# generaltranslation: General Translation Core SDK: isSameLanguage
URL: https://generaltranslation.com/en-GB/docs/core/functions/locales/is-same-language.mdx
---
title: isSameLanguage
description: API reference for the isSameLanguage function
---

## Overview

The `isSameLanguage` function checks whether multiple BCP-47 locale codes represent the same base language, ignoring regional differences.

***

## Reference

### Parameters

<TypeTable
  type={{
  "...locales": {
    type: '(string | string[])[]',
    optional: false,
  }
}}
/>

### Returns

`boolean` - `true` if all locale codes represent the same base language

***

## Examples

```typescript
import { isSameLanguage } from 'generaltranslation';

// Same language, different regions
console.log(isSameLanguage('en-US', 'en-GB')); // true
console.log(isSameLanguage('es-ES', 'es-MX')); // true
console.log(isSameLanguage('zh-CN', 'zh-TW')); // true

// Different languages
console.log(isSameLanguage('en-US', 'es-ES')); // false
console.log(isSameLanguage('fr-FR', 'de-DE')); // false
```

***


## Notes

* Compares only base language codes (before the first hyphen)
* Ignores regional, script, and variant differences
* Essential for language-based content organisation
* Works with a variable number of parameters

## Next steps

* Use the GT class method [`isSameLanguage`](/docs/core/class/methods/locales/is-same-language)
* Compare dialects using [`isSameDialect`](/docs/core/functions/locales/is-same-dialect)