316 lines
9.2 KiB
Markdown
316 lines
9.2 KiB
Markdown
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# bcp-47-match
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[![Build][build-badge]][build]
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[![Coverage][coverage-badge]][coverage]
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[![Downloads][downloads-badge]][downloads]
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[![Size][size-badge]][size]
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Match BCP 47 language tags with language ranges per RFC 4647.
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## Contents
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* [What is this?](#what-is-this)
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* [When should I use this?](#when-should-i-use-this)
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* [Install](#install)
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* [Use](#use)
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* [API](#api)
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* [`basicFilter(tags[, ranges='*'])`](#basicfiltertags-ranges)
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* [`extendedFilter(tags[, ranges='*'])`](#extendedfiltertags-ranges)
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* [`lookup(tags, ranges)`](#lookuptags-ranges)
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* [Types](#types)
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* [Compatibility](#compatibility)
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* [Security](#security)
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* [Related](#related)
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* [Contribute](#contribute)
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* [License](#license)
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## What is this?
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This package can match [BCP 47][spec] language tags with “language ranges” per
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[RFC 4647][match].
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This is done by the `:lang()` pseudo class in CSS, the `Accept-Language` HTTP
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header, and a few other places.
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## When should I use this?
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You can use this package if you want to choose a certain document based on
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language tags.
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## Install
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This package is [ESM only][esm].
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In Node.js (version 14.14+, 16.0+), install with [npm][]:
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```sh
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npm install bcp-47-match
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```
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In Deno with [`esm.sh`][esmsh]:
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```js
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import * as bcp47Match from 'https://esm.sh/bcp-47-match@2'
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```
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In browsers with [`esm.sh`][esmsh]:
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```html
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<script type="module">
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import * as bcp47Match from 'https://esm.sh/bcp-47-match@2?bundle'
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</script>
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```
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## Use
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```js
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import {basicFilter, extendedFilter, lookup} from 'bcp-47-match'
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const tags = ['en-GB', 'de-CH', 'en', 'de']
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console.log(basicFilter(tags, '*')) // => [ 'en-GB', 'de-CH', 'en', 'de' ]
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console.log(basicFilter(tags, 'en')) // => [ 'en-GB', 'en' ]
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console.log(basicFilter(tags, 'en-GB')) // => [ 'en-GB' ]
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console.log(basicFilter(tags, ['en-GB', 'en'])) // => [ 'en-GB', 'en' ]
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console.log(basicFilter(tags, 'jp')) // => []
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console.log(extendedFilter(tags, '*')) // => [ 'en-GB', 'de-CH', 'en', 'de' ]
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console.log(extendedFilter(tags, 'en')) // => [ 'en-GB', 'en' ]
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console.log(extendedFilter(tags, 'en-GB')) // => [ 'en-GB' ]
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console.log(extendedFilter(tags, '*-GB')) // => [ 'en-GB' ]
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console.log(extendedFilter(tags, ['en-GB', 'en'])) // => [ 'en-GB', 'en' ]
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console.log(extendedFilter(tags, 'jp')) // => []
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console.log(lookup(tags, 'en')) // => 'en'
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console.log(lookup(tags, 'en-GB')) // => 'en-GB'
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console.log(lookup(tags, ['en-GB', 'en'])) // => 'en-GB'
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console.log(lookup(tags, ['en', 'en-GB'])) // => 'en'
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console.log(lookup(tags, 'jp')) // => undefined
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```
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## API
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This package exports the identifier `basicFilter`, `extendedFilter`, and
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`lookup`.
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There is no default export.
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### `basicFilter(tags[, ranges='*'])`
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> 👉 **Note**: See
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> [Basic Filtering spec](https://tools.ietf.org/html/rfc4647#section-3.3.1)
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Match language tags to a list of simple ranges.
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Searches for matches between the first range and all tags, and continues
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with further ranges.
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Returns a list of matching tags in the order they matched.
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<details><summary>View matching table</summary>
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| Basic Filter | `*` | `de` | `de-CH` | `de-DE` | `de-*-DE` | `*-CH` |
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| - | - | - | - | - | - | - |
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| `de` | ✔︎ | ✔︎ | | | | |
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| `de-CH` | ✔︎ | ✔︎ | ✔︎ | | | |
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| `de-CH-1996` | ✔︎ | ✔︎ | ✔︎ | | | |
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| `de-DE` | ✔︎ | ✔︎ | | ✔︎ | | |
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| `de-DE-1996` | ✔︎ | ✔︎ | | ✔︎ | | |
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| `de-DE-x-goethe` | ✔︎ | ✔︎ | | ✔︎ | | |
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| `de-Deva` | ✔︎ | ✔︎ | | | | |
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| `de-Deva-DE` | ✔︎ | ✔︎ | | | | |
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| `de-Latf-DE` | ✔︎ | ✔︎ | | | | |
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| `de-Latn-DE` | ✔︎ | ✔︎ | | | | |
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| `de-Latn-DE-1996` | ✔︎ | ✔︎ | | | | |
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| `de-x-DE` | ✔︎ | ✔︎ | | | | |
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| `en` | ✔︎ | | | | | |
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| `en-GB` | ✔︎ | | | | | |
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| `zh` | ✔︎ | | | | | |
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| `zh-Hans` | ✔︎ | | | | | |
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| `zh-Hant` | ✔︎ | | | | | |
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</details>
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###### Parameters
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* `tags` (`string` or `Array<string>`)
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— list of BCP 47 tags
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* `ranges` (`string` or `Array<string>`, default: `'*'`)
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— list of RFC 4647
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[basic ranges][basic-range]
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(aka, matching `/^(\*|[a-z]{1,8}(-[a-z0-9]{1,8})*)$/i`)
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###### Returns
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Possibly empty list of matching tags in the order they matched
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(`Array<string>`).
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### `extendedFilter(tags[, ranges='*'])`
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> 👉 **Note**: See
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> [Extended Filtering spec](https://tools.ietf.org/html/rfc4647#section-3.3.2)
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Match language tags to a list of extended ranges.
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Searches for matches between the first range and all tags, and continues
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with further ranges.
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<details><summary>View matching table</summary>
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| Extended Filter | `*` | `de` | `de-CH` | `de-DE` | `de-*-DE` | `*-CH` |
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| - | - | - | - | - | - | - |
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| `de` | ✔︎ | ✔︎ | | | | |
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| `de-CH` | ✔︎ | ✔︎ | ✔︎ | | | ✔︎ |
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| `de-CH-1996` | ✔︎ | ✔︎ | ✔︎ | | | ✔︎ |
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| `de-DE` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-DE-1996` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-DE-x-goethe` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-Deva` | ✔︎ | ✔︎ | | | | |
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| `de-Deva-DE` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-Latf-DE` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-Latn-DE` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-Latn-DE-1996` | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
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| `de-x-DE` | ✔︎ | ✔︎ | | | | |
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| `en` | ✔︎ | | | | | |
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| `en-GB` | ✔︎ | | | | | |
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| `zh` | ✔︎ | | | | | |
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| `zh-Hans` | ✔︎ | | | | | |
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| `zh-Hant` | ✔︎ | | | | | |
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</details>
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###### Parameters
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* `tags` (`string` or `Array<string>`)
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— list of BCP 47 tags
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* `ranges` (`string` or `Array<string>`, default: `'*'`)
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— list of RFC 4647 [extended ranges][extended-range]
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(aka, matching `/^(\*|[a-z]{1,8})(-(\*|[a-z0-9]{1,8}))*$/i`)
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###### Returns
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Possibly empty list of matching tags in the order they matched
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(`Array<string>`).
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### `lookup(tags, ranges)`
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> 👉 **Note**: See
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> [Lookup spec](https://tools.ietf.org/html/rfc4647#section-3.4)
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Find the best language tag that matches a list of ranges.
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Searches for a match between the first range and all tags, and continues
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with further ranges.
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Returns the first match, if any.
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<details><summary>View matching table</summary>
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| Lookup | `*` | `de` | `de-CH` | `de-DE` | `de-*-DE` | `*-CH` |
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| - | - | - | - | - | - | - |
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| `de` | | ✔︎︎ | ✔︎︎ | ✔︎ | ✔︎ | ✔︎ |
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| `de-CH` | | | ✔︎ | | | ✔︎ |
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| `de-CH-1996` | | | | | | ✔︎ |
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| `de-DE` | | | | ✔︎ | | ✔︎ |
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| `de-DE-1996` | | | | | | ✔︎ |
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| `de-DE-x-goethe` | | | | | | ✔︎ |
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| `de-Deva` | | | | | | ✔︎ |
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| `de-Deva-DE` | | | | | | ✔︎ |
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| `de-Latf-DE` | | | | | | ✔︎ |
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| `de-Latn-DE` | | | | | | ✔︎ |
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| `de-Latn-DE-1996` | | | | | | ✔︎ |
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| `de-x-DE` | | | | | | ✔︎ |
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| `en` | | | | | | ✔︎ |
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| `en-GB` | | | | | | ✔︎ |
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| `zh` | | | | | | ✔︎ |
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| `zh-Hans` | | | | | | ✔︎ |
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| `zh-Hant` | | | | | | ✔︎ |
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</details>
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###### Parameters
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* `tags` (`string` or `Array<string>`)
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— list of BCP 47 tags
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* `ranges` (`string` or `Array<string>`)
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— list of RFC 4647 basic ranges (but `*` is ignored)
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###### Returns
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First matching tag in `tags`, `undefined` otherwise (`string?`).
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## Types
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This package is fully typed with [TypeScript][].
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It exports no additional types.
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## Compatibility
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This package is at least compatible with all maintained versions of Node.js.
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As of now, that is Node.js 14.14+ and 16.0+.
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It also works in Deno and modern browsers.
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## Security
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This package is safe.
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## Related
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* [`wooorm/bcp-47`](https://github.com/wooorm/bcp-47)
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— parse and serialize BCP 47 language tags
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* [`wooorm/bcp-47-normalize`](https://github.com/wooorm/bcp-47-normalize)
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— normalize, canonicalize, and format BCP 47 tags
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* [`wooorm/iso-3166`](https://github.com/wooorm/iso-3166)
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— ISO 3166 codes
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* [`wooorm/iso-639-2`](https://github.com/wooorm/iso-639-2)
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— ISO 639-2 codes
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* [`wooorm/iso-639-3`](https://github.com/wooorm/iso-639-3)
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— ISO 639-3 codes
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* [`wooorm/iso-15924`](https://github.com/wooorm/iso-15924)
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— ISO 15924 codes
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* [`wooorm/un-m49`](https://github.com/wooorm/un-m49)
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— UN M49 codes
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## Contribute
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Yes please!
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See [How to Contribute to Open Source][contribute].
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## License
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[MIT][license] © [Titus Wormer][author]
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<!-- Definitions -->
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[build-badge]: https://github.com/wooorm/bcp-47-match/workflows/main/badge.svg
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[build]: https://github.com/wooorm/bcp-47-match/actions
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[coverage-badge]: https://img.shields.io/codecov/c/github/wooorm/bcp-47-match.svg
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[coverage]: https://codecov.io/github/wooorm/bcp-47-match
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[downloads-badge]: https://img.shields.io/npm/dm/bcp-47-match.svg
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[downloads]: https://www.npmjs.com/package/bcp-47-match
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[size-badge]: https://img.shields.io/bundlephobia/minzip/bcp-47-match.svg
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[size]: https://bundlephobia.com/result?p=bcp-47-match
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[npm]: https://docs.npmjs.com/cli/install
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[esmsh]: https://esm.sh
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[license]: license
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[author]: https://wooorm.com
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[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
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[typescript]: https://www.typescriptlang.org
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[contribute]: https://opensource.guide/how-to-contribute/
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[spec]: https://tools.ietf.org/html/bcp47
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[match]: https://tools.ietf.org/html/rfc4647
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[basic-range]: https://tools.ietf.org/html/rfc4647#section-2.1
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[extended-range]: https://tools.ietf.org/html/rfc4647#section-2.2
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