browserslist

What is browserslist?

The browserslist npm package is used to share target browsers and Node.js versions between different front-end tools, like Autoprefixer, Babel, and others. It utilizes a configuration file or package.json entries to specify the range of browser versions that your project supports. It helps in making decisions for transpiling JavaScript, adding vendor prefixes to CSS, and even defining which browser versions to test during the development process.

What are browserslist's main functionalities?

Defining target browsers

This feature allows you to define a range of browsers your project supports by specifying queries like market share, last versions, or excluding certain browsers. The code sample would typically be placed in a package.json file.

"browserslist": ["> 1%", "last 2 versions", "not dead"]

Integration with build tools

Browserslist can be integrated with build tools like Webpack, Babel, or PostCSS to automatically apply browser-specific transformations based on the defined browser support criteria.

const browserslist = require('browserslist');
const supportedBrowsers = browserslist('> 0.5%, last 2 versions, Firefox ESR, not dead');

CLI Usage

Browserslist provides a command-line interface (CLI) that can be used to check which browsers and versions are selected by your queries.

npx browserslist "> 1%, last 2 versions"

Configuring environments

You can define different sets of browsers for various environments, like production or development, within a .browserslistrc file.

[production]
> 1% in US
[development]
last 1 chrome version

Other packages similar to browserslist

caniuse-api

The caniuse-api provides raw browser support data from Can I Use, which is similar to the data that browserslist uses. However, it focuses more on querying specific features for browser support rather than defining a list of supported browsers for a project.

autoprefixer

Autoprefixer is a CSS post-processor that uses browserslist to add vendor prefixes to CSS rules. It is a consumer of browserslist data rather than a direct alternative, but it serves a similar purpose in terms of browser compatibility.

@babel/preset-env

Babel's preset-env is a smart preset that allows you to use the latest JavaScript without needing to micromanage which syntax transforms are needed by your target environment. It uses browserslist to determine which features need to be transformed or polyfilled. While not a direct alternative, it shares the goal of adapting code to be compatible with different environments.

README

Browserslist

Library to share target browsers between different front-end tools. It is used in:

• Autoprefixer
• Babel (external config in package.json or browserslist will be supported in 7.0)
• postcss-preset-env
• eslint-plugin-compat
• stylelint-no-unsupported-browser-features
• postcss-normalize

Browserslist Example shows how every tool uses Browserslist. All tools will find target browsers automatically, when you add the following to package.json:

{
  "browserslist": [
    "> 1%",
    "IE 10"
  ]
}

Or in .browserslistrc config:

# Browsers that we support

> 1%
IE 10 # sorry

Developers set browsers list in queries like last 2 version to be free from updating browser versions manually. Browserslist will use Can I Use data for this queries.

Browserslist will take browsers queries from tool option, browserslist config, .browserslistrc config, browserslist section in package.json or environment variables.

You can test Browserslist queries in online demo.

Tools

• browserslist-ga downloads your website browsers statistics to use it in > 0.5% in my stats query.
• browserslist-useragent checks browser by user agent string to match Browserslist target browsers query.
• browserslist-useragent-ruby is a Ruby library to checks browser by user agent string to match Browserslist.
• caniuse-api returns browsers which support some specific feature.
• Run npx browserslist in your project directory to see project’s target browsers. This CLI tool is built-in and available in any project with Autoprefixer.

Queries

Browserslist will use browsers query from one of this sources:

1. Tool options. For example browsers option in Autoprefixer.
2. BROWSERSLIST environment variable.
3. browserslist config file in current or parent directories.
4. .browserslistrc config file in current or parent directories.
5. browserslist key in package.json file in current or parent directories. We recommend this way.
6. If the above methods did not produce a valid result Browserslist will use defaults: > 0.5%, last 2 versions, Firefox ESR, not dead.

Best Practices

• Select browsers directly (last 2 Chrome versions) only if you are making web app for kiosk with one browser. There are a lot browsers on the market. If you are making general web app you should respect browsers diversity.
• If you want to change the default set of browsers we recommend to combine last 1 version, not dead with > 0.2% (or > 1% in US, > 1% in my stats). Just last n versions adds to many dead browsers and do not add popular old versions. Just > 0.2% make popular browsers even more popular, so we will have a monopoly and stagnation, as we had with Internet Explorer 6.
• Don’t remove browsers just because you don’t know them. Opera Mini has 100 million users in Africa and it is more popular in global market, than Microsoft Edge. Chinese QQ Browsers has more market share than Firefox and desktop Safari altogether.

Full List

You can specify the versions by queries (case insensitive):

• > 5%: versions selected by global usage statistics. >=, < and <= work too.
• > 5% in US: uses USA usage statistics. It accepts two-letter country code.
• > 5% in alt-AS: uses Asia region usage statistics. List of all region codes can be found at caniuse-lite/data/regions.
• > 5% in my stats: uses custom usage data.
• cover 99.5%: most popular browsers that provide coverage.
• cover 99.5% in US: same as above, with two-letter country code.
• cover 99.5% in my stats: uses custom usage data.
• extends browserslist-config-mycompany: take queries from browserslist-config-mycompany npm package.
• ie 6-8: selects an inclusive range of versions.
• Firefox > 20: versions of Firefox newer than 20. >=, < and <= work too.
• iOS 7: the iOS browser version 7 directly.
• Firefox ESR: the latest [Firefox ESR] version.
• unreleased versions or unreleased Chrome versions: alpha and beta versions.
• last 2 major versions or last 2 iOS major versions: all minor/patch releases of last 2 major versions.
• since 2015 or last 2 years: all versions released since year 2015 (also since 2015-03 and since 2015-03-10).
• dead: browsers from last 2 version query, but with less than 0.5% in global usage statistics and without official support or updates for 24 months. Right now it is IE 10, IE_Mob 10, BlackBerry 10, BlackBerry 7, and OperaMobile 12.1.
• last 2 versions: the last 2 versions for each browser.
• last 2 Chrome versions: the last 2 versions of Chrome browser.
• defaults: Browserslist’s default browsers (> 0.5%, last 2 versions, Firefox ESR, not dead).
• not ie <= 8: exclude browsers selected by previous queries.

You can add not to any query.

Debug

Run npx browserslist in project directory to see what browsers was selected by your queries.

$ npx browserslist
and_chr 61
and_ff 56
and_qq 1.2
and_uc 11.4
android 56
baidu 7.12
bb 10
chrome 62
edge 16
firefox 56
ios_saf 11
opera 48
safari 11
samsung 5

Notes

Browserslist works with separated versions of browsers. You should avoid queries like Firefox > 0.

Multiple criteria are combined as a boolean OR. A browser version must match at least one of the criteria to be selected.

All queries are based on the Can I Use support table, e.g. last 3 iOS versions might select 8.4, 9.2, 9.3 (mixed major and minor), whereas last 3 Chrome versions might select 50, 49, 48 (major only).

Browsers

Names are case insensitive:

• Android for Android WebView.
• Baidu for Baidu Browser.
• BlackBerry or bb for Blackberry browser.
• Chrome for Google Chrome.
• ChromeAndroid or and_chr for Chrome for Android
• Edge for Microsoft Edge.
• Electron for Electron framework. It will be converted to Chrome version.
• Explorer or ie for Internet Explorer.
• ExplorerMobile or ie_mob for Internet Explorer Mobile.
• Firefox or ff for Mozilla Firefox.
• FirefoxAndroid or and_ff for Firefox for Android.
• iOS or ios_saf for iOS Safari.
• Opera for Opera.
• OperaMini or op_mini for Opera Mini.
• OperaMobile or op_mob for Opera Mobile.
• QQAndroid or and_qq for QQ Browser for Android.
• Safari for desktop Safari.
• Samsung for Samsung Internet.
• UCAndroid or and_uc for UC Browser for Android.

package.json

If you want to reduce config files in project root, you can specify browsers in package.json with browserslist key:

{
  "private": true,
  "dependencies": {
    "autoprefixer": "^6.5.4"
  },
  "browserslist": [
    "> 1%",
    "IE 10"
  ]
}

Config File

Browserslist config should be named .browserslistrc or browserslist and have browsers queries split by a new line. Comments starts with # symbol:

# Browsers that we support

> 1%
IE 10 # sorry

Browserslist will check config in every directory in path. So, if tool process app/styles/main.css, you can put config to root, app/ or app/styles.

You can specify direct path in BROWSERSLIST_CONFIG environment variables.

Shareable Configs

You can use the following query to reference an exported Browserslist config from another package:

  "browserslist": [
    "extends browserslist-config-mycompany"
  ]

For security reasons, external configuration only supports packages that have the browserslist-config- prefix. npm scoped packages are also supported, by naming or prefixing the module with @scope/browserslist-config, such as @scope/browserslist-config or @scope/browserslist-config-mycompany.

If you don’t accept Browserslist queries from users, you can disable the validation by using the dangerousExtend option:

browserslist(queries, { path, dangerousExtend: true })

Because this uses npm's resolution, you can also reference specific files in a package:

  "browserslist": [
    "extends browserslist-config-mycompany/desktop",
    "extends browserslist-config-mycompany/mobile"
  ]

When writing a shared Browserslist package, just export an array. browserslist-config-mycompany/index.js:

module.exports = [
  '> 1%',
  'ie 10'
]

Environment Variables

If some tool use Browserslist inside, you can change browsers settings by environment variables:

• BROWSERSLIST with browsers queries.

  BROWSERSLIST="> 5%" gulp css
  

• BROWSERSLIST_CONFIG with path to config file.

  BROWSERSLIST_CONFIG=./config/browserslist gulp css
  

• BROWSERSLIST_ENV with environments string.

  BROWSERSLIST_ENV="development" gulp css
  

• BROWSERSLIST_STATS with path to the custom usage data for > 1% in my stats query.

  BROWSERSLIST_STATS=./config/usage_data.json gulp css
  

• BROWSERSLIST_DISABLE_CACHE if you want to disable config reading cache.

  BROWSERSLIST_DISABLE_CACHE=1 gulp css
  

Environments

You can also specify different browser queries for various environments. Browserslist will choose query according to BROWSERSLIST_ENV or NODE_ENV variables. If none of them is declared, Browserslist will firstly look for production queries and then use defaults.

In package.json:

  "browserslist": {
    "production": [
      "> 1%",
      "ie 10"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version"
    ]
  }

In .browserslistrc config:

[production staging]
> 1%
ie 10

[development]
last 1 chrome version
last 1 firefox version

Custom Usage Data

If you have a website, you can query against the usage statistics of your site. browserslist-ga will ask access to Google Analytics and then generate browserslist-stats.json:

npx browserslist-ga

Of course, you can generate usage statistics file by any other method. File format should be like:

{
  "ie": {
    "6": 0.01,
    "7": 0.4,
    "8": 1.5
  },
  "chrome": {
    …
  },
  …
}

Note that you can query against your custom usage data while also querying against global or regional data. For example, the query > 1% in my stats, > 5% in US, 10% is permitted.

JS API

var browserslist = require('browserslist');

// Your CSS/JS build tool code
var process = function (source, opts) {
    var browsers = browserslist(opts.browsers, {
        stats: opts.stats,
        path:  opts.file,
        env:   opts.env
    });
    // Your code to add features for selected browsers
}

Queries can be a string "> 1%, IE 10" or an array ['> 1%', 'IE 10'].

If a query is missing, Browserslist will look for a config file. You can provide a path option (that can be a file) to find the config file relatively to it.

Options:

• path: file or a directory path to look for config file. Default is ..
• env: what environment section use from config. Default is production.
• stats: custom usage statistics data.
• config: path to config if you want to set it manually.
• ignoreUnknownVersions: do not throw on direct query (like ie 12). Default is false.
• dangerousExtend: Disable security checks for extend query. Default is false.

For non-JS environment and debug purpose you can use CLI tool:

browserslist "> 1%, IE 10"

Coverage

You can get total users coverage for selected browsers by JS API:

browserslist.coverage(browserslist('> 1%'))
//=> 81.4

browserslist.coverage(browserslist('> 1% in US'), 'US')
//=> 83.1

browserslist.coverage(browserslist('> 1% in my stats'), 'my stats')
//=> 83.1

browserslist.coverage(browserslist('> 1% in my stats', { stats }), stats)
//=> 82.2

Or by CLI:

$ browserslist --coverage "> 1%"
These browsers account for 81.4% of all users globally

$ browserslist --coverage=US "> 1% in US"
These browsers account for 83.1% of all users in the US

$ browserslist --coverage "> 1% in my stats"
These browsers account for 83.1% of all users in custom statistics

$ browserslist --coverage "> 1% in my stats" --stats=./stats.json
These browsers account for 83.1% of all users in custom statistics

Cache

Browserslist caches the configuration it reads from package.json and browserslist files, as well as knowledge about the existence of files, for the duration of the hosting process.

To clear these caches, use:

browserslist.clearCaches();

To disable the caching altogether, set the BROWSERSLIST_DISABLE_CACHE environment variable.

Changelog

3.2.8

• Add IE 9-5.5 to dead browsers.
• Remove development configs from npm package.