CHANGELOG

Change Log

This project adheres to Semantic Versioning.

13.0.3

Removed picocolors dependencies.

13.0.2

Fixed glob pattern regression.

13.0.1

Fixed publishing process.

13.0.0

Removed Node.js 20 support.
Removed tinyglobby and jiti dependencies.
Added npm provenance.

12.1.0

Added disablePlugins option (by @JPeer264).
Updated esbuild.

12.0.1

Updated css-minimizer-webpack-plugin (by @SevereCloud).

12.0.0

Moved jiti to optional dependency.
Removed chokidar dependency in favor of fs.watch.
Removed Node.js 18 support.
Updated open & esbuild dependencies.
Fixed docs (by @nlopin & @just-boris).

11.2.0

Added --config argument (by @EvgenyWas).
Added top-level await support to config (by @aryaemami59).
Added time option to config (by @EvgenyWas).
Added message option to config (by @dartess).
Updated esbuild.

11.1.6

Updated chokidar.
Updated esbuild.
Updated jiti.

11.1.5

Reduced dependencies (by @ziebam).
Updated esbuild.

11.1.4

Fixed types (by @aryaemami59).

11.1.3

Updated esbuild.
Updated CSS loaders for webpack.

11.1.2

Fixed CSS support in esbuild plugin (by @just-boris).

11.1.1

Fixed Windows support (by @aryaemami59).

11.1.0

Added TypeScript support for config (by @aryaemami59).
Fixed webpack-why regression (by @hoo00nn).

11.0.3

Fixed .mjs config support (by Arya Emami).
Updated esbuild.

11.0.2

Fixed require is not defined regression.
Updated esbuild-visualizer.

11.0.1

Updated estimo.
Updated lilconfig.

11.0

Moved to Brotli as default compression. Use gzip: true for old behavior.

10.0.3

Fixed third-party plugins support (by @JounQin).
Fixed Windows support (by @JounQin).

10.0.2

Fixed require is not defined in webpack-css (by Andrey Medvedev).
Fixed webpack config defined as function support (by @lev875).

10.0.1

Fixed imports and exports between packages.

10.0

Removed @size-limit/dual-publish plugin.
Moved projects to ESM (by @lev875).
Size Limit still can be used as CLI in CJS projects.
Updated globby dependency.

9.0

Remove Node.js 14 and 16 support.
Moved to React from CDN for time plugin (by Aakansha Doshi).

8.2.6

Fixed npm release process.

8.2.5

Fixed opening report in @size-limit/esbuild-why (by Yaroslav Chapelskyi).
Updated esbuild.

8.2.4

Fixed @size-limit/esbuild-why for multiple checks (by Homa Wong).

8.2.3

Fixed npm release process.

8.2.2

Fixed npm release process.

8.2.1

Fixed @size-limit/esbuild-why package size.

8.2

Added @size-limit/esbuild-why plugin (by Homa Wong).
Fixed peer dependency (by Sébastien Vanvelthem).

8.1.2

Fixed silent mode (by Igor Suvorov).
Updated esbuild.
Reduced dependencies.

8.1.1

Updated esbuild.

8.1

Added "*" value support to import (by @denkristoffer).

8.0.1

Fixed config and modifyEsbuildConfig options (by Angelo Ashmore).
Updated esbuild.

8.0

Removed Node.js 12 support.
Added support for third-party plugins support (by @JounQin).
Added field with limit to JSON output (by Elliot Westlake).

7.0.8

Fixed peer dependencies.

7.0.7

Fixed plugin versions in presets.

7.0.6

Added brotlied note to CLI output (by @azat-io).
Updated nanospinner.

7.0.5

Added pnpm examples to migration guide.
Fixed docs (by @azat-io).

7.0.4

Updated esbuild.
Updated nanospinner.

7.0.3

Fixed package size.

7.0.2

Fixed peer dependency ignore in @size-limit/esbuild.

7.0.1

Fixed --save-bundle arguments with @size-limit/esbuild.
Fixed ignore option with @size-limit/esbuild.
Fixed brotli option without webpack.
Fixed error messages.

7.0

Added @size-limit/esbuild plugin for better performance (by Artem Tumin).
Moved @size-limit/preset-small-lib to @size-limit/esbuild.
Moved CSS from webpack plugin to @size-limit/webpack-css (by Egor Ogarkov).
Moved --why to @size-limit/webpack-why (by Egor Ogarkov).

6.0.4

Updated dependencies.

6.0.3

Updated nanospinner.

6.0.2

Fixed Statoscope report location (by Sergey Melyukov).

6.0.1

Replaced mico-spinner to nanospinner.

6.0

Moved to webpack 5 (by Ludovico Fischer).
Moved from Webpack Bundle Analyzer to Statoscope (by Sergey Melyukov).

5.0.5

Replaced nanocolors dependency with picocolors.

5.0.4

Replaced colorette dependency with nanocolors.

5.0.3

Fixed pnpm support (by @Tomyail).

5.0.2

Fixed error message on no input files for webpack.
Fixed plugins loading from optional dependencies (by Edouard Menayde).

5.0.1

Fixed mico-spinner dependency range.

5.0

Removed Node.js 10 support.
Reduced dependencies (by Stsefanovich Kanstantsin & @enemycnt).

4.12.0

Added .size-limit.cjs config file support (by Cole Ellison).

4.11.0

Added modifyWebpackConfig option (by Lenz Weber).

4.10.3

Updated optimize-css-assets-webpack-plugin.

4.10.2

Use 1000 factor for KB and 1024 for KiB (by Matthias Kunnen).

4.10.1

Fixed output on missed file (by Viktor Pasynok).

4.10

Added --silent argument (by Viktor Pasynok).

4.9.2

Fixed plugin loading for mono repository (by John Grishin).

4.9.1

Reduced dependencies by replacing cosmiconfig to lilconfig.

4.9

Added auto --highlight-less for checks with bytes in limit.
Updated dual-publish.

4.8

Added webpack stats support in --save-bundle (by Leonard Kinday).

4.7

Added --highlight-less argument (by Victor Didenko).

4.6.2

Fixed peerDependencies resolving in import.
Fixed Node.js 15 support.

4.6.1

Fixed peerDependencies support in import.
Fixed npm 7 support.
Updated css-loader and file-loader.

4.6

Added --hide-passed argument (by Kristján Oddsson).

4.5.7

Do not show loader in JSON mode (by Billy Vong).

4.5.6

Fix “file was not found” behaviour (by Pavel Pustovalov).

4.5.5

Dropped Node.js 13.0-13.6 support because of ES modules bug in that versions.

4.5.4

Better warning on missed value in CLI argument (by Mikhail Vyrodov).

4.5.3

Fixed MaxListenersExceededWarning (by Pavel Pustovalov).
Fixed gzipped note (by Evgeniy Timokhov).

4.5.2

Replace color output library.

4.5.1

Reduce dependencies.
Improve docs (by Mikhail Bashurov).

4.5

Add --clean-dir argument.

4.4.5

Fix Windows support.

4.4.4

Fix Yarn 2 support.

4.4.3

Fix Windows support (by Anton Khlynovskiy).

4.4.2

Update nanoid.

4.4.1

Update file-loader.
Add peer dependency to dual-publish plugin.

4.4

Add --watch support (by @jayhoney).

4.3.1

Fix import option.

4.3

Add multiple files support for import option.
Add multiple files support for import option.

4.2.1

Fix dual-publish error.

4.2

Add @size-limit/dual-publish plugin.

4.1.1

Fix import option.

4.1

Add tree-shaking support with import option (by Brian Schlenker).

4.0.2

Fix gzip option plugins test.
Update ci-job-number.

4.0.1

Fix note text (by Pavel Pustovalov).

4.0

Move size-limit from dependencies to peerDependencies.

3.0.1

Add Yarn PnP and Yarn 2 support (by Pavel Pustovalov).

3.0

Drop Node.js 8 support.
Add Brotli support (by Viktor Pasynok).

2.2.4

Improve MaxListenersExceededWarning fix (by Pavel Pustovalov).

2.2.3

Fix MaxListenersExceededWarning (by Pavel Pustovalov).

2.2.2

Fix JS API.

2.2.1

Fix warning message (by Alexey Taktarov).

2.2

Add JS API.

2.1.6

Fix --why for entries with exceeded limit.
Fix --why for multiple entries.

2.1.5

Fix running time calculation on parallel tasks.
Fix CI warning text during Puppeteer error.

2.1.4

Add warning for size-limit in dependencies.

2.1.3

Fix plugin loading (by Alexandr Antonov).

2.1.2

Update dependencies.

2.1.1

Ignore non .js or .mjs files in running time.
Speed up running time calculation.

2.1

Add --debug argument.

2.0.2

Fix time limit support.

2.0.1

Fix possible webpack temporal directory name conflict.

2.0

Rewrite tool with modular architecture.

Migration:

Update size-limit to 2.x version.
Run npx size-limit.
Console will output instructions for installing necessary preset.

1.3.8

Do not download Chrome for Puppeteer if you already have desktop Chrome.

1.3.7

More accurate --why (by Anton Korzunov).
Fix ignore and peerDependencies (by Anton Korzunov).
Fix --no-gzip argument.

1.3.6

Fix package.json-less project support.
Improve error message on wrong getSize() call.
Fix JSDoc.

1.3.5

Fix CI warning text.

1.3.4

Fix CI warning style.

1.3.3

Fix ignoring scoped packages.

1.3.2

Fix support extension-less package.main (by Homa Wong).
Add warning or Circle CI.

1.3.1

Speed up running time calculation.

1.3

Add --save-bundle argument (by Ivan Solovev).

1.2

Add --json argument (by Pavel Vostrikov).

1.1.2

Fix running time calculation on webpack: false.

1.1.1

Allow to use Size Limit on CI with Node.js <8 tasks.

1.1

Calculate time to download and execute JS.
Improve CLI UI.

1.0.1

Fix Markdown files support (by Scaria Rex Arun and Kiryl Misachenka).

1.0

Add .size-limit.json config name support.

0.22

Drop Node.js 6 support.
Update inner CLI tools.

0.21.1

Use css-loader 2.0 (by Redmond Tran).
Use file-loader 3.0.

0.21

Add support for dynamic filename in custom Webpack config (by Naijia Liu).
Add entry option (by Naijia Liu).

0.20.1

Use compression-webpack-plugin 2.0.
Use webpack-bundle-analyzer 3.0.

0.20

Use package.json#main as default path for limit.
Fix custom webpack config support with resolve or resolveLoader options.

0.19.3

Update file-loader and style-loader.

0.19.2

Fix ignore option (by Jayden Seric).

0.19.1

Use style-loader 0.22.

0.19

Add ignore option to config.

0.18.5

Fix absolute path support.

0.18.4

Update dependencies.
Fix documentation.

0.18.3

Use read-pkg-up 4.x.
Remove development config from package.json.

0.18.2

Fix size with new webpack.

0.18.1

Move development config files from npm package.

0.18

Add .size-limit.js config support (by Olivier Tassinari).

0.17.1

Use cosmiconfig 5.x.
Improve CI (by Daniel Ruf).

0.17

Remove deprecated limit CLI API and add --limit argument.

0.16.2

Fix peerDependencies and --why (by Bogdan Chadkin).

0.16.1

Allow to use Size Limit in CI with Node.js 4.

0.16

getSize() now returns { gzip, parsed } (by Bogdan Chadkin).
Improve size calculation accuracy (by Bogdan Chadkin).
Array support in the path (by Bogdan Chadkin).

0.15.2

Improve performance (by Bogdan Chadkin).

0.15.1

Allow to use Size Limit in CI with Node.js 4.

0.15

Remove Node.js 4 support.
Use webpack 4.0 (by Jayden Seric).
Use globby 8.0.

0.14.1

Use cosmiconfig 4.0.
Use yargs 11.0.

0.14

Add name option to config.
Add gzip option to config.

0.13.2

Use globby 7.0.

0.13.1

Allow to use Size Limit without package.json.

0.13

Add .size-limit config support (by Vladimir Borovik).

0.12.1

Fix dependency resolving with custom webpack config (by Sivan Mehta).

0.12

Add custom webpack config support (by Sivan Mehta).

0.11.6

Fix CLI messages (by @mute).

0.11.5

Better error message on --why with "webpack": false.

0.11.4

Update yargs.

0.11.3

Better error message on wrong config.
Fix English in config error messages (by Tim Marinin).

0.11.2

Show config example in config error messages.
Better error message on wrong config.

0.11.1

Better error message on missed file in legacy CLI.

0.11

Ignore size of peerDependencies.

0.10

Add CSS files support (by Sebastian Werner).
Add support for more static files types (by Sebastian Werner).

0.9

Use UglifyJS 3 to support ES2016 out of box.
Add argument and option to disable webpack.
Deprecate argument and option for Babili.
Deprecate limit in CLI arguments.
Deprecate old "sizeLimit" section name.
Better error messages style.
Clean npm package from test files.

0.8.4

Fix error messages text (by Alexandr Subbotin).

0.8.3

Improve error messages style.

0.8.2

Better output for projects with multiple limits.
Fix multiple limits support in --why.

0.8.1

Improve CLI help (by Peter deHaan).

0.8

Add size-limit configuration section support.

0.7.1

Fix multiline error messages in CLI.
Do not load node-zopfli as loose dependency.

0.7

Add glob pattern support to sizeLimit section.

0.6.2

Better project name in Webpack Bundle Analyzer.

0.6.1

Load images by file-loader.

0.6

Add sizeLimit configuration section support.

0.5.1

Use gzip sizes in Webpack Bundle Analyzer.

0.5

Add Semaphore support.

0.4

Add CircleCI support.

0.3.2

Fix bundle name in --why mode.
Move gzip calculation inside webpack.

0.3.1

Use read-pkg-up to find package.json.
Use ci-job-number to detect CI job number.

0.3

Run only on first CI job to save CI resources.

0.2

Add --babili argument.
Use Chalk 2.

0.1.3

Fix CLI text (by Yaroslav Markin).

0.1.2

Fix CLI text (by Marais Rossouw).

0.1.1

Fix parsing B unit without kilo/mega prefix.

0.1

Initial release.

README

Size Limit

Size Limit is a performance budget tool for JavaScript. It checks every commit
on CI, calculates the real cost of your JS for end-users and throws an error
if the cost exceeds the limit.

ES modules and tree-shaking support.
Add Size Limit to GitHub Actions, Circle CI or another CI system
to know if a pull request adds a massive dependency.
Modular to fit different use cases: big JS applications
that use their own bundler or small npm libraries with many files.
Can calculate the time it would take a browser
to download and execute your JS. Time is a much more accurate
and understandable metric compared to the size in bytes.
Additionally, you can customize time plugin via config
for every check with network speed, latency and so on.
Calculations include all dependencies and polyfills
used in your JS.

With GitHub action Size Limit will post bundle size changes as a comment
in pull request discussion.

With --why, Size Limit can tell you why your library is of this size
and show the real cost of all your internal dependencies.
We are using Statoscope for this analysis.

Size Limit is built by Evil Martians, an American design and engineering consultancy for developer tools, AI, and cybersecurity startups.

Who Uses Size Limit

MobX
Material-UI
Ant Design
Autoprefixer
PostCSS reduced
25% of the size.
Browserslist reduced
25% of the size.
EmojiMart reduced
20% of the size
nanoid reduced
33% of the size.
React Focus Lock reduced
32% of the size.
Logux reduced
90% of the size.

How It Works

Size Limit contains a CLI tool, 3 plugins (file, webpack, time)
and 3 plugin presets for popular use cases (app, big-lib, small-lib).
A CLI tool finds plugins in package.json and loads the config.
If you use the webpack plugin, Size Limit will bundle your JS files into
a single file. It is important to track dependencies and webpack polyfills.
It is also useful for small libraries with many small files and without
a bundler.
The webpack plugin creates an empty webpack project, adds your library
and looks for the bundle size difference.
The time plugin compares the current machine performance with that of
a low-priced Android devices to calculate the CPU throttling rate.
Then the time plugin runs headless Chrome (or desktop Chrome if it’s
available) to track the time a browser takes to compile and execute your JS.
Note that these measurements depend on available resources and might
be unstable. See here
for more details.

Usage

JS Applications

Suitable for applications that have their own bundler and send the JS bundle
directly to a client (without publishing it to npm). Think of a user-facing app
or website, like an email client, a CRM, a landing page or a blog with
interactive elements, using React/Vue/Svelte lib or vanilla JS.

Show instructions

Install the preset:

npm install --save-dev size-limit @size-limit/file

Add the size-limit section and the size script to your package.json:

diff

+ "size-limit": [
+   {
+     "path": "dist/app-*.js"
+   }
+ ],
  "scripts": {
    "build": "webpack ./webpack.config.js",
+   "size": "npm run build && size-limit",
    "test": "vitest && eslint ."
  }

Here’s how you can get the size for your current project:

$ npm run size

  Package size: 30.08 kB with all dependencies, minified and brotlied

Now, let’s set the limit. Add 25% to the current total size and use that as
the limit in your package.json:
diff
```
"size-limit": [
    {
+     "limit": "35 kB",
      "path": "dist/app-*.js"
    }
  ],
```

Add the size script to your test suite:

diff

"scripts": {
    "build": "webpack ./webpack.config.js",
    "size": "npm run build && size-limit",
-   "test": "vitest && eslint ."
+   "test": "vitest && eslint . && npm run size"
  }

If you don’t have a continuous integration service running, don’t forget
to add one — start with GitHub Actions.

JS Application and Time-based Limit

File size limit (in kB) is not the best way to describe your JS application
cost for developers. Developers will compare the size of the JS bundle
with the size of images. But browsers need much more time to parse 100 kB
of JS than 100 kB of an image since JS compilers are very complex.

This is why Size Limit support time-based limit. It runs headless Chrome
to track the time a browser takes to compile and execute your JS.

Show instructions

Install the preset:

npm install --save-dev size-limit @size-limit/preset-app

Add the size-limit section and the size script to your package.json:

diff

+ "size-limit": [
+   {
+     "path": "dist/app-*.js"
+   }
+ ],
  "scripts": {
    "build": "webpack ./webpack.config.js",
+   "size": "npm run build && size-limit",
    "test": "vitest && eslint ."
  }

Here’s how you can get the size for your current project:

$ npm run size

  Package size: 30.08 kB with all dependencies, minified and brotlied
  Loading time: 602 ms   on slow 3G
  Running time: 214 ms   on Snapdragon 410
  Total time:   815 ms

Now, let’s set the limit. Add 25% to the current total time and use that as
the limit in your package.json:
diff
```
"size-limit": [
    {
+     "limit": "1 s",
      "path": "dist/app-*.js"
    }
  ],
```

Add the size script to your test suite:

diff

"scripts": {
    "build": "webpack ./webpack.config.js",
    "size": "npm run build && size-limit",
-   "test": "vitest && eslint ."
+   "test": "vitest && eslint . && npm run size"
  }

If you don’t have a continuous integration service running, don’t forget
to add one — start with GitHub Actions.

Big Libraries

JS libraries > 10 kB in size.

This preset includes headless Chrome, and will measure your lib’s execution
time. You likely don’t need this overhead for a small 2 kB lib, but for larger
ones the execution time is a more accurate and understandable metric that
the size in bytes. Libraries like React are good examples for this preset.

Show instructions

Install preset:

npm install --save-dev size-limit @size-limit/preset-big-lib

Add the size-limit section and the size script to your package.json:

diff

+ "size-limit": [
+   {
+     "path": "dist/react.production-*.js"
+   }
+ ],
  "scripts": {
    "build": "webpack ./scripts/rollup/build.js",
+   "size": "npm run build && size-limit",
    "test": "vitest && eslint ."
  }

If you use ES modules you can test the size after tree-shaking with import
option:

diff

"size-limit": [
    {
      "path": "dist/react.production-*.js",
+     "import": "{ createComponent }"
    }
  ],

Here’s how you can get the size for your current project:

$ npm run size

  Package size: 30.08 kB with all dependencies, minified and brotlied
  Loading time: 602 ms   on slow 3G
  Running time: 214 ms   on Snapdragon 410
  Total time:   815 ms

Now, let’s set the limit. Add 25% to the current total time and use that
as the limit in your package.json:
diff
```
"size-limit": [
    {
+     "limit": "1 s",
      "path": "dist/react.production-*.js"
    }
  ],
```

Add a size script to your test suite:

diff

"scripts": {
    "build": "rollup ./scripts/rollup/build.js",
    "size": "npm run build && size-limit",
-   "test": "vitest && eslint ."
+   "test": "vitest && eslint . && npm run size"
  }

If you don’t have a continuous integration service running, don’t forget
to add one — start with GitHub Actions.

Add the library size to docs, it will help users to choose your project:

diff

# Project Name

  Short project description

  * **Fast.** 10% faster than competitor.
+ * **Small.** 15 kB (minified and brotlied).
+   [Size Limit](https://github.com/ai/size-limit) controls the size.

Small Libraries

JS libraries < 10 kB in size.

This preset will only measure the size, without the execution time, so it’s
suitable for small libraries. If your library is larger, you likely want
the Big Libraries preset above. Nano ID or Storeon are good examples
for this preset.

Show instructions

First, install size-limit:

npm install --save-dev size-limit @size-limit/preset-small-lib

Add the size-limit section and the size script to your package.json:

diff

+ "size-limit": [
+   {
+     "path": "index.js"
+   }
+ ],
  "scripts": {
+   "size": "size-limit",
    "test": "vitest && eslint ."
  }

Here’s how you can get the size for your current project:

$ npm run size

  Package size: 177 B with all dependencies, minified and brotlied

If your project size starts to look bloated, run --why for analysis:
sh
```
npm run size -- --why
```
We use Statoscope as bundle analyzer.
Now, let’s set the limit. Determine the current size of your library,
add just a little bit (a kilobyte, maybe) and use that as the limit
in your package.json:
diff
```
"size-limit": [
    {
+     "limit": "9 kB",
      "path": "index.js"
    }
 ],
```

Add the size script to your test suite:

diff

"scripts": {
    "size": "size-limit",
-   "test": "vitest && eslint ."
+   "test": "vitest && eslint . && npm run size"
  }

If you don’t have a continuous integration service running, don’t forget
to add one — start with GitHub Actions.

Add the library size to docs, it will help users to choose your project:

diff

# Project Name

  Short project description

  * **Fast.** 10% faster than competitor.
+ * **Small.** 500 bytes (minified and brotlied). No dependencies.
+   [Size Limit](https://github.com/ai/size-limit) controls the size.

Reports

Size Limit has a GitHub action that comments and rejects pull requests based
on Size Limit output.

Install and configure Size Limit as shown above.
Add the following action inside .github/workflows/size-limit.yml

yaml

name: 'size'
on:
  pull_request:
    branches:
      - master
jobs:
  size:
    runs-on: ubuntu-latest
    env:
      CI_JOB_NUMBER: 1
    steps:
      - uses: actions/checkout@v1
      - uses: andresz1/size-limit-action@v1
        with:
          github_token: ${{ secrets.GITHUB_TOKEN }}

Config

Plugins and Presets

Plugins or plugin presets will be loaded automatically from package.json.
For example, if you want to use @size-limit/webpack, you can just use
npm install --save-dev @size-limit/webpack, or you can use our preset
@size-limit/preset-big-lib.

Plugins:

@size-limit/file checks the size of files with Brotli (default), Gzip
or without compression.
@size-limit/webpack adds your library to empty webpack project
and prepares bundle file for file plugin.
@size-limit/webpack-why adds reports for webpack plugin
about your library is of this size to show the cost of all your
dependencies.
@size-limit/webpack-css adds css support for webpack plugin.
@size-limit/esbuild is like webpack plugin, but uses esbuild
to be faster and use less space in node_modules.
@size-limit/esbuild-why add reports for esbuild plugin
about your library is of this size to show the cost of all your
dependencies.
@size-limit/time uses headless Chrome to track time to execute JS.

Plugin presets:

@size-limit/preset-app contains file and time plugins.
@size-limit/preset-big-lib contains webpack, file, and time plugins.
@size-limit/preset-small-lib contains esbuild and file plugins.

Third-Party Plugins

Third-party plugins and presets named starting with size-limit- are also supported.
For example:

size-limit-node-esbuild
is like @size-limit/esbuild but for Node libraries.
size-limit-preset-node-lib
is like @size-limit/preset-small-lib but for Node libraries which contains
above node-esbuild and core file plugins.
nx-size-limit
is an NX build system community plugin.

Limits Config

Size Limits supports three ways to define limits config.

size-limit section in package.json:

json

"size-limit": [
    {
      "path": "index.js",
      "import": "{ createStore }",
      "limit": "500 ms"
    }
  ]

or a separate .size-limit.json config file:

;[
  {
    path: 'index.js',
    import: '{ createStore }',
    limit: '500 ms'
  }
]

or a more flexible .size-limit.js or .size-limit.cjs config file:

module.exports = [
  {
    path: 'index.js',
    import: '{ createStore }',
    limit: '500 ms'
  }
]

or types .size-limit.ts:

import type { SizeLimitConfig } from '../../packages/size-limit'

module.exports = [
  {
    path: 'index.js',
    import: '{ createStore }',
    limit: '500 ms'
  }
] satisfies SizeLimitConfig

Each section in the config can have these options:

path: relative paths to files. The only mandatory option.
It could be a path "index.js", a pattern "dist/app-*.js"
or an array ["index.js", "dist/app-*.js", "!dist/app-exclude.js"].
import: partial import to test tree-shaking. It could be "{ lib }"
to test import { lib } from 'lib', * to test all exports,
or { "a.js": "{ a }", "b.js": "{ b }" } to test multiple files.
limit: size or time limit for files from the path option. It should be
a string with a number and unit, separated by a space.
Format: 100 B, 10 kB, 500 ms, 1 s.
name: the name of the current section. It will only be useful
if you have multiple sections.
message: an optional custom message to display additional information,
such as guidance for resolving errors, relevant links, or instructions
for next steps when a limit is exceeded.
entry: when using a custom webpack config, a webpack entry could be given.
It could be a string or an array of strings.
By default, the total size of all entry points will be checked.
webpack: with false it will disable webpack.
running: with false it will disable calculating running time.
gzip: with true it will use Gzip compression and disable
Brotli compression.
brotli: with false it will disable any compression.
config: a path to a custom webpack or esbuild config.
ignore: an array of files and dependencies to exclude from
the project size calculation.
modifyWebpackConfig: (.size-limit.js only) function that can be used
to do last-minute changes to the webpack config, like adding a plugin.
modifyEsbuildConfig: (.size-limit.js only) function that can be used
to do last-minute changes to the webpack config, like adding a plugin.
compareWith: path to stats.json from another build to compare
(when --why is using).
uiReports: custom UI reports list (see Statoscope docs).
disablePlugins: npm package names of plugins to skip
for this check. For example: "@size-limit/webpack", "@size-limit/esbuild",
or "@size-limit/time".

If you use Size Limit to track the size of CSS files, make sure to set
webpack: false. Otherwise, you will get wrong numbers, because webpack
inserts style-loader runtime (≈2 kB) into the bundle.

Also, you avoid having a config and pass the limit to CLI:

npm install --save-dev @size-limit/file
npx size-limit --limit "10 kB" dist/bundle.js

Additionally, you can specify a custom path to your configuration file when running the CLI:

npx size-limit --config configs/size-limit.json

Analyze with `--why`

You can run size-limit --why to analyze the bundle.

You will need to install @size-limit/esbuild-why or @size-limit/webpack-why
depends on which bundler you are using (default is esbuild).

For @size-limit/esbuild-why,
it will generate a esbuild-why.html at the current directory & open it in the browser.

If you also specify --save-bundle <DIR>,
the report will be generated inside <DIR>.

If you have multiple sections in your config,
the files will be named esbuild-why-{n}.html,
or you can give it a custom name:

jsonc

[
  {
    "name": "cjs"
    /* snap */
  },
  {
    "name": "esm"
    /* snap */
  }
]

This will produce esbuild-why-cjs.html and esbuild-why-esm.html respectively.

For @size-limit/webpack-why,
it will generate the report and open it in the browser automatically.

JS API

const sizeLimit = require('size-limit')
const filePlugin = require('@size-limit/file')
const webpackPlugin = require('@size-limit/webpack')

sizeLimit([filePlugin, webpackPlugin], [filePath]).then(result => {
  result //=> { size: 12480 }
})

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13.0.3

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