> Deprecated:
> Product subscription app extensions won't be supported as of December 3, 2025. You should migrate existing product subscription app extensions to [purchase options extensions](/docs/apps/build/purchase-options/purchase-options-extensions).


Access the merchant’s current locale (in [IETF format](https://en.wikipedia.org/wiki/IETF_language_tag)) to internationalize your extension content.


```ts?title: "JavaScript"

import {extend, Text} from '@shopify/admin-ui-extensions';

extend('Admin::Product::SubscriptionPlan::Add', (root, api) => {
  const {locale} = api;

  const text = root.createText(`My current locale is: ${locale.initialValue}`);

  locale.setOnChange((newLocale) => {
    text.updateText(`My current locale is: ${newLocale}`);
  });

  root.appendChild(text);
  root.mount();
});


```

```tsx?title: "React"

import React from 'react';
import {extend, render, useLocale, Text} from '@shopify/admin-ui-extensions-react';

function App() {
  const locale = useLocale();

  return <Text>{`My current locale is: ${locale}`}</Text>;
}

extend(
  'Admin::Product::SubscriptionPlan::Add',
  render(() => <App />),
);


```



## Props
optional = ?
<a name="LocaleApiContent"></a>


| Name | Type | Description |
| --- | --- | --- |
| initialValue | <code>string</code> | IETF-formatted locale at time of page load  |
| setOnChange | <code>(onChange: (locale: string) => void) => void</code> | Callback when user changes locale during runtime  |