### Example configuration for testing without stubbing

Source: https://react.i18next.com/misc/testing.md

This i18next configuration initializes i18next with a test setup, including a common namespace and empty resources. It is used to test components without stubbing, by providing a real i18n instance to the provider.

```javascript
import i18n from 'i18next';
import { initReactI18next } from 'react-i18next';

i18n
  .use(initReactI18next)
  .init({
    lng: 'en',
    fallbackLng: 'en',

    // have a common namespace used around the full app
    ns: ['translationsNS'],
    defaultNS: 'translationsNS',

    debug: true,

    interpolation: {
      escapeValue: false, // not needed for react!!
    },

    resources: { en: { translationsNS: {} } },
  });

export default i18n;
```

--------------------------------

### npm install react-i18next i18next and optional backends

Source: https://react.i18next.com/latest/using-with-hooks.md

Install react-i18next and i18next packages, and optionally i18next-http-backend and i18next-browser-languagedetector for user language detection and loading translations.

```bash
npm install react-i18next i18next --save

# if you'd like to detect user language and load translation
npm install i18next-http-backend i18next-browser-languagedetector --save
```

--------------------------------

### HTTP GET request with ask and goal parameters

Source: https://react.i18next.com/llms.txt

Use this HTTP GET request to ask a question about the documentation. The `ask` parameter is required and should be a specific, self-contained natural language question; `goal` is optional and describes the broader end goal. The response contains a direct answer with relevant excerpts and sources.

```http
GET https://react.i18next.com/latest/typescript.md?ask=<question>&goal=<end_goal>
```

--------------------------------

### Install react-i18next and i18next with npm

Source: https://react.i18next.com/getting-started.md

Use this command to install both react-i18next and i18next as dependencies. The module is optimized for webpack and rollup, with correct entry points already configured in package.json.

```bash
# npm
$ npm install react-i18next i18next --save
```

--------------------------------

### Using simple HTML elements in Trans (v10.4.0)

Source: https://react.i18next.com/latest/trans-component.md

Shows examples with strong, br, and Link component, with corresponding JSON translation strings.

```jsx
<Trans i18nKey="welcomeUser">
  Hello <strong>{{name}}</strong>. <Link to="/inbox">See my profile</Link>
</Trans>
// JSON -> "welcomeUser": "Hello <strong>{{name}}</strong>. <1>See my profile</1>"

<Trans i18nKey="multiline">
  Some newlines <br/> would be <br/> fine
</Trans>
// JSON -> "multiline": "Some newlines <br/> would be <br/> fine"
```

--------------------------------

### Trans component example

Source: https://react.i18next.com/guides/quick-start.md

Use the Trans component to translate a JSX tree, allowing translation of text containing components like links or formatting. The example shows a component and the corresponding translation key.

```jsx
import React from 'react';
import { Trans } from 'react-i18next';

export default function MyComponent () {
  return <Trans><H1>Welcome to React</H1></Trans>
}

// the translation in this case should be
"<0>Welcome to React</0>": "<0>Welcome to React and react-i18next</0>"
```

--------------------------------

### Basic i18n setup with react-i18next (TypeScript)

Source: https://react.i18next.com/getting-started.md

Same as the JavaScript version but written in TypeScript. The translation key is accessed using the syntax `t($ => $['Welcome to React'])` instead of `t('Welcome to React')`.

```tsx
import React from "react";
import { createRoot } from 'react-dom/client';
import i18n from "i18next";
import { useTranslation, initReactI18next } from "react-i18next";

i18n
  .use(initReactI18next) // passes i18n down to react-i18next
  .init({
    // the translations
    // (tip move them in a JSON file and import them,
    // or even better, manage them via a UI: https://react.i18next.com/guides/multiple-translation-files#manage-your-translations-with-a-management-gui)
    resources: {
      en: {
        translation: {
          "Welcome to React": "Welcome to React and react-i18next"
        }
      }
    },
    lng: "en", // if you're using a language detector, do not define the lng option
    fallbackLng: "en",

    interpolation: {
      escapeValue: false // react already safes from xss => https://www.i18next.com/translation-function/interpolation#unescape
    }
  });

function App() {
  const { t } = useTranslation();

  return <h2>{t($ => $['Welcome to React'])}</h2>;
}

// append app to dom
const root = createRoot(document.getElementById('root'));
root.render(
  <App />
);
```

--------------------------------

### Babel macro setup commands for create-react-app

Source: https://react.i18next.com/misc/using-with-icu-format.md

Commands to set up babel-plugin-macros: create a new app with npx create-react-app, or upgrade an existing app with yarn upgrade react-scripts@2. The macro plugin is included in react-scripts v2.

```shell
$ # Create a new application
$ npx create-react-app
$ # Upgrade an existing application
$ yarn upgrade react-scripts@2
```

--------------------------------

### Using I18nextProvider with i18n and defaultNS

Source: https://react.i18next.com/latest/i18nextprovider.md

Wrap your App with I18nextProvider, passing the i18n instance and optionally defaultNS to manage default namespaces. Required for multiple i18next instances or SSR setups.

```jsx
import { I18nextProvider } from 'react-i18next';
import i18n from './i18n';
import App from './App';

<I18nextProvider i18n={i18n} defaultNS={'translation'}>
  <App />
</I18nextProvider>
```

--------------------------------

### JSX tree before translation

Source: https://react.i18next.com/getting-started.md

Example of React code before using the Trans component, showing hardcoded content with HTML formatting and components.

```jsx
<div>
  Hello <strong title="this is your name">{name}</strong>, you have {count} unread message(s). <Link to="/msgs">Go to messages</Link>.
</div>
```

--------------------------------

### Change language with i18n instance

Source: https://react.i18next.com/latest/translation-render-prop.md

Example of using the i18n instance obtained from the Translation render prop to change the language.

```javascript
i18n.changeLanguage('en-US');
```

--------------------------------

### Example test using this configuration

Source: https://react.i18next.com/misc/testing.md

This test renders a component wrapped in I18nextProvider with the test i18n instance, and uses redux-mock-store to simulate a store. It verifies that clicking a sort button dispatches the SORT_TABLE action.

```javascript
import React from 'react';
import { Provider } from 'react-redux';
import { render, fireEvent } from '@testing-library/react';
import { I18nextProvider } from 'react-i18next';
import configureStore from 'redux-mock-store';
import ContactTable from './ContactTable';
import actionTypes from '../constants';
import i18n from '../i18nForTests';

const mockStore = configureStore([]);
const store = mockStore({ contacts: [ ] });

it('dispatches SORT_TABLE', () => {
  const { container } = render(
    <Provider store={store}>
      <I18nextProvider i18n={i18n}>
        <ContactTable />
      </I18nextProvider>
    </Provider>
  );
  fireEvent.click(container.querySelector('.sort'));
  const actions = store.getActions();
  expect(actions).toEqual([{ type: actionTypes.SORT_TABLE }]);
});
```

--------------------------------

### JSX tree after using Trans component (TypeScript)

Source: https://react.i18next.com/getting-started.md

TypeScript version of the Trans component example, using a selector callback for the title attribute.

```tsx
<Trans i18nKey="userMessagesUnread" count={count}>
  Hello <strong title={t($ => $.nameTitle)}>{{name}}</strong>, you have {{count}} unread message. <Link to="/msgs">Go to messages</Link>.
</Trans>
```

--------------------------------

### Translation string with numbered placeholders

Source: https://react.i18next.com/guides/the-drawbacks-of-other-i18n-solutions.md

Example of a translation string that keeps the mixed JSX as one sentence using numbered placeholders. This is the format that the Trans component can handle.

```text
Hello <1>{name}</1>, you have <3>{count} unread message(s)</3>.
```

--------------------------------

### Trans component example

Source: https://react.i18next.com/latest/using-with-hooks.md

Use the Trans component to translate a JSX tree, allowing translation of text containing components like <strong>. The translation key includes numbered placeholders.

```jsx
import React from 'react';
import { Trans } from 'react-i18next';

export default function MyComponent () {
  return <Trans>Welcome to <strong>React</strong></Trans>
}

// the translation in this case should be
"Welcome to <1>React</1>": "Welcome to <1>React and react-i18next</1>"
```

--------------------------------

### More samples of babel macro Trans usage

Source: https://react.i18next.com/misc/using-with-icu-format.md

Examples of using the Trans macro for basic interpolation, interpolation with components, number formatting, date formatting, and a link with number formatting. Each sample shows a JSX usage and a defaults variant for translation keys.

```jsx
// basic interpolation
<Trans>Welcome, { name }!</Trans>

// interpolation and components
<Trans>Welcome, <strong>{ name }</strong>!</Trans>
<Trans defaults="Welcome, <strong>{ name }</strong>" />

// number formatting
<Trans>Trainers: { trainersCount, number }</Trans>
<Trans>Trainers: <strong>{ trainersCount, number }</strong>!</Trans>
<Trans defaults="Trainers: <strong>{ trainersCount, number }</strong>!" />

// date formatting
<Trans>Caught on { catchDate, date, short }</Trans>
<Trans>Caught on <strong>{ catchDate, date, short }</strong>!</Trans>
<Trans defaults="Caught on <strong>{ catchDate, date, short }</strong>!" />

<Trans>You have <Link to="/inbox">{ unread, number } messages</Link></Trans>
<Trans defaults="You have <Link to='/inbox'>{ unread, number } messages</Link>" />
```

--------------------------------

### Basic i18n setup with react-i18next (JavaScript)

Source: https://react.i18next.com/getting-started.md

Initializes i18next with react-i18next, defines English translations, and uses the useTranslation hook in a React component. The lng option is set to 'en' and fallbackLng to 'en'. Interpolation escaping is disabled because React already handles XSS safety.

```jsx
import React from "react";
import { createRoot } from 'react-dom/client';
import i18n from "i18next";
import { useTranslation, initReactI18next } from "react-i18next";

i18n
  .use(initReactI18next) // passes i18n down to react-i18next
  .init({
    // the translations
    // (tip move them in a JSON file and import them,
    // or even better, manage them via a UI: https://react.i18next.com/guides/multiple-translation-files#manage-your-translations-with-a-management-gui)
    resources: {
      en: {
        translation: {
          "Welcome to React": "Welcome to React and react-i18next"
        }
      }
    },
    lng: "en", // if you're using a language detector, do not define the lng option
    fallbackLng: "en",

    interpolation: {
      escapeValue: false // react already safes from xss => https://www.i18next.com/translation-function/interpolation#unescape
    }
  });

function App() {
  const { t } = useTranslation();

  return <h2>{t('Welcome to React')}</h2>;
}

// append app to dom
const root = createRoot(document.getElementById('root'));
root.render(
  <App />
);
```

--------------------------------

### Using babel macro Trans for ICU and Trans

Source: https://react.i18next.com/misc/using-with-icu-format.md

Example of using the Trans macro from 'react-i18next/icu.macro'. The macro adds the needed import for IcuTrans and generates the correct component for you. The translation string is output to console if debug is true or submitted via saveMissing, if enabled.

```javascript
import { Trans } from 'react-i18next/icu.macro';

const user = 'John Doe';

<Trans i18nKey="icu_and_trans">
  We invited <strong>{user}</strong>.
</Trans>
```

--------------------------------

### JSX with mixed nodes for translation

Source: https://react.i18next.com/guides/the-drawbacks-of-other-i18n-solutions.md

Example of JSX content that combines text and components. It illustrates the challenge of translating mixed JSX nodes in a single sentence, which most frameworks require splitting into multiple translation strings.

```javascript
<p>
  Hello <strong>{name}</strong>, you have 
  <Link to="/msgs">{count} unread message(s)</Link>.
</p>
```

--------------------------------

### Spy on t function with jest.fn (TypeScript)

Source: https://react.i18next.com/misc/testing.md

TypeScript version of the spy example, using a typed t function with interpolation.

```tsx
// implementation
import React from 'react';
import { useTranslation } from 'react-i18next';

export default function CustomComponent() {
  const { t } = useTranslation();

  return <div>{t($ => $.some.key, { some: 'variable' })}</div>;
}

// test
import React from 'react';
import { render, screen } from '@testing-library/react';
import UseTranslationWithInterpolation from './UseTranslationWithInterpolation';
import { useTranslation } from 'react-i18next';

jest.mock('react-i18next', () => ({
  useTranslation: jest.fn(),
}));
```

--------------------------------

### Configure i18next instance with backend, language detector, and initReactI18next

Source: https://react.i18next.com/latest/i18next-instance.md

Initializes the i18next instance with a backend for loading translations from the server, a language detector, and binds react-i18next. Sets fallback language to 'en', enables debug mode, and disables interpolation escaping for React. Includes commented-out optional react-specific options.

```javascript
import i18n from 'i18next';
import Backend from 'i18next-http-backend';
import LanguageDetector from 'i18next-browser-languagedetector';
import { initReactI18next } from 'react-i18next';


i18n
  .use(Backend)
  .use(LanguageDetector)
  .use(initReactI18next) // bind react-i18next to the instance
  .init({
    fallbackLng: 'en',
    debug: true,

    interpolation: {
      escapeValue: false, // not needed for react!!
    },

    // react i18next special options (optional)
    // override if needed - omit if ok with defaults
    /*
    react: {
      bindI18n: 'languageChanged',
      bindI18nStore: '',
      transEmptyNodeValue: '',
      transSupportBasicHtmlNodes: true,
      transKeepBasicHtmlNodesFor: ['br', 'strong', 'i'],
      useSuspense: true,
    }
    */
  });


export default i18n;
```

--------------------------------

### Overriding component props with listed components (v11.5.0) - JSX example

Source: https://react.i18next.com/latest/trans-component.md

Alternative method using array for components prop.

```javascript
<Trans
  i18nKey="myKey"
  components={[ <MyCustomLinkComponent href="value-to-be-overridden"/> ]}
/>
```

--------------------------------

### withTranslation HOC in TypeScript

Source: https://react.i18next.com/latest/using-with-hooks.md

TypeScript version of the withTranslation HOC example. Uses the t function with a callback syntax for type-safe translation keys.

```tsx
import React, { Component, Suspense } from 'react';
import { withTranslation } from 'react-i18next';

class LegacyComponentClass extends Component {
  render() {
    const { t } = this.props;

    return (
      <h1>{t($ => $['Welcome to React'])}</h1>
    )
  }
}
const MyComponent = withTranslation()(LegacyComponentClass)

// i18n translations might still be loaded by the http backend
// use react's Suspense
export default function App() {
  return (
    <Suspense fallback="loading">
      <MyComponent />
    </Suspense>
  );
}
```

--------------------------------

### Configure i18next in i18n.js with hooks

Source: https://react.i18next.com/latest/using-with-hooks.md

Create i18n.js beside index.js to initialize i18next with backend, language detector, and react-i18next. Sets fallback language to 'en' and disables escaping for React.

```javascript
import i18n from 'i18next';
import { initReactI18next } from 'react-i18next';

import Backend from 'i18next-http-backend';
import LanguageDetector from 'i18next-browser-languagedetector';
// don't want to use this?
// have a look at the Quick start guide 
// for passing in lng and translations on init

i18n
  // load translation using http -> see /public/locales (i.e. https://github.com/i18next/react-i18next/tree/master/example/react/public/locales)
  // learn more: https://github.com/i18next/i18next-http-backend
  // want your translations to be loaded from a professional CDN? => https://github.com/locize/react-tutorial#step-2---use-the-locize-cdn
  .use(Backend)
  // detect user language
  // learn more: https://github.com/i18next/i18next-browser-languageDetector
  .use(LanguageDetector)
  // pass the i18n instance to react-i18next.
  .use(initReactI18next)
  // init i18next
  // for all options read: https://www.i18next.com/overview/configuration-options
  .init({
    fallbackLng: 'en',
    debug: true,

    interpolation: {
      escapeValue: false, // not needed for react as it escapes by default
    }
  });


export default i18n;
```

--------------------------------

### useTranslation hook in TypeScript

Source: https://react.i18next.com/latest/using-with-hooks.md

TypeScript version of the useTranslation hook example. Uses the t function with a callback syntax for type-safe translation keys.

```tsx
import React, { Suspense } from 'react';
import { useTranslation } from 'react-i18next';

function MyComponent() {
  const { t, i18n } = useTranslation();

  return <h1>{t($ => $['Welcome to React'])}</h1>
}

// i18n translations might still be loaded by the http backend
// use react's Suspense
export default function App() {
  return (
    <Suspense fallback="loading">
      <MyComponent />
    </Suspense>
  );
}
```

--------------------------------

### After: Using Trans component (JavaScript)

Source: https://react.i18next.com/latest/trans-component.md

Shows how to replace the untranslated code with the Trans component in JavaScript, using the i18nKey and count props.

```jsx
import { Trans } from 'react-i18next';

function MyComponent({ person, messages }) {
  const { name } = person;
  const count = messages.length;

  return (
    <Trans i18nKey="userMessagesUnread" count={count}>
      Hello <strong title={t('nameTitle')}>{{name}}</strong>, you have {{count}} unread message. <Link to="/msgs">Go to messages</Link>.
    </Trans>
  );
}
```

--------------------------------

### Using i18next directly in React (JavaScript and TypeScript)

Source: https://react.i18next.com/guides/the-drawbacks-of-other-i18n-solutions.md

Shows how to use the i18next framework directly in a React component. The JavaScript version uses i18n.t('welcome') while the TypeScript version uses i18n.t($ => $.welcome). Both initialize i18next with a translation catalog and render a simple welcome message.

```jsx
import React, { Component } from "react";
import { createRoot } from 'react-dom/client';
import i18n from "i18next";

// translation catalog
const resources = {
  en: {
    translation: {
      "welcome": "Welcome to React and react-i18next"
    }
  }
};

// initialize i18next with catalog and language to use
i18n.init({
  resources,
  lng: "en"
});

class App extends Component {
  render() {
    return <h2>{i18n.t('welcome')}</h2>;
  }
}

// append app to dom
const root = createRoot(document.getElementById('root'));
root.render(
  <App />
);
```

```tsx
import React, { Component } from "react";
import { createRoot } from 'react-dom/client';
import i18n from "i18next";

// translation catalog
const resources = {
  en: {
    translation: {
      "welcome": "Welcome to React and react-i18next"
    }
  }
};

// initialize i18next with catalog and language to use
i18n.init({
  resources,
  lng: "en"
});

class App extends Component {
  render() {
    return <h2>{i18n.t($ => $.welcome)}</h2>;
  }
}

// append app to dom
const root = createRoot(document.getElementById('root'));
root.render(
  <App />
);
```

--------------------------------

### Overriding component props with Trans (v11.5.0) - JSX example

Source: https://react.i18next.com/latest/trans-component.md

Uses Trans with custom component and href to override based on active language.

```javascript
<Trans
  i18nKey="myKey"
  components={{ 
    CustomLink: <MyCustomLinkComponent href="value-to-be-overridden"/> 
  }}
/>
```

--------------------------------

### Create i18n.js configuration

Source: https://react.i18next.com/guides/quick-start.md

Initializes i18next with react-i18next, defines translation resources for English and French, and sets the default language to 'en'. The file can be named anything as long as it is imported correctly.

```javascript
import i18n from "i18next";
import { initReactI18next } from "react-i18next";

// the translations
// (tip move them in a JSON file and import them,
// or even better, manage them separated from your code: https://react.i18next.com/guides/multiple-translation-files)
const resources = {
  en: {
    translation: {
      "Welcome to React": "Welcome to React and react-i18next"
    }
  },
  fr: {
    translation: {
      "Welcome to React": "Bienvenue à React et react-i18next"
    }
  }
};

i18n
  .use(initReactI18next) // passes i18n down to react-i18next
  .init({
    resources,
    lng: "en", // language to use, more information here: https://www.i18next.com/overview/configuration-options#languages-namespaces-resources
    // you can use the i18n.changeLanguage function to change the language manually: https://www.i18next.com/overview/api#changelanguage
    // if you're using a language detector, do not define the lng option

    interpolation: {
      escapeValue: false // react already safes from xss
    }
  });

  export default i18n;
```

--------------------------------

### useTranslation hook in JavaScript

Source: https://react.i18next.com/guides/quick-start.md

Use the useTranslation hook in a functional component to get the t function and i18n instance. The t function is the main translation function in i18next.

```jsx
import React from 'react';

// the hook
import { useTranslation } from 'react-i18next';

function MyComponent () {
  const { t, i18n } = useTranslation();
  return <h1>{t('Welcome to React')}</h1>
}
```

--------------------------------

### Use useTranslation hook in functional component

Source: https://react.i18next.com/latest/migrating-v9-to-v10.md

Shows the new hook-based API in v10 for functional components. Use `useTranslation` to get the `t` function and the `i18n` instance.

```jsx
import React from 'react';
import { useTranslation } from 'react-i18next';

export function MyComponent() {
  const [t, i18n] = useTranslation();

  return <p>{t('my translated text')}</p>
}
```

--------------------------------

### Translation file sample

Source: https://react.i18next.com/latest/using-with-hooks.md

Sample content for a translation file located at public/locales/<language_code>/translation.json. It contains a title and a nested description object.

```json
{
  "title": "Welcome to react using react-i18next",
  "description": {
    "part1": "To get started, edit <1>src/App.js</1> and save to reload.",
    "part2": "Switch language between english and german using buttons above."
  }
}
```

--------------------------------

### Spy on t function with jest.fn (JavaScript)

Source: https://react.i18next.com/misc/testing.md

Spy on the t function using jest.fn to verify calls and arguments in tests. This example shows a component using useTranslation with interpolation and its test.

```jsx
// implementation
import React from 'react';
import { useTranslation } from 'react-i18next';

export default function CustomComponent() {
  const { t } = useTranslation();

  return <div>{t('some.key', { some: 'variable' })}</div>;
}

// test
import React from 'react';
import { render, screen } from '@testing-library/react';
import UseTranslationWithInterpolation from './UseTranslationWithInterpolation';
import { useTranslation } from 'react-i18next';

jest.mock('react-i18next', () => ({
  useTranslation: jest.fn(),
}));

it('test render', () => {
  const useTranslationSpy = useTranslation;
  const tSpy = jest.fn((str) => str);
  useTranslationSpy.mockReturnValue({
    t: tSpy,
    i18n: {
      changeLanguage: () => new Promise(() => {}),
    },
  });

  render(<UseTranslationWithInterpolation />);

  expect(screen.getByText('some.key')).toBeInTheDocument();

  // If you want you can also check how the t function has been called,
  // but basically this is testing your mock and not the actual code.
  expect(tSpy).toHaveBeenCalledTimes(1);
  expect(tSpy).toHaveBeenLastCalledWith('some.key', { some: 'variable' });
});
```

--------------------------------

### After: Using Trans component (TypeScript)

Source: https://react.i18next.com/latest/trans-component.md

Shows how to replace the untranslated code with the Trans component in TypeScript, using the i18nKey and count props.

```tsx
import { Trans } from 'react-i18next';

function MyComponent({ person, messages }) {
  const { name } = person;
  const count = messages.length;

  return (
    <Trans i18nKey="userMessagesUnread" count={count}>
      Hello <strong title={t($ => $.nameTitle)}>{{name}}</strong>, you have {{count}} unread message. <Link to="/msgs">Go to messages</Link>.
    </Trans>
  );
}
```

--------------------------------

### After: Using Trans component with semantic keys (JavaScript)

Source: https://react.i18next.com/

Shows the updated JSX using the Trans component with semantic i18n keys and interpolation for name and count.

```jsx
...
<div>{t('simpleContent')}</div>
<Trans i18nKey="userMessagesUnread" count={count}>
  Hello <strong title={t('nameTitle')}>{{name}}</strong>, you have {{count}} unread message(s). <Link to="/msgs">Go to messages</Link>.
</Trans>
...
```

--------------------------------

### Manual jest mock for react-i18next

Source: https://react.i18next.com/misc/testing.md

Create a manual mock in __mocks__/react-i18next.js that covers useTranslation, withTranslation, and Trans, so components mixing all three render keys and children as plain text.

```jsx
const React = require('react');
const reactI18next = require('react-i18next');

const useMock = [(k) => k, { changeLanguage: () => new Promise(() => {}) }];
useMock.t = (k) => k;
useMock.i18n = { changeLanguage: () => new Promise(() => {}) };

module.exports = {
  ...reactI18next,
  withTranslation: () => (Component) => (props) => <Component t={(k) => k} {...props} />,
  Trans: ({ children, i18nKey }) => children ?? i18nKey,
  useTranslation: () => useMock,
};
```

--------------------------------

### Access translation from default namespace with i18next.t (TypeScript)

Source: https://react.i18next.com/guides/multiple-translation-files.md

Accesses a translation key from the default namespace using i18next.t with a type-safe callback syntax. This is the TypeScript variant of the JavaScript example.

```tsx
i18next.t($ => $.look.deep);
```

--------------------------------

### Translation strings in en.json

Source: https://react.i18next.com/latest/icu-trans-component.md

The translation JSON needed for the IcuTrans example. It contains the nameTitle string and the pluralized userMessagesUnread keys (one/other) with ICU placeholders matching the defaultTranslation format.

```json
"nameTitle": "This is your name",
"userMessagesUnread_one": "Hello <1>{{name}}</1>, you have {{count}} unread message. <5>Go to message</5>.",
"userMessagesUnread_other": "Hello <1>{{name}}</1>, you have {{count}} unread messages.  <5>Go to messages</5>.",
```

--------------------------------

### TypeScript error for non-string in select interpolation

Source: https://react.i18next.com/misc/using-with-icu-format.md

Demonstrates that the `select` tagged template will cause a TypeScript error if a non-string is interpolated. The example shows a number variable causing a type error.

```jsx
import { Trans, select } from "react-i18next/icu.macro";

// type error below - awesomePercentage must be a number
const notAString = 100;

<Trans i18nKey="number">
 {select`${notAString} oops { you have to pass in a string } other { oh well }`}
</Trans>
```

--------------------------------

### Format a number with a skeleton using ICU macro

Source: https://react.i18next.com/misc/using-with-icu-format.md

Shows how to use a number skeleton (e.g., `::percent`) with the `number` tagged template. The resulting translation string is `It's awesome {awesomePercentage, number, ::percent} of the time`.

```jsx
import { Trans, number } from "react-i18next/icu.macro";

const awesomePercentage = 100;

<Trans i18nKey="number">
 It's awesome {number`${awesomePercentage}, ::percent`} of the time
</Trans>
```

--------------------------------

### withTranslation HOC usage in JavaScript

Source: https://react.i18next.com/latest/withtranslation-hoc.md

Use withTranslation to inject t and i18n into a functional component. The HOC wraps the component and provides the t function for translations. This example shows the basic JavaScript usage.

```jsx
import React from 'react';
import { withTranslation } from 'react-i18next';

function MyComponent({ t, i18n }) {
  return <p>{t('my translated text')}</p>
}

export default withTranslation()(MyComponent);
```

--------------------------------

### After: IcuTrans component in TypeScript

Source: https://react.i18next.com/latest/icu-trans-component.md

TypeScript version of the IcuTrans example, identical to JavaScript except for the title prop uses t(($) => $.nameTitle) instead of t('nameTitle'). Demonstrates typing support for the content array.

```tsx
import { IcuTrans } from 'react-i18next';

function MyComponent({ person, messages }) {
  const { name } = person;
  const count = messages.length;

  return (
    <IcuTrans
      i18nKey="userMessagesUnread" // optional -> fallbacks to defaults if not provided
      defaultTranslation="hello <0>{{name}}</0>, you have {{count}} unread message. <1>Go to messages</1>."
      values={{ name, count }}
      content={[
        {
          type: "strong",
          props: {
            title: t(($) => $.nameTitle),
          },
        },
        {
          type: Link,
          props: {
            to: "/msgs",
          },
        },
      ]}
    />
  );
}
```