Overview

The standardizeLocale method standardises a BCP-47 locale code to ensure correct formatting and casing. It converts locale codes to their canonical form, making them suitable for use with internationalisation APIs and ensuring consistency across your application.

Reference

Parameters

Parameter description

Returns

string - The standardised BCP-47 locale code, or empty string if the input is invalid

Throws

• Error – if no locale is provided and the instance has no targetLocale configured

Behaviour

Common formatting corrections applied:

• en_US → en-US (underscore to hyphen)
• zh_cn → zh-CN (underscore to hyphen, casing)
• EN-gb → en-GB (language lowercase, region uppercase)
• Fr-ca → fr-CA (proper casing throughout)
• ja_jp → ja-JP (underscore and casing)

Examples

const gt = new GT({
  sourceLocale: 'en',
  targetLocale: 'es-ES'
});

// Standardise various locale formats
console.log(gt.standardizeLocale('en_us')); // "en-US"
console.log(gt.standardizeLocale('zh_cn')); // "zh-CN"
console.log(gt.standardizeLocale('EN-gb')); // "en-GB"
console.log(gt.standardizeLocale('fr-ca')); // "fr-CA"

// Already standardised locales pass through unchanged
console.log(gt.standardizeLocale('es-ES')); // "es-ES"
console.log(gt.standardizeLocale('ja-JP')); // "ja-JP"

Notes

• Converts underscores to hyphens and normalises casing
• Returns an empty string for invalid locale codes
• Language codes are lowercase; region codes are uppercase
• Preserves locale extensions and variants when present

Next steps

• Validate standardised locales with isValidLocale
• Resolve canonical locales with resolveCanonicalLocale
• Get locale properties with getLocaleProperties