bcp-47-match

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Match BCP 47 language tags with language ranges per RFC 4647.

Contents

* 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

What is this?

This package can match [BCP 47][spec] language tags with “language ranges” per
[RFC 4647][match].
This is done by the :lang() pseudo class in CSS, the Accept-Language HTTP
header, and a few other places.

When should I use this?

You can use this package if you want to choose a certain document based on
language tags.

Install

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

`

Use

`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
`

API

This package exports the identifier basicFilter, extendedFilter, and
lookup.
There is no default export.

$3

> 👉 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.

###### Parameters

* tags (string or Array)
— list of BCP 47 tags
ranges (string or Array, default: '')
— list of RFC 4647
[basic ranges][basic-range]
(aka, matching /^(\|[a-z]{1,8}(-[a-z0-9]{1,8}))$/i)

###### Returns

Possibly empty list of matching tags in the order they matched
(Array).

$3

> 👉 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.

###### Parameters

* tags (string or Array)
— list of BCP 47 tags
ranges (string or Array, default: '')
— list of RFC 4647 [extended ranges][extended-range]
(aka, matching /^(\|[a-z]{1,8})(-(\|[a-z0-9]{1,8}))*$/i)

###### Returns

Possibly empty list of matching tags in the order they matched
(Array).

$3

> 👉 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.

###### Parameters

* tags (string or Array)
— list of BCP 47 tags
* ranges (string or Array)
— list of RFC 4647 basic ranges (but * is ignored)

###### Returns

First matching tag in tags, undefined otherwise (string?).

Types

This package is fully typed with [TypeScript][].
It exports no additional types.

Compatibility

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.

Security

This package is safe.

Related

* wooorm/bcp-47
— parse and serialize BCP 47 language tags
* wooorm/bcp-47-normalize
— normalize, canonicalize, and format BCP 47 tags
* wooorm/iso-3166
— ISO 3166 codes
* wooorm/iso-639-2
— ISO 639-2 codes
* wooorm/iso-639-3
— ISO 639-3 codes
* wooorm/iso-15924
— ISO 15924 codes
* wooorm/un-m49`
— UN M49 codes

Contribute

Yes please!
See [How to Contribute to Open Source][contribute].

License

[MIT][license] © [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