# Runtime API

Modern.js Doc exposes some runtime APIs, which is convenient for you to do some custom logic.

## usePageData

Get the data of the current page, and the return value is an object, which contains all the data of the current page.

```js
import { usePageData } from '@modern-js/doc-tools/runtime';

function MyComponent() {
  const pageData = usePageData();
  return <div>{pageData.page.title}</div>;
}
```

## useLang

Get the current language, the return value is a string, which is the current language.

```js
import { useLang } from '@modern-js/doc-tools/runtime';

function MyComponent() {
  const lang = useLang();
  // lang === 'zh-CN'
  return <div>{lang}</div>;
}
```

## useDark

Whether it is dark mode currently, the return value is a boolean value.

```js
import { useDark } from '@modern-js/doc-tools/runtime';

function MyComponent() {
  const dark = useDark();
  return <div>{dark}</div>;
}
```

## useI18n

import UseI18n from '../../fragments/useI18n';

<UseI18n />

## Router Hook

The framework internally uses and re-exports all APIs of `react-router-dom`, you can use it like this:

```ts
import { useLocation } from '@modern-js/doc-tools/runtime';

function MyComponent() {
  const location = useLocation();
  return <div>{location.pathname}</div>;
}
```