Version: 2.0.0-beta.15 🚧

Docusaurus Client API

Docusaurus provides some APIs on the clients that can be helpful to you when building your site.

Components

`<ErrorBoundary />`

This component creates a React error boundary.

Use it to wrap components that might throw, and display a fallback when that happens instead of crashing the whole app.

import React from 'react';
import ErrorBoundary from '@docusaurus/ErrorBoundary';

const SafeComponent = () => (
  <ErrorBoundary
    fallback={({error, tryAgain}) => (
      <div>
        <p>This component crashed because of error: {error.message}.</p>
        <button onClick={tryAgain}>Try Again!</button>
      </div>
    )}>
    <SomeDangerousComponentThatMayThrow />
  </ErrorBoundary>
);

tip

To see it in action, click here:

info

Docusaurus uses this component to catch errors within the theme's layout, and also within the entire app.

note

This component doesn't catch build-time errors and only protects against client-side render errors that can happen when using stateful React components.

Props

fallback: an optional callback returning a JSX element. It will receive two props: error, the error that was caught, and tryAgain, a function (() => void) callback to reset the error in the component and try rendering it again.

`<Head/>`

This reusable React component will manage all of your changes to the document head. It takes plain HTML tags and outputs plain HTML tags and is beginner-friendly. It is a wrapper around React Helmet.

Usage Example:

import React from 'react';
import Head from '@docusaurus/Head';

const MySEO = () => (
  <Head>
    <meta property="og:description" content="My custom description" />
    <meta charSet="utf-8" />
    <title>My Title</title>
    <link rel="canonical" href="http://mysite.com/example" />
  </Head>
);

Nested or latter components will override duplicate usages:

<Parent>
  <Head>
    <title>My Title</title>
    <meta name="description" content="Helmet application" />
  </Head>
  <Child>
    <Head>
      <title>Nested Title</title>
      <meta name="description" content="Nested component" />
    </Head>
  </Child>
</Parent>

Outputs:

<head>
  <title>Nested Title</title>
  <meta name="description" content="Nested component" />
</head>

`<Link/>`

This component enables linking to internal pages as well as a powerful performance feature called preloading. Preloading is used to prefetch resources so that the resources are fetched by the time the user navigates with this component. We use an IntersectionObserver to fetch a low-priority request when the <Link> is in the viewport and then use an onMouseOver event to trigger a high-priority request when it is likely that a user will navigate to the requested resource.

The component is a wrapper around react-router’s <Link> component that adds useful enhancements specific to Docusaurus. All props are passed through to react-router’s <Link> component.

External links also work, and automatically have these props: target="_blank" rel="noopener noreferrer".

import React from 'react';
import Link from '@docusaurus/Link';

const Page = () => (
  <div>
    <p>
      Check out my <Link to="/blog">blog</Link>!
    </p>
    <p>
      Follow me on <Link to="https://twitter.com/docusaurus">Twitter</Link>!
    </p>
  </div>
);

`to`: string

The target location to navigate to. Example: /docs/introduction.

<Link to="/courses" />

tip

Prefer this component to vanilla <a> tags because Docusaurus does a lot of optimizations (e.g. broken path detection, prefetching, applying base URL...) if you use <Link>.

`<Redirect/>`

Rendering a <Redirect> will navigate to a new location. The new location will override the current location in the history stack like server-side redirects (HTTP 3xx) do. You can refer to React Router's Redirect documentation for more info on available props.

Example usage:

import React from 'react';
import {Redirect} from '@docusaurus/router';

const Home = () => {
  return <Redirect to="/docs/test" />;
};

note

@docusaurus/router implements React Router and supports its features.

`<BrowserOnly/>`

The <BrowserOnly> component permits to render React components only in the browser after the React app has hydrated.

tip

Use it for integrating with code that can't run in Node.js, because the window or document objects are being accessed.

Props

children: render function prop returning browser-only JSX. Will not be executed in Node.js
fallback (optional): JSX to render on the server (Node.js) and until React hydration completes.

Example with code

import BrowserOnly from '@docusaurus/BrowserOnly';

const MyComponent = () => {
  return (
    <BrowserOnly>
      {() => <span>page url = {window.location.href}</span>}
    </BrowserOnly>
  );
};

Example with a library

import BrowserOnly from '@docusaurus/BrowserOnly';

const MyComponent = (props) => {
  return (
    <BrowserOnly fallback={<div>Loading...</div>}>
      {() => {
        const LibComponent = require('some-lib').LibComponent;
        return <LibComponent {...props} />;
      }}
    </BrowserOnly>
  );
};

Why do we use a "render function"?

It's important to realize that the children of <BrowserOnly> is not a JSX element, but a function that returns an element. This is a design decision. Consider this code:

import BrowserOnly from '@docusaurus/BrowserOnly';

const MyComponent = () => {
  return (
    <BrowserOnly>
      {/* DON'T DO THIS - doesn't actually work */}
      <span>page url = {window.location.href}</span>
    </BrowserOnly>
  );
};

While you may expect that BrowserOnly hides away the children during server-side rendering, it actually can't. When the React renderer tries to render this JSX tree, it does see the {window.location.href} variable as a node of this tree and tries to render it, although it's actually not used! Using a function ensures that we only let the renderer see the browser-only component when it's needed.

`<Interpolate/>`

A simple interpolation component for text containing dynamic placeholders.

The placeholders will be replaced with the provided dynamic values and JSX elements of your choice (strings, links, styled elements...).

Props

children: text containing interpolation placeholders like {placeholderName}
values: object containing interpolation placeholder values

import React from 'react';
import Link from '@docusaurus/Link';
import Interpolate from '@docusaurus/Interpolate';

export default function VisitMyWebsiteMessage() {
  return (
    <Interpolate
      values={{
        firstName: 'Sébastien',
        website: (
          <Link to="https://docusaurus.io" className="my-website-class">
            website
          </Link>
        ),
      }}>
      {'Hello, {firstName}! How are you? Take a look at my {website}'}
    </Interpolate>
  );
}

`<Translate/>`

When localizing your site, the <Translate/> component will allow providing translation support to React components, such as your homepage. The <Translate> component supports interpolation.

The translation strings will statically extracted from your code with the docusaurus write-translations CLI and a code.json translation file will be created in website/i18n/[locale].

note

The <Translate/> props must be hardcoded strings.

Apart from the values prop used for interpolation, it is not possible to use variables, or the static extraction wouldn't work.

Props

children: untranslated string in the default site locale (can contain interpolation placeholders)
id: optional value to be used as the key in JSON translation files
description: optional text to help the translator
values: optional object containing interpolation placeholder values

Example

src/pages/index.js
import React from 'react';
import Layout from '@theme/Layout';

import Translate from '@docusaurus/Translate';

export default function Home() {
  return (
    <Layout>
      <h1>
        <Translate
          id="homepage.title"
          description="The homepage welcome message">
          Welcome to my website
        </Translate>
      </h1>
      <main>
        <Translate values={{firstName: 'Sébastien'}}>
          {'Welcome, {firstName}! How are you?'}
        </Translate>
      </main>
    </Layout>
  );
}

note

You can even omit the children prop and specify a translation string in your code.json file manually after running the docusaurus write-translations CLI command.

<Translate id="homepage.title" />

Hooks

`useDocusaurusContext`

React hook to access Docusaurus Context. The context contains the siteConfig object from docusaurus.config.js and some additional site metadata.

type DocusaurusPluginVersionInformation =
  | {readonly type: 'package'; readonly version?: string}
  | {readonly type: 'project'}
  | {readonly type: 'local'}
  | {readonly type: 'synthetic'};

interface DocusaurusSiteMetadata {
  readonly docusaurusVersion: string;
  readonly siteVersion?: string;
  readonly pluginVersions: Record<string, DocusaurusPluginVersionInformation>;
}

interface I18nLocaleConfig {
  label: string;
  direction: string;
}

interface I18n {
  defaultLocale: string;
  locales: [string, ...string[]];
  currentLocale: string;
  localeConfigs: Record<string, I18nLocaleConfig>;
}

interface DocusaurusContext {
  siteConfig: DocusaurusConfig;
  siteMetadata: DocusaurusSiteMetadata;
  globalData: Record<string, unknown>;
  i18n: I18n;
  codeTranslations: Record<string, string>;
}

Usage example:

import React from 'react';
import useDocusaurusContext from '@docusaurus/useDocusaurusContext';

const MyComponent = () => {
  const {siteConfig, siteMetadata} = useDocusaurusContext();
  return (
    <div>
      <h1>{siteConfig.title}</h1>
      <div>{siteMetadata.siteVersion}</div>
      <div>{siteMetadata.docusaurusVersion}</div>
    </div>
  );
};

note

The siteConfig object only contains serializable values (values that are preserved after JSON.stringify()). Functions, regexes, etc. would be lost on the client side.

`useIsBrowser`

Returns true when the React app has successfully hydrated in the browser.

caution

Use this hook instead of typeof windows !== 'undefined' in React rendering logic.

The first client-side render output (in the browser) must be exactly the same as the server-side render output (Node.js). Not following this rule can lead to unexpected hydration behaviors, as described in The Perils of Rehydration.

Usage example:

import React from 'react';
import useIsBrowser from '@docusaurus/useIsBrowser';

const MyComponent = () => {
  const isBrowser = useIsBrowser();
  return <div>{isBrowser ? 'Client' : 'Server'}</div>;
};

`useBaseUrl`

React hook to prepend your site baseUrl to a string.

caution

Don't use it for regular links!

The /baseUrl/ prefix is automatically added to all absolute paths by default:

Markdown: [link](/my/path) will link to /baseUrl/my/path
React: <Link to="/my/path/">link</Link> will link to /baseUrl/my/path

Options

type BaseUrlOptions = {
  forcePrependBaseUrl: boolean;
  absolute: boolean;
};

Example usage:

import React from 'react';
import useBaseUrl from '@docusaurus/useBaseUrl';

const SomeImage = () => {
  const imgSrc = useBaseUrl('/img/myImage.png');
  return <img src={imgSrc} />;
};

tip

In most cases, you don't need useBaseUrl.

Prefer a require() call for assets:

<img src={require('@site/static/img/myImage.png').default} />

`useBaseUrlUtils`

Sometimes useBaseUrl is not good enough. This hook return additional utils related to your site's base url.

withBaseUrl: useful if you need to add base URLs to multiple URLs at once.

import React from 'react';
import {useBaseUrlUtils} from '@docusaurus/useBaseUrl';

const Component = () => {
  const urls = ['/a', '/b'];
  const {withBaseUrl} = useBaseUrlUtils();
  const urlsWithBaseUrl = urls.map(withBaseUrl);
  return <div>{/* ... */}</div>;
};

`useGlobalData`

React hook to access Docusaurus global data created by all the plugins.

Global data is namespaced by plugin name then by plugin ID.

info

Plugin ID is only useful when a plugin is used multiple times on the same site. Each plugin instance is able to create its own global data.

type GlobalData = Record<
  PluginName,
  Record<
    PluginId, // "default" by default
    any // plugin-specific data
  >
>;

Usage example:

import React from 'react';
import useGlobalData from '@docusaurus/useGlobalData';

const MyComponent = () => {
  const globalData = useGlobalData();
  const myPluginData = globalData['my-plugin']['default'];
  return <div>{myPluginData.someAttribute}</div>;
};

tip

Inspect your site's global data at ./docusaurus/globalData.json

`usePluginData`

Access global data created by a specific plugin instance.

This is the most convenient hook to access plugin global data and should be used most of the time.

pluginId is optional if you don't use multi-instance plugins.

function usePluginData(pluginName: string, pluginId?: string);

Usage example:

import React from 'react';
import {usePluginData} from '@docusaurus/useGlobalData';

const MyComponent = () => {
  const myPluginData = usePluginData('my-plugin');
  return <div>{myPluginData.someAttribute}</div>;
};

`useAllPluginInstancesData`

Access global data created by a specific plugin. Given a plugin name, it returns the data of all the plugins instances of that name, by plugin id.

useAllPluginInstancesData(pluginName: string)

Usage example:

import React from 'react';
import {useAllPluginInstancesData} from '@docusaurus/useGlobalData';

const MyComponent = () => {
  const allPluginInstancesData = useAllPluginInstancesData('my-plugin');
  const myPluginData = allPluginInstancesData['default'];
  return <div>{myPluginData.someAttribute}</div>;
};

Functions

`interpolate`

The imperative counterpart of the <Interpolate> component.

Signature

// Simple string interpolation
function interpolate(text: string, values: Record<string, string>): string;

// JSX interpolation
function interpolate(
  text: string,
  values: Record<string, ReactNode>,
): ReactNode;

Example

import {interpolate} from '@docusaurus/Interpolate';

const message = interpolate('Welcome {firstName}', {firstName: 'Sébastien'});

`translate`

The imperative counterpart of the <Translate> component. Also supporting placeholders interpolation.

tip

Use the imperative API for the rare cases where a component cannot be used, such as:

the page title metadata
the placeholder props of form inputs
the aria-label props for accessibility

Signature

function translate(
  translation: {message: string; id?: string; description?: string},
  values: Record<string, string>,
): string;

Example

src/pages/index.js
import React from 'react';
import Layout from '@theme/Layout';

import {translate} from '@docusaurus/Translate';

export default function Home() {
  return (
    <Layout
      title={translate({message: 'My page meta title'})}>
      <img
        src={'https://docusaurus.io/logo.png'}
        aria-label={
          translate(
            {
              message: 'The logo of site {siteName}',
              // Optional
              id: 'homepage.logo.ariaLabel',
              description: 'The home page logo aria label',
            },
            {siteName: 'Docusaurus'},
          )
        }
      />
    </Layout>
  );
}

Modules

`ExecutionEnvironment`

A module that exposes a few boolean variables to check the current rendering environment.

caution

For React rendering logic, use useIsBrowser() or <BrowserOnly> instead.

Example:

import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';

if (ExecutionEnvironment.canUseDOM) {
  require('lib-that-only-works-client-side');
}

Field	Description
`ExecutionEnvironment.canUseDOM`	`true` if on client/browser, `false` on Node.js/prerendering.
`ExecutionEnvironment.canUseEventListeners`	`true` if on client and has `window.addEventListener`.
`ExecutionEnvironment.canUseIntersectionObserver`	`true` if on client and has `IntersectionObserver`.
`ExecutionEnvironment.canUseViewport`	`true` if on client and has `window.screen`.

`constants`

A module exposing useful constants to client-side theme code.

import {DEFAULT_PLUGIN_ID} from '@docusaurus/constants';

Named export	Value
`DEFAULT_PLUGIN_ID`	`default`

Components​

<ErrorBoundary />​

tip

info

note

Props​

<Head/>​

<Link/>​

to: string​

tip

<Redirect/>​

note

<BrowserOnly/>​

tip

Props​

Example with code​

Example with a library​

Why do we use a "render function"?

<Interpolate/>​

Props​

<Translate/>​

note

Props​

Example​

note

Hooks​

useDocusaurusContext​

note

useIsBrowser​

caution

useBaseUrl​

caution

Options​

Example usage:​

tip

useBaseUrlUtils​

useGlobalData​

info

tip

usePluginData​

useAllPluginInstancesData​

Functions​

interpolate​

Signature​

Example​

translate​

tip

Signature​

Example​

Modules​

ExecutionEnvironment​

caution

constants​

Components

`<ErrorBoundary />`

Props

`<Head/>`

`<Link/>`

`to`: string

`<Redirect/>`

`<BrowserOnly/>`

Props

Example with code

Example with a library

`<Interpolate/>`

Props

`<Translate/>`

Props

Example

Hooks

`useDocusaurusContext`

`useIsBrowser`

`useBaseUrl`

Options

Example usage:

`useBaseUrlUtils`

`useGlobalData`

`usePluginData`

`useAllPluginInstancesData`

Functions

`interpolate`

Signature

Example

`translate`

Signature

Example

Modules

`ExecutionEnvironment`

`constants`