# bcp-47-match
[![Build][build-badge]][build]
[![Coverage][coverage-badge]][coverage]
[![Downloads][downloads-badge]][downloads]
[![Size][size-badge]][size]
Match [BCP 47][spec] language tags with “language ranges” per [RFC 4647][match],
as done by the `:lang()` pseudo-class in CSS, or the `Accept-Language` HTTP
header.
Related to [`bcp-47`][bcp47].
## Contents
* [Install](#install)
* [Use](#use)
* [API](#api)
* [`match.basicFilter(tags[, ranges])`](#matchbasicfiltertags-ranges)
* [`match.extendedFilter(tags[, ranges])`](#matchextendedfiltertags-ranges)
* [`match.lookup(tags, ranges)`](#matchlookuptags-ranges)
* [Related](#related)
* [License](#license)
## Install
[npm][]:
```sh
npm install bcp-47-match
```
## Use
```js
var match = require('bcp-47-match')
var basic = match.basicFilter
var extended = match.extendedFilter
var lookup = match.lookup
var tags = ['en-GB', 'de-CH', 'en', 'de']
console.log(basic(tags, '*')) // => [ 'en-GB', 'de-CH', 'en', 'de' ]
console.log(basic(tags, 'en')) // => [ 'en-GB', 'en' ]
console.log(basic(tags, 'en-GB')) // => [ 'en-GB' ]
console.log(basic(tags, ['en-GB', 'en'])) // => [ 'en-GB', 'en' ]
console.log(basic(tags, 'jp')) // => []
console.log(extended(tags, '*')) // => [ 'en-GB', 'de-CH', 'en', 'de' ]
console.log(extended(tags, 'en')) // => [ 'en-GB', 'en' ]
console.log(extended(tags, 'en-GB')) // => [ 'en-GB' ]
console.log(extended(tags, '*-GB')) // => [ 'en-GB' ]
console.log(extended(tags, ['en-GB', 'en'])) // => [ 'en-GB', 'en' ]
console.log(extended(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
### `match.basicFilter(tags[, ranges])`
> [See Basic Filtering spec](https://tools.ietf.org/html/rfc4647#section-3.3.1)
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 | ✔︎ | ✔︎ | | | | |
| de-CH | ✔︎ | ✔︎ | ✔︎ | | | |
| de-CH-1996 | ✔︎ | ✔︎ | ✔︎ | | | |
| de-DE | ✔︎ | ✔︎ | | ✔︎ | | |
| de-DE-1996 | ✔︎ | ✔︎ | | ✔︎ | | |
| de-DE-x-goethe | ✔︎ | ✔︎ | | ✔︎ | | |
| de-Deva | ✔︎ | ✔︎ | | | | |
| de-Deva-DE | ✔︎ | ✔︎ | | | | |
| de-Latf-DE | ✔︎ | ✔︎ | | | | |
| de-Latn-DE | ✔︎ | ✔︎ | | | | |
| de-Latn-DE-1996 | ✔︎ | ✔︎ | | | | |
| de-x-DE | ✔︎ | ✔︎ | | | | |
| en | ✔︎ | | | | | |
| en-GB | ✔︎ | | | | | |
| zh | ✔︎ | | | | | |
| zh-Hans | ✔︎ | | | | | |
| zh-Hant | ✔︎ | | | | | |
View matching table
| Extended Filter | * | de | de-CH | de-DE | de-*-DE | *-CH |
| - | - | - | - | - | - | - |
| de | ✔︎ | ✔︎ | | | | |
| de-CH | ✔︎ | ✔︎ | ✔︎ | | | ✔︎ |
| de-CH-1996 | ✔︎ | ✔︎ | ✔︎ | | | ✔︎ |
| de-DE | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-DE-1996 | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-DE-x-goethe | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-Deva | ✔︎ | ✔︎ | | | | |
| de-Deva-DE | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-Latf-DE | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-Latn-DE | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-Latn-DE-1996 | ✔︎ | ✔︎ | | ✔︎ | ✔︎ | |
| de-x-DE | ✔︎ | ✔︎ | | | | |
| en | ✔︎ | | | | | |
| en-GB | ✔︎ | | | | | |
| zh | ✔︎ | | | | | |
| zh-Hans | ✔︎ | | | | | |
| zh-Hant | ✔︎ | | | | | |
View matching table
| Lookup | * | de | de-CH | de-DE | de-*-DE | *-CH |
| - | - | - | - | - | - | - |
| de | | ✔︎︎ | ✔︎︎ | ✔︎ | ✔︎ | ✔︎ |
| de-CH | | | ✔︎ | | | ✔︎ |
| de-CH-1996 | | | | | | ✔︎ |
| de-DE | | | | ✔︎ | | ✔︎ |
| de-DE-1996 | | | | | | ✔︎ |
| de-DE-x-goethe | | | | | | ✔︎ |
| de-Deva | | | | | | ✔︎ |
| de-Deva-DE | | | | | | ✔︎ |
| de-Latf-DE | | | | | | ✔︎ |
| de-Latn-DE | | | | | | ✔︎ |
| de-Latn-DE-1996 | | | | | | ✔︎ |
| de-x-DE | | | | | | ✔︎ |
| en | | | | | | ✔︎ |
| en-GB | | | | | | ✔︎ |
| zh | | | | | | ✔︎ |
| zh-Hans | | | | | | ✔︎ |
| zh-Hant | | | | | | ✔︎ |