Install

# NPM
npm install --save-dev webpack-bundle-analyzer
# Yarn
yarn add -D webpack-bundle-analyzer

Usage (as a plugin)

const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;

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

It will create an interactive treemap visualization of the contents of all your bundles.

This module will help you:

1. Realize what's really inside your bundle
2. Find out what modules make up the most of its size
3. Find modules that got there by mistake
4. Optimize it!

And the best thing is it supports minified bundles! It parses them to get real size of bundled modules.And it also shows their gzipped sizes!

Options (for plugin)

new BundleAnalyzerPlugin(options?: object)

Usage (as a CLI utility)

You can analyze an existing bundle if you have a webpack stats JSON file.

You can generate it using BundleAnalyzerPlugin with generateStatsFile option set to true or with this simplecommand:

webpack --profile --json > stats.json

If you're on Windows and using PowerShell, you can generate the stats file with this command to avoid BOM issues:

webpack --profile --json | Out-file 'stats.json' -Encoding OEM

Then you can run the CLI tool.

webpack-bundle-analyzer bundle/output/path/stats.json

Options (for CLI)

webpack-bundle-analyzer <bundleStatsFile> [bundleDir] [options]

Arguments are documented below:

bundleStatsFile

Path to webpack stats JSON file

bundleDir

Directory containing all generated bundles.

options

  -V, --version               output the version number
  -m, --mode <mode>           Analyzer mode. Should be `server`, `static` or `json`.
                              In `server` mode analyzer will start HTTP server to show bundle report.
                              In `static` mode single HTML file with bundle report will be generated.
                              In `json` mode single JSON file with bundle report will be generated. (default: server)
  -h, --host <host>           Host that will be used in `server` mode to start HTTP server. (default: 127.0.0.1)
  -p, --port <n>              Port that will be used in `server` mode to start HTTP server. Should be a number or `auto` (default: 8888)
  -r, --report <file>         Path to bundle report file that will be generated in `static` mode. (default: report.html)
  -t, --title <title>         String to use in title element of html report. (default: pretty printed current date)
  -s, --default-sizes <type>  Module sizes to show in treemap by default.
                              Possible values: stat, parsed, gzip (default: parsed)
  -O, --no-open               Don't open report in default browser automatically.
  -e, --exclude <regexp>      Assets that should be excluded from the report.
                              Can be specified multiple times.
  -l, --log-level <level>     Log level.
                              Possible values: debug, info, warn, error, silent (default: info)
  -h, --help                  output usage information

Size definitions

webpack-bundle-analyzer reports three values for sizes. defaultSizes can be used to control which of these is shown by default. The different reported sizes are:

stat

This is the "input" size of your files, before any transformations likeminification.

It is called "stat size" because it's obtained from Webpack'sstats object.

parsed

This is the "output" size of your files. If you're using a Webpack plugin suchas Uglify, then this value will reflect the minified size of your code.

gzip

This is the size of running the parsed bundles/modules through gzip compression.

Selecting Which Chunks to Display

When opened, the report displays all of the Webpack chunks for your project. It's possible to filter to a more specific list of chunks by using the sidebar or the chunk context menu.

Sidebar

The Sidebar Menu can be opened by clicking the > button at the top left of the report. You can select or deselect chunks to display under the "Show chunks" heading there.

Chunk Context Menu

The Chunk Context Menu can be opened by right-clicking or Ctrl-clicking on a specific chunk in the report. It provides the following options:

• Hide chunk: Hides the selected chunk
• Hide all other chunks: Hides all chunks besides the selected one
• Show all chunks: Un-hides any hidden chunks, returning the report to its initial, unfiltered view

Troubleshooting

I don't see gzip or parsed sizes, it only shows stat size

It happens when webpack-bundle-analyzer analyzes files that don't actually exist in your file system, for example when you work with webpack-dev-server that keeps all the files in RAM. If you use webpack-bundle-analyzer as a plugin you won't get any errors, however if you run it via CLI you get the error message in terminal:

Error parsing bundle asset "your_bundle_name.bundle.js": no such file
No bundles were parsed. Analyzer will show only original module sizes from stats file.

To get more information about it you can read issue #147.

Other tools

• Statoscope - Webpack bundle analyzing tool to find out why a certain module was bundled (and more features, including interactive treemap)

Maintainers

Yuriy Grunin

Vesa Laakso

Contributing

Check out CONTRIBUTING.md for instructions on contributing ��