Match BCP 47 language tags with language ranges per RFC 4647
npm install bcp-47-match[![Build][build-badge]][build]
[![Coverage][coverage-badge]][coverage]
[![Downloads][downloads-badge]][downloads]
[![Size][size-badge]][size]
Match BCP 47 language tags with language ranges per RFC 4647.
* What is this?
* When should I use this?
* Install
* Use
* API
[basicFilter(tags[, ranges=''])](#basicfiltertags-ranges)
[extendedFilter(tags[, ranges=''])](#extendedfiltertags-ranges)
* lookup(tags, ranges)
* Types
* Compatibility
* Security
* Related
* Contribute
* License
This package can match [BCP 47][spec] language tags with βlanguage rangesβ per
[RFC 4647][match].
This is done by the :lang() pseudo class in CSS, the Accept-Language HTTP
header, and a few other places.
You can use this package if you want to choose a certain document based on
language tags.
This package is [ESM only][esm].
In Node.js (version 14.14+, 16.0+), install with [npm][]:
``sh`
npm install bcp-47-match
In Deno with [esm.sh][esmsh]:
`js`
import * as bcp47Match from 'https://esm.sh/bcp-47-match@2'
In browsers with [esm.sh][esmsh]:
`html`
`js
import {basicFilter, extendedFilter, lookup} from 'bcp-47-match'
const tags = ['en-GB', 'de-CH', 'en', 'de']
console.log(basicFilter(tags, '*')) // => [ 'en-GB', 'de-CH', 'en', 'de' ]
console.log(basicFilter(tags, 'en')) // => [ 'en-GB', 'en' ]
console.log(basicFilter(tags, 'en-GB')) // => [ 'en-GB' ]
console.log(basicFilter(tags, ['en-GB', 'en'])) // => [ 'en-GB', 'en' ]
console.log(basicFilter(tags, 'jp')) // => []
console.log(extendedFilter(tags, '*')) // => [ 'en-GB', 'de-CH', 'en', 'de' ]
console.log(extendedFilter(tags, 'en')) // => [ 'en-GB', 'en' ]
console.log(extendedFilter(tags, 'en-GB')) // => [ 'en-GB' ]
console.log(extendedFilter(tags, '*-GB')) // => [ 'en-GB' ]
console.log(extendedFilter(tags, ['en-GB', 'en'])) // => [ 'en-GB', 'en' ]
console.log(extendedFilter(tags, 'jp')) // => []
console.log(lookup(tags, 'en')) // => 'en'
console.log(lookup(tags, 'en-GB')) // => 'en-GB'
console.log(lookup(tags, ['en-GB', 'en'])) // => 'en-GB'
console.log(lookup(tags, ['en', 'en-GB'])) // => 'en'
console.log(lookup(tags, 'jp')) // => undefined
`
This package exports the identifier basicFilter, extendedFilter, andlookup.
There is no default export.
> π Note: See
> Basic Filtering spec
Match language tags to a list of simple ranges.
Searches for matches between the first range and all tags, and continues
with further ranges.
Returns a list of matching tags in the order they matched.
View matching table
| Basic Filter | | de | de-CH | de-DE | de--DE | *-CH |de
| - | - | - | - | - | - | - |
| | βοΈ | βοΈ | | | | |de-CH
| | βοΈ | βοΈ | βοΈ | | | |de-CH-1996
| | βοΈ | βοΈ | βοΈ | | | |de-DE
| | βοΈ | βοΈ | | βοΈ | | |de-DE-1996
| | βοΈ | βοΈ | | βοΈ | | |de-DE-x-goethe
| | βοΈ | βοΈ | | βοΈ | | |de-Deva
| | βοΈ | βοΈ | | | | |de-Deva-DE
| | βοΈ | βοΈ | | | | |de-Latf-DE
| | βοΈ | βοΈ | | | | |de-Latn-DE
| | βοΈ | βοΈ | | | | |de-Latn-DE-1996
| | βοΈ | βοΈ | | | | |de-x-DE
| | βοΈ | βοΈ | | | | |en
| | βοΈ | | | | | |en-GB
| | βοΈ | | | | | |zh
| | βοΈ | | | | | |zh-Hans
| | βοΈ | | | | | |zh-Hant
| | βοΈ | | | | | |
###### Parameters
* tags (string or Array)ranges
β list of BCP 47 tags
(string or Array, default: '')/^(\|[a-z]{1,8}(-[a-z0-9]{1,8}))$/i
β list of RFC 4647
[basic ranges][basic-range]
(aka, matching )
###### Returns
Possibly empty list of matching tags in the order they matched
(Array).
> π Note: See
> Extended Filtering spec
Match language tags to a list of extended ranges.
Searches for matches between the first range and all tags, and continues
with further ranges.
View matching table
| Extended Filter | | de | de-CH | de-DE | de--DE | *-CH |de
| - | - | - | - | - | - | - |
| | βοΈ | βοΈ | | | | |de-CH
| | βοΈ | βοΈ | βοΈ | | | βοΈ |de-CH-1996
| | βοΈ | βοΈ | βοΈ | | | βοΈ |de-DE
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-DE-1996
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-DE-x-goethe
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-Deva
| | βοΈ | βοΈ | | | | |de-Deva-DE
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-Latf-DE
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-Latn-DE
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-Latn-DE-1996
| | βοΈ | βοΈ | | βοΈ | βοΈ | |de-x-DE
| | βοΈ | βοΈ | | | | |en
| | βοΈ | | | | | |en-GB
| | βοΈ | | | | | |zh
| | βοΈ | | | | | |zh-Hans
| | βοΈ | | | | | |zh-Hant
| | βοΈ | | | | | |
###### Parameters
* tags (string or Array)ranges
β list of BCP 47 tags
(string or Array, default: '')/^(\|[a-z]{1,8})(-(\|[a-z0-9]{1,8}))*$/i
β list of RFC 4647 [extended ranges][extended-range]
(aka, matching )
###### Returns
Possibly empty list of matching tags in the order they matched
(Array).
> π Note: See
> Lookup spec
Find the best language tag that matches a list of ranges.
Searches for a match between the first range and all tags, and continues
with further ranges.
Returns the first match, if any.
View matching table
| Lookup | | de | de-CH | de-DE | de--DE | *-CH |de
| - | - | - | - | - | - | - |
| | | βοΈοΈ | βοΈοΈ | βοΈ | βοΈ | βοΈ |de-CH
| | | | βοΈ | | | βοΈ |de-CH-1996
| | | | | | | βοΈ |de-DE
| | | | | βοΈ | | βοΈ |de-DE-1996
| | | | | | | βοΈ |de-DE-x-goethe
| | | | | | | βοΈ |de-Deva
| | | | | | | βοΈ |de-Deva-DE
| | | | | | | βοΈ |de-Latf-DE
| | | | | | | βοΈ |de-Latn-DE
| | | | | | | βοΈ |de-Latn-DE-1996
| | | | | | | βοΈ |de-x-DE
| | | | | | | βοΈ |en
| | | | | | | βοΈ |en-GB
| | | | | | | βοΈ |zh
| | | | | | | βοΈ |zh-Hans
| | | | | | | βοΈ |zh-Hant
| | | | | | | βοΈ |
###### Parameters
* tags (string or Array)ranges
β list of BCP 47 tags
* (string or Array)*
β list of RFC 4647 basic ranges (but is ignored)
###### Returns
First matching tag in tags, undefined otherwise (string?).
This package is fully typed with [TypeScript][].
It exports no additional types.
This package is at least compatible with all maintained versions of Node.js.
As of now, that is Node.js 14.14+ and 16.0+.
It also works in Deno and modern browsers.
This package is safe.
* wooorm/bcp-47
β parse and serialize BCP 47 language tags
* wooorm/bcp-47-normalize
β normalize, canonicalize, and format BCP 47 tags
* wooorm/iso-3166
β ISO 3166 codes
* wooorm/iso-639-2
β ISO 639-2 codes
* wooorm/iso-639-3
β ISO 639-3 codes
* wooorm/iso-15924
β ISO 15924 codes
* wooorm/un-m49`
β UN M49 codes
Yes please!
See [How to Contribute to Open Source][contribute].
[MIT][license] Β© [Titus Wormer][author]
[build-badge]: https://github.com/wooorm/bcp-47-match/workflows/main/badge.svg
[build]: https://github.com/wooorm/bcp-47-match/actions
[coverage-badge]: https://img.shields.io/codecov/c/github/wooorm/bcp-47-match.svg
[coverage]: https://codecov.io/github/wooorm/bcp-47-match
[downloads-badge]: https://img.shields.io/npm/dm/bcp-47-match.svg
[downloads]: https://www.npmjs.com/package/bcp-47-match
[size-badge]: https://img.shields.io/bundlephobia/minzip/bcp-47-match.svg
[size]: https://bundlephobia.com/result?p=bcp-47-match
[npm]: https://docs.npmjs.com/cli/install
[esmsh]: https://esm.sh
[license]: license
[author]: https://wooorm.com
[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
[typescript]: https://www.typescriptlang.org
[contribute]: https://opensource.guide/how-to-contribute/
[spec]: https://tools.ietf.org/html/bcp47
[match]: https://tools.ietf.org/html/rfc4647
[basic-range]: https://tools.ietf.org/html/rfc4647#section-2.1
[extended-range]: https://tools.ietf.org/html/rfc4647#section-2.2