bcp-47

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Parse and stringify [BCP 47][spec] language tags.

Contents

* What is this?
* When should I use this?
* Install
* Use
* API
* [parse(tag[, options])](#parsetag-options)
* stringify(schema)
* Schema
* function warning(reason, code, offset)
* Types
* Compatibility
* Security
* Related
* Contribute
* License

What is this?

This is a package that can parse BCP 47 language tags to an object representing
them, and serialize those objects back into language tags.
It supports a forgiving mode to handle incorrect BCP 47 tags and can emit
warnings about problems in incorrect tags.

When should I use this?

You can use this package if you need to access the data stored in BCP 47
language tags.
You can also use this package if you want to check (lint) or manipulate tags.

Install

This package is [ESM only][esm].
In Node.js (version 12.20+, 14.14+, or 16.0+), install with [npm][]:

``sh
npm install bcp-47
`

In Deno with [Skypack][]:

`js
import * as bcp47 from 'https://cdn.skypack.dev/bcp-47@2?dts'
`

In browsers with [Skypack][]:

`html

`

Use

`js
import {parse, stringify} from 'bcp-47'

const schema = parse('hy-Latn-IT-arevela')

console.log(schema)
console.log(stringify(schema))
`

Yields:

`js
{ language: 'hy',
extendedLanguageSubtags: [],
script: 'Latn',
region: 'IT',
variants: ['arevela'],
extensions: [],
privateuse: [],
irregular: null,
regular: null }
'hy-Latn-IT-arevela'
`

API

This package exports the following identifiers: parse and stringify.
There is no default export.

$3

Parse a BCP 47 tag into a language schema.
Note that the algorithm is case insensitive.

###### options.normalize

Whether to normalize legacy tags when possible (boolean, default:
true).
For example, i-klingon does not match the BCP 47 language algorithm but is
considered valid by BCP 47 nonetheless.
It is suggested to use tlh instead (the ISO 639-3 code for Klingon).
When normalize is true, passing i-klingon or other deprecated tags, is
handled as if their suggested valid tag was given instead.

###### options.forgiving

By default, when an error is encountered, an empty object is returned.
When in forgiving mode, all found values up to the point of the error
are included (boolean, default: false).
So, for example, where by default en-GB-abcdefghi an empty object is returned
(as the language variant is too long), in forgiving mode the language of
schema is populated with en and the region is populated with GB.

###### options.warning

When given, warning is called when an error is encountered
([Function][warning]).

###### Returns

Parsed BCP 47 language tag ([Schema][schema]).

###### Throws

When tag is null or undefined.

$3

Compile a [schema][schema] to a BCP 47 language tag.

###### Returns

BCP 47 language tag (string).

$3

A schema represents a language tag.
A schema is deemed empty when it has neither language, irregular, regular,
nor privateuse (where an empty privateuse array is handled as no
privateuse as well).

###### schema.language

Two or three character [ISO 639][iso-639] language code, four character reserved
language code, or 5 to 8 (inclusive) characters registered language subtag
(string).
For example, en (English) or cmn (Mandarin Chinese).

###### schema.extendedLanguageSubtags

Selected three-character [ISO 639][iso-639] codes(Array), such as
yue in zh-yue-HK (Chinese, Cantonese, as used in Hong Kong SAR).

###### schema.script

Four character [ISO 15924][iso-15924] script code (string), such as Latn in
hy-Latn-IT-arevela (Eastern Armenian written in Latin script, as used in
Italy).

###### schema.region

Two alphabetical character [ISO 3166-1][iso-3166-1] code or three digit
[UN M49][un-m49] code (string).
For example, CN in cmn-Hans-CN (Mandarin Chinese, Simplified script, as used
in China) or 419 in es-419 (Spanish as used in Latin America and the
Caribbean).

###### schema.variants

5 to 8 (inclusive) character language variants (Array), such as
rozaj and biske in sl-rozaj-biske (San Giorgio dialect of Resian dialect
of Slovenian).

###### schema.extensions

List of extensions (Array