bundle, use rollup-plugin-bundle-stats instead.

Install

npm install --dev rollup-plugin-webpack-stats

or

yarn add --dev rollup-plugin-webpack-stats

or

pnpm add -D rollup-plugin-webpack-stats

Configure

// rollup.config.js
import webpackStatsPlugin from 'rollup-plugin-webpack-stats';

export default {
  plugins: [
    // add it as the last plugin
    webpackStatsPlugin(),
  ],
};

// vite.config.js
import { defineConfig } from 'vite';
import webpackStatsPlugin from 'rollup-plugin-webpack-stats';

export default defineConfig((env) => ({
  plugins: [
    // Output webpack-stats.json file
    webpackStatsPlugin(),
  ],
}));

Options

• fileName - the JSON filepath relative to the build folder or absolute(default: webpack-stats.json)
• transform - access and mutate the resulting stats after the conversion: (stats: WebpackStatsFilterd, sources: TransformSources, bundle: OutputBundle) => WebpackStatsFilterd
• moduleOriginalSize - extract module original size or rendered size (default: false)
• write - format and write the stats to disk(default: fs.write(filename, JSON.stringify(stats, null, 2)))
• rollup stats options (rollup-plugin-stats)
  • excludeAssets - exclude matching assets: string | RegExp | ((filepath: string) => boolean) | Array<string | RegExp | ((filepath: string) => boolean)>
  • excludeModules - exclude matching modules: string | RegExp | ((filepath: string) => boolean) | Array<string | RegExp | ((filepath: string) => boolean)>

Examples

Output to a custom filename

// rollup.config.js
import webpackStatsPlugin from 'rollup-plugin-webpack-stats';

module.exports = {
  plugins: [
    // add it as the last plugin
    webpackStatsPlugin({
      filename: 'artifacts/stats.json',
    }),
  ],
};

Exclude .map files

// rollup.config.js
import webpackStatsPlugin from 'rollup-plugin-webpack-stats';

export default {
  plugins: [
    // add it as the last plugin
    webpackStatsPlugin({
      excludeAssets: /\.map$/,
    }),
  ],
};

Vite.js - multiple stats files when using plugin-legacy

// for the the modern and legacy outputs
import { defineConfig } from 'vite';
import legacy from '@vitejs/plugin-legacy';
import webpackStatsPlugin from 'rollup-plugin-webpack-stats';

export default defineConfig((env) => ({
  build: {
    rollupOptions: {
      output: {
        plugins: [
          // Output webpack-stats-modern.json file for the modern build
          // Output webpack-stats-legacy.json file for the legacy build
          // Stats are an output plugin, as plugin-legacy works by injecting
          // an additional output, that duplicates the plugins configured here
          webpackStatsPlugin((options) => {
            const isLegacy = options.format === 'system';
            return {
              fileName: `webpack-stats${isLegacy ? '-legacy' : '-modern'}.json`,
            };
          }),
        ],
      },
    },
  },
  plugins: [
    legacy({
      /* Your legacy config here */
    }),
  ],
}));

Vite.js - update initial flag for chunks where the inital flag is incorrectly set to false

import { defineConfig } from 'vite';
import webpackStatsPlugin from 'rollup-plugin-webpack-stats';

export default defineConfig((env) => ({
  build: {
    rollupOptions: {
      output: {
        plugins: [
          webpackStatsPlugin({
            transform: (stats) => {
              // Find the target chunk entry
              const mainChunkIndex = stats.chunks?.findIndex((chunk) =>
                chunk.names?.includes('main')
              );

              // When the tartget chunk is found, set the initial flag to true
              if (
                typeof mainChunkIndex !== 'undefined' &&
                stats?.chunks?.[mainChunkIndex]
              ) {
                stats.chunks[mainChunkIndex] = {
                  ...stats.chunks[mainChunkIndex],
                  initial: true,
                };
              }

              // return the modified stats object
              return stats;
            },
          }),
        ],
      },
    },
  },
}));

Resources

• Vite - Using plugins
• Rollup - Using plugins
• RelativeCI - Vite configuration for better bundle monitoring

@relative-ci/agent examples

• example-vite-github-action
• example-vite-cli-github-action

Related projects

bundle-stats

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

rollup-plugin-stats

Output vite/rollup/rolldown stats.

relative-ci.com

Automated bundle analysis, reviews and monitoring - Quickly identify and fix bundle regressions before shipping to production.

• In-depth bundle stats analysis for every build
• Monitor bundle stats changes and identify opportunities for optimizations
• Quick feedback with rule based automated review flow, GitHub Pull Request comments, GitHub check reports, or Slack messages
• Support for webpack, vite, rspack, rollup, rolldown
• 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

Development

Use the project node version

nvm use

Install dependencies

npm install

Prepare

npm run prepare