baseline-browser-mapping

By the W3C WebDX Community Group and contributors.

baseline-browser-mapping provides:

- An Array of browsers compatible with Baseline Widely available and Baseline year feature sets via the getCompatibleVersions() function.
- An Array, Object or CSV as a string describing the Baseline feature set support of all browser versions included in the module's data set via the getAllVersions() function.

You can use baseline-browser-mapping to help you determine minimum browser version support for your chosen Baseline feature set; or to analyse the level of support for different Baseline feature sets in your site's traffic by joining the data with your analytics data.

Install for local development

To install the package, run:

npm install --save-dev baseline-browser-mapping

baseline-browser-mapping depends on web-features and @mdn/browser-compat-data for core browser version selection, but the data is pre-packaged and minified. This package checks for updates to those modules and the supported downstream browsers on a daily basis and is updated frequently. Consider adding a script to your package.json to update baseline-browser-mapping and using it as part of your build process to ensure your data is as up to date as possible:

``javascript
"scripts": [
"refresh-baseline-browser-mapping": "npm i --save-dev baseline-browser-mapping@latest"
]
`

The minimum supported NodeJS version for baseline-browser-mapping is v8 in alignment with browserslist. For NodeJS versions earlier than v13.2, the require('baseline-browser-mapping') syntax should be used to import the module.

Keeping baseline-browser-mapping up to date

If you are only using this module to generate minimum browser versions for Baseline Widely available or Baseline year feature sets, you don't need to update this module frequently, as the backward looking data is reasonably stable.

However, if you are targeting Newly available, using the getAllVersions() function or heavily relying on the data for downstream browsers, you should update this module more frequently. If you target a feature cut off date within the last two months and your installed version of baseline-browser-mapping has data that is more than 2 months old, you will receive a console warning advising you to update to the latest version when you call getCompatibleVersions() or getAllVersions().

If you want to suppress these warnings you can use the suppressWarnings: true option in the configuration object passed to getCompatibleVersions() or getAllVersions(). Alternatively, you can use the BASELINE_BROWSER_MAPPING_IGNORE_OLD_DATA=true environment variable when running your build process. This module also respects the BROWSERSLIST_IGNORE_OLD_DATA=true environment variable. Environment variables can also be provided in a .env file from Node 20 onwards; however, this module does not load .env files automatically to avoid conflicts with other libraries with different requirements. You will need to use process.loadEnvFile() or a library like dotenv to load .env files before baseline-browser-mapping is called.

If you want to ensure reproducible builds, we strongly recommend using the widelyAvailableOnDate option to fix the Widely available date on a per build basis to ensure dependent tools provide the same output and you do not produce data staleness warnings. If you are using browserslist to target Baseline Widely available, consider automatically updating your browserslist configuration in package.json or .browserslistrc to baseline widely available on {YYYY-MM-DD} as part of your build process to ensure the same or sufficiently similar list of minimum browsers is reproduced for historical builds.

Importing baseline-browser-mapping

This module exposes two functions: getCompatibleVersions() and getAllVersions(), both which can be imported directly from baseline-browser-mapping:

`javascript
import {
getCompatibleVersions,
getAllVersions,
} from "baseline-browser-mapping";
`

If you want to load the script and data directly in a web page without hosting it yourself, consider using a CDN:

`html

`

Get Baseline Widely available browser versions or Baseline year browser versions

To get the current list of minimum browser versions compatible with Baseline Widely available features from the core browser set, call the getCompatibleVersions() function:

`javascript
getCompatibleVersions();
`

Executed on 7th March 2025, the above code returns the following browser versions:

`javascript
[
{ browser: "chrome", version: "105", release_date: "2022-09-02" },
{
browser: "chrome_android",
version: "105",
release_date: "2022-09-02",
},
{ browser: "edge", version: "105", release_date: "2022-09-02" },
{ browser: "firefox", version: "104", release_date: "2022-08-23" },
{
browser: "firefox_android",
version: "104",
release_date: "2022-08-23",
},
{ browser: "safari", version: "15.6", release_date: "2022-09-02" },
{
browser: "safari_ios",
version: "15.6",
release_date: "2022-09-02",
},
];
`

> [!NOTE]
> The minimum versions of each browser are not necessarily the final release before the Widely available cutoff date of TODAY - 30 MONTHS. Some earlier versions will have supported the full Widely available feature set.

$3

getCompatibleVersions() accepts an Object as an argument with configuration options. The defaults are as follows:

`javascript
{
targetYear: undefined,
widelyAvailableOnDate: undefined,
includeDownstreamBrowsers: false,
listAllCompatibleVersions: false,
suppressWarnings: false
}
`

#### targetYear

The targetYear option returns the minimum browser versions compatible with all Baseline Newly available features at the end of the specified calendar year. For example, calling:

`javascript
getCompatibleVersions({
targetYear: 2020,
});
`

Returns the following versions:

`javascript
[
{ browser: "chrome", version: "87", release_date: "2020-11-19" },
{
browser: "chrome_android",
version: "87",
release_date: "2020-11-19",
},
{ browser: "edge", version: "87", release_date: "2020-11-19" },
{ browser: "firefox", version: "83", release_date: "2020-11-17" },
{
browser: "firefox_android",
version: "83",
release_date: "2020-11-17",
},
{ browser: "safari", version: "14", release_date: "2020-09-16" },
{ browser: "safari_ios", version: "14", release_date: "2020-09-16" },
];
`

> [!NOTE]
> The minimum version of each browser is not necessarily the final version released in that calendar year. In the above example, Firefox 84 was the final version released in 2020; however Firefox 83 supported all of the features that were interoperable at the end of 2020.
> [!WARNING]
> You cannot use targetYear and widelyAavailableDate together. Please only use one of these options at a time.

#### widelyAvailableOnDate

The widelyAvailableOnDate option returns the minimum versions compatible with Baseline Widely available on a specified date in the format YYYY-MM-DD:

`javascript
getCompatibleVersions({
widelyAvailableOnDate: 2023-04-05,
});
`

> [!TIP]
> This option is useful if you provide a versioned library that targets Baseline Widely available on each version's release date and you need to provide a statement on minimum supported browser versions in your documentation.

#### includeDownstreamBrowsers

Setting includeDownstreamBrowsers to true will include browsers outside of the Baseline core browser set where it is possible to map those browsers to an upstream Chromium or Gecko version:

`javascript
getCompatibleVersions({
includeDownstreamBrowsers: true,
});
`

For more information on downstream browsers, see the section on downstream browsers below.

#### includeKaiOS

KaiOS is an operating system and app framework based on the Gecko engine from Firefox. KaiOS is based on the Gecko engine and feature support can be derived from the upstream Gecko version that each KaiOS version implements. However KaiOS requires other considerations beyond feature compatibility to ensure a good user experience as it runs on device types that do not have either mouse and keyboard or touch screen input in the way that all the other browsers supported by this module do.

`javascript
getCompatibleVersions({
includeDownstreamBrowsers: true,
includeKaiOS: true,
});
`

> [!NOTE]
> Including KaiOS requires you to include all downstream browsers using the includeDownstreamBrowsers option.

#### listAllCompatibleVersions

Setting listAllCompatibleVersions to true will include the minimum versions of each compatible browser, and all the subsequent versions:

`javascript
getCompatibleVersions({
listAllCompatibleVersions: true,
});
`

#### suppressWarnings

Setting suppressWarnings to true will suppress the console warning about old data:

`javascript
getCompatibleVersions({
suppressWarnings: true,
});
`

Get data for all browser versions

You may want to obtain data on all the browser versions available in this module for use in an analytics solution or dashboard. To get details of each browser version's level of Baseline support, call the getAllVersions() function:

`javascript
import { getAllVersions } from "baseline-browser-mapping";

getAllVersions();
`

By default, this function returns an Array of Objects and excludes downstream browsers:

`javascript
[
...
{
browser: "firefox_android", // Browser name
version: "125", // Browser version
release_date: "2024-04-16", // Release date
year: 2023, // Baseline year feature set the version supports
wa_compatible: true // Whether the browser version supports Widely available
},
...
]
`

For browser versions in @mdn/browser-compat-data that were released before Baseline can be defined, i.e. Baseline 2015, the year property is always the string: "pre_baseline".

$3

You may want to understand which recent browser versions support all Newly available features. You can replace the wa_compatible property with a supports property using the useSupport option:

`javascript
getAllVersions({
useSupports: true,
});
`

The supports property is optional and has two possible values:

- widely for browser versions that support all Widely available features.
- newly for browser versions that support all Newly available features.

Browser versions that do not support Widely or Newly available will not include the support property in the array or object outputs, and in the CSV output, the support column will contain an empty string. Browser versions that support all Newly available features also support all Widely available features.

$3

getAllVersions() accepts an Object as an argument with configuration options. The defaults are as follows:

`javascript
{
includeDownstreamBrowsers: false,
outputFormat: "array",
suppressWarnings: false
}
`

#### includeDownstreamBrowsers (in getAllVersions() output)

As with getCompatibleVersions(), you can set includeDownstreamBrowsers to true to include the Chromium and Gecko downstream browsers listed below.

`javascript
getAllVersions({
includeDownstreamBrowsers: true,
});
`

Downstream browsers include the same properties as core browsers, as well as the enginethey use and engine_version, for example:

`javascript
[
...
{
browser: "samsunginternet_android",
version: "27.0",
release_date: "2024-11-06",
engine: "Blink",
engine_version: "125",
year: 2023,
supports: "widely"
},
...
]
`

#### includeKaiOS (in getAllVersions() output)

As with getCompatibleVersions() you can include KaiOS in your output. The same requirement to have includeDownstreamBrowsers: true applies.

`javascript
getAllVersions({
includeDownstreamBrowsers: true,
includeKaiOS: true,
});
`

#### suppressWarnings (in getAllVersions() output)

As with getCompatibleVersions(), you can set suppressWarnings to true to suppress the console warning about old data:

`javascript
getAllVersions({
suppressWarnings: true,
});
`

#### outputFormat

By default, this function returns an Array of Objects which can be manipulated in Javascript or output to JSON.

To return an Object that nests keys , set outputFormat to object:

`javascript
getAllVersions({
outputFormat: "object",
});
`

In thise case, getAllVersions() returns a nested object with the browser IDs listed below as keys, and versions as keys within them:

`javascript
{
"chrome": {
"53": {
"year": 2016,
"release_date": "2016-09-07"
},
...
}
`

Downstream browsers will include extra fields for engine and engine_versions

`javascript
{
...
"webview_android": {
"53": {
"year": 2016,
"release_date": "2016-09-07",
"engine": "Blink",
"engine_version": "53"
},
...
}
`

To return a String in CSV format, set outputFormat to csv:

`javascript
getAllVersions({
outputFormat: "csv",
});
`

getAllVersions returns a String with a header row and comma-separated values for each browser version that you can write to a file or pass to another service. Core browsers will have "NULL" as the value for their engine and engine_version:

`csv
"browser","version","year","supports","release_date","engine","engine_version"
...
"chrome","24","pre_baseline","","2013-01-10","NULL","NULL"
...
"chrome","53","2016","","2016-09-07","NULL","NULL"
...
"firefox","135","2024","widely","2025-02-04","NULL","NULL"
"firefox","136","2024","newly","2025-03-04","NULL","NULL"
...
"ya_android","20.12","2020","year_only","2020-12-20","Blink","87"
...
`

> [!NOTE]
> The above example uses "includeDownstreamBrowsers": true

$3

The outputs of getAllVersions() are available as JSON or CSV files generated on a daily basis and hosted on GitHub pages:

- Core browsers only
- Array
- Object
- CSV
- Core browsers only, with supports property
- Array
- Object
- CSV
- Including downstream browsers
- Array
- Object
- CSV
- Including downstream browsers with supports property
- Array
- Object
- CSV

These files are updated on a daily basis.

CLI

baseline-browser-mapping includes a command line interface that exposes the same data and options as the getCompatibleVersions() function. To learn more about using the CLI, run:

`sh
npx baseline-browser-mapping --help
`

Downstream browsers

$3

The browser versions in this module come from two different sources:

- MDN's browser-compat-data module.
- Parsed user agent strings provided by useragents.io

MDN browser-compat-data is an authoritative source of information for the browsers it contains. The release dates for the Baseline core browser set and the mapping of downstream browsers to Chromium versions should be considered accurate.

Browser mappings from useragents.io are provided on a best effort basis. They assume that browser vendors are accurately stating the Chromium version they have implemented. The initial set of version mappings was derived from a bulk export in November 2024. This version was iterated over with a Regex match looking for a major Chrome version and a corresponding version of the browser in question, e.g.:

Mozilla/5.0 (Linux; U; Android 10; en-US; STK-L21 Build/HUAWEISTK-L21) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/100.0.4896.58 UCBrowser/13.8.2.1324 Mobile Safari/537.36

Shows UC Browser Mobile 13.8 implementing Chromium 100, and:

Mozilla/5.0 (Linux; arm_64; Android 11; Redmi Note 8 Pro) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.6613.123 YaBrowser/24.10.2.123.00 SA/3 Mobile Safari/537.36

Shows Yandex Browser Mobile 24.10 implementing Chromium 128. The Chromium version from this string is mapped to the corresponding Chrome version from MDN browser-compat-data.

> [!NOTE]
> Where possible, approximate release dates have been included based on useragents.io "first seen" data. useragents.io does not have "first seen" dates prior to June 2020. However, these browsers' Baseline compatibility is determined by their Chromium or Gecko version, so their release dates are more informative than critical.

This data is updated on a daily basis using a script triggered by a GitHub action. Useragents.io provides a private API for this module which exposes the last 7 days of newly seen user agents for the currently tracked browsers. If a new major version of one of the tracked browsers is encountered with a Chromium version that meets or exceeds the previous latest version of that browser, it is added to the src/data/downstream-browsers.json file with the date it was first seen by useragents.io as its release date.

KaiOS is an exception - its upstream version mappings are handled separately from the other browsers because they happen very infrequently.

$3

| Browser | ID | Core | Source |
| --------------------- | ------------------------- | ------- | ------------------------- |
| Chrome | chrome | true | MDN browser-compat-data |
| Chrome for Android | chrome_android | true | MDN browser-compat-data |
| Edge | edge | true | MDN browser-compat-data |
| Firefox | firefox | true | MDN browser-compat-data |
| Firefox for Android | firefox_android | true | MDN browser-compat-data |
| Safari | safari | true | MDN browser-compat-data |
| Safari on iOS | safari_ios | true | MDN browser-compat-data |
| Opera | opera | false | MDN browser-compat-data |
| Opera Android | opera_android | false | MDN browser-compat-data |
| Samsung Internet | samsunginternet_android | false | MDN browser-compat-data |
| WebView Android | webview_android | false | MDN browser-compat-data |
| QQ Browser Mobile | qq_android | false | useragents.io |
| UC Browser Mobile | uc_android | false | useragents.io |
| Yandex Browser Mobile | ya_android | false | useragents.io |
| KaiOS | kai_os | false | Manual |
| Facebook for Android | facebook_android | false | useragents.io |
| Instagram for Android | instagram_android | false` | useragents.io |

> [!NOTE]
> All the non-core browsers currently included implement Chromium or Gecko. Their inclusion in any of the above methods is based on the Baseline feature set supported by the Chromium or Gecko version they implement, not their release date.