# generaltranslation: General Translation Core SDK: isSupersetLocale
URL: https://generaltranslation.com/en-GB/docs/core/class/methods/locales/is-superset-locale.mdx
---
title: isSupersetLocale
description: API reference for the GT isSupersetLocale method
---

## Overview

The `isSupersetLocale` method checks whether one locale is a superset of another locale in the BCP-47 hierarchy.
A superset locale is more general and can serve as a fallback for more specific locales.

***

## Reference

### Parameters

<TypeTable
  type={{
  "superLocale": {
    type: 'string',
    optional: false,
  },
  "subLocale": {
    type: 'string',
    optional: false,
  }
}}
/>

### Returns

`boolean` - `true` if superLocale is a superset of subLocale

***

## Examples

```typescript
const gt = new GT();

// Base language is superset of regional variant
console.log(gt.isSupersetLocale('en', 'en-US')); // true
console.log(gt.isSupersetLocale('es', 'es-ES')); // true
console.log(gt.isSupersetLocale('zh', 'zh-CN')); // true

// Regional variant is NOT superset of base language
console.log(gt.isSupersetLocale('en-US', 'en')); // false
console.log(gt.isSupersetLocale('es-ES', 'es')); // false

// Same locales
console.log(gt.isSupersetLocale('en-US', 'en-US')); // true

// Different languages
console.log(gt.isSupersetLocale('en', 'es-ES')); // false
```

***


## Notes

* Uses BCP-47 locale hierarchy for comparison
* A locale is always a superset of itself
* Base languages are supersets of their regional variants
* Returns false for completely different languages

## Next steps

* Compare languages with [`isSameLanguage`](/docs/core/class/methods/locales/is-same-language)
* Compare dialects with [`isSameDialect`](/docs/core/class/methods/locales/is-same-dialect)