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

## Overview

The `isSameLanguage` method checks if multiple BCP-47 locale codes represent the same base language, ignoring regional and script differences.
This is useful for determining language compatibility and grouping content by language family.

---

## Reference

### Parameters

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

### Returns

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

---

## Examples

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


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

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

// Base language with variants
console.log(gt.isSameLanguage('en', 'en-US', 'en-GB')); // true
```

---

## Notes

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

## Next steps

- **[Compare dialects with isSameDialect](/docs/core/class/methods/locales/is-same-dialect)**
- **[Check locale hierarchy with isSupersetLocale](/docs/core/class/methods/locales/is-superset-locale)**