Locale parsing

IETF language tags are used to identify locales, specifying one or more of the following:

• ISO 639 code indicating the language
• ISO 15924 code indicating the script or writing system
• ISO 3166-1 or UN M.49 code indicating the territory or world region
• IANA variant subtag
• Extension subtags used for indicating the numbering system, calendar, collation, etc.
• BCP 47 Private use subtag which uses the 'x' extension, for an application's own purposes

This library supports parsing of language tags, and what we refer to as "resolution" which fills in any missing subtags with the most likely value.

Parsing

Parsing converts a locale identifier like "en-US" into an language tag object, according to the validation rules of IETF language tags.

The parser will also accept underscores, which appear in locale identifiers in some languages, as with Java's Locale object.

In the example below we use the CLDRFramework.parseLanguageTag function to parse several identifiers into LanguageTag objects, and calling several methods on them.

import { CLDRFramework } from '@phensley/cldr';

const { parseLanguageTag } = CLDRFramework;

const ids = [
  'en-US',
  'und-Latn-ZZ',
  'fr_CA',
  'no-GB-u-ca-gregory-u-nu-mathmono'
];

for (const id of ids) {
  const tag = parseLanguageTag(id);

  log(tag.language());
  log(tag.script());
  log(tag.region());
  log(tag.compact());
  log(tag.expanded());
  log(tag.extensions());
  log();
}

en
Zzzz
US
en-US
en-Zzzz-US
{}
 
und
Latn
ZZ
und-Latn
und-Latn-ZZ
{}
 
fr
Zzzz
CA
fr-CA
fr-Zzzz-CA
{}
 
no
Zzzz
GB
no-GB-u-ca-gregory-nu-mathmono
no-Zzzz-GB-u-ca-gregory-nu-mathmono
{ u: [ 'ca-gregory', 'nu-mathmono' ] }