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

## Overview

The `isSameLanguage` function checks if 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 first hyphen)
- Ignores regional, script, and variant differences
- Essential for language-based content organization
- Works with variable number of parameters

## Next steps

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