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 supported browsers list between different front-end tools. It is used in:

• Autoprefixer
• babel-env-preset (no config support, only tool option)
• eslint-plugin-compat
• stylelint-no-unsupported-browser-features
• postcss-normalize

All tools that rely on Browserslist will find its config automatically, when you add the following to package.json:

{
  "browserslist": [
    "> 1%",
    "last 2 versions"
  ]
}

Or in .browserslistrc config:

# Browsers that we support

> 1%
Last 2 versions
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.

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.
6. If the above methods did not produce a valid result Browserslist will use defaults: > 1%, last 2 versions, Firefox ESR.

We recommend to write queries in package.json.

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

• last 2 versions: the last 2 versions for each browser.
• last 2 Chrome versions: the last 2 versions of Chrome browser.
• > 5% or >= 5%: versions selected by global usage statistics.
• > 5% in US: uses USA usage statistics. It accepts two-letter country code.
• > 5% in my stats: uses custom usage data.
• ie 6-8: selects an inclusive range of versions.
• Firefox > 20: versions of Firefox newer than 20.
• Firefox >= 20: versions of Firefox newer than or equal to 20.
• Firefox < 20: versions of Firefox less than 20.
• Firefox <= 20: versions of Firefox less than or equal to 20.
• Firefox ESR: the latest [Firefox ESR] version.
• iOS 7: the iOS browser version 7 directly.
• not ie <= 8: exclude browsers selected before by previous queries. You can add not to any query.

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.
• 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.

Electron

electron-to-chromium could return a compatible Browserslist query for your (major) Electron version:

const e2c = require('electron-to-chromium')
autoprefixer({
    browsers: e2c.electronToBrowserList('1.4') //=> "Chrome >= 53"
})

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%",
    "last 2 versions"
  ]
}

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%
Last 2 versions
IE 8 # 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.

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 development queries and then use defaults.

In package.json:

{
  …
  "browserslist": {
    "production": [
      "last 2 version",
      "ie 9"
    ],
    "development": [
      "last 1 version"
    ]
  }
}

In .browserslistrc config:

[production]
last 2 version
ie 9

[development]
last 1 version

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
  

Custom Usage Data

If you have a website, you can query against the usage statistics of your site:

1. Import your Google Analytics data into Can I Use. Press Import… button in Settings page.

2. Open browser DevTools on Can I Use and paste this snippet into the browser console:

   var e=document.createElement('a');e.setAttribute('href', 'data:text/plain;charset=utf-8,'+encodeURIComponent(JSON.stringify(JSON.parse(localStorage['usage-data-by-id'])[localStorage['config-primary_usage']])));e.setAttribute('download','stats.json');document.body.appendChild(e);e.click();document.body.removeChild(e);
   

3. Save the data to a browserslist-stats.json file in your project.

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 "> 5%, last 1 version" or an array ['> 5%', 'last 1 version'].

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.

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

browserslist "> 1%, last 2 versions"

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

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

Internal caches

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.