feat(v2): Support swizzling TypeScript components (#2671)

* feat(v2): Support swizzling TypeScript components

* Add tsc --noEmit to tsc script in theme-classic

Now everything can pass the type checker! (although still a lot of any)

* Add tsconfig and types.d.ts to website

Improve developer experience.

As an example, I converted NotFound to tsx

* Apply type annotation suggestions

* Do not fallback to `getThemePath` if getTypeScriptThemePath is undefined

* Fix tsc

* Add module declaration for @theme-original/*

* Move babel cli to root package.json

.eslintignore

@@ -22,6 +22,7 @@ packages/docusaurus-plugin-debug/lib/
 packages/docusaurus-plugin-sitemap/lib/
 packages/docusaurus-plugin-ideal-image/lib/
 packages/docusaurus-plugin-ideal-image/copyUntypedFiles.js
+packages/docusaurus-theme-classic/lib/
 
 packages/docusaurus-1.x/.eslintrc.js
 packages/docusaurus-init/templates/facebook/.eslintrc.js

.gitignore

@@ -26,3 +26,4 @@ packages/docusaurus-plugin-content-pages/lib/
 packages/docusaurus-plugin-debug/lib/
 packages/docusaurus-plugin-sitemap/lib/
 packages/docusaurus-plugin-ideal-image/lib/
+packages/docusaurus-theme-classic/lib/

package.json

@@ -34,6 +34,7 @@
   },
   "devDependencies": {
     "@babel/core": "^7.9.0",
+    "@babel/cli": "^7.9.0",
     "@babel/plugin-proposal-nullish-coalescing-operator": "^7.8.3",
     "@babel/plugin-proposal-optional-chaining": "^7.9.0",
     "@babel/preset-typescript": "^7.9.0",
@@ -52,6 +53,7 @@
     "@types/lodash.pick": "^4.4.6",
     "@types/lodash.pickby": "^4.6.6",
     "@types/node": "^13.11.0",
+    "@types/prismjs": "^1.16.1",
     "@types/react": "^16.9.38",
     "@types/react-dev-utils": "^9.0.1",
     "@types/react-helmet": "^6.0.0",

packages/docusaurus-module-type-aliases/src/index.d.ts

@@ -37,10 +37,9 @@ declare module '@generated/routesChunkNames' {
   export default routesChunkNames;
 }
 
-declare module '@theme/*' {
-  const component: any;
-  export default component;
-}
+declare module '@theme/*';
+
+declare module '@theme-original/*';
 
 declare module '@docusaurus/*';
 

packages/docusaurus-theme-classic/babel.config.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+module.exports = {
+  presets: [['@babel/preset-typescript', {isTSX: true, allExtensions: true}]],
+};

packages/docusaurus-theme-classic/package.json

@@ -7,6 +7,11 @@
     "access": "public"
   },
   "license": "MIT",
+  "scripts": {
+    "tsc": "tsc --noEmit && yarn babel && yarn prettier",
+    "babel": "babel src -d lib --extensions \".tsx,.ts\" --copy-files",
+    "prettier": "prettier --config ../../.prettierrc --write \"**/*.{js,ts}\""
+  },
   "dependencies": {
     "@hapi/joi": "^17.1.1",
     "@mdx-js/mdx": "^1.5.8",
@@ -21,6 +26,9 @@
     "react-router-dom": "^5.1.2",
     "react-toggle": "^4.1.1"
   },
+  "devDependencies": {
+    "@docusaurus/module-type-aliases": "^2.0.0-alpha.58"
+  },
   "peerDependencies": {
     "@docusaurus/core": "^2.0.0",
     "react": "^16.8.4",

packages/docusaurus-theme-classic/src/index.js

@@ -61,6 +61,10 @@ module.exports = function (context, options) {
     name: 'docusaurus-theme-classic',
 
     getThemePath() {
+      return path.join(__dirname, '..', 'lib', 'theme');
+    },
+
+    getTypeScriptThemePath() {
       return path.resolve(__dirname, './theme');
     },
 

packages/docusaurus-theme-classic/src/theme/AnnouncementBar/index.tsx

@@ -11,9 +11,9 @@ import useUserPreferencesContext from '@theme/hooks/useUserPreferencesContext';
 
 import styles from './styles.module.css';
 
-function AnnouncementBar() {
+function AnnouncementBar(): JSX.Element | null {
   const {
-    siteConfig: {themeConfig: {announcementBar = {}}} = {},
+    siteConfig: {themeConfig: {announcementBar = {}} = {}} = {},
   } = useDocusaurusContext();
   const {content, backgroundColor, textColor} = announcementBar;
   const {

packages/docusaurus-theme-classic/src/theme/BlogListPage/index.tsx

@@ -12,7 +12,12 @@ import Layout from '@theme/Layout';
 import BlogPostItem from '@theme/BlogPostItem';
 import BlogListPaginator from '@theme/BlogListPaginator';
 
-function BlogListPage(props) {
+type Props = {
+  metadata: {permalink: string; title: string};
+  items: {content}[];
+};
+
+function BlogListPage(props: Props): JSX.Element {
   const {metadata, items} = props;
   const {
     siteConfig: {title: siteTitle},

packages/docusaurus-theme-classic/src/theme/BlogListPaginator/index.tsx

@@ -8,7 +8,7 @@
 import React from 'react';
 import Link from '@docusaurus/Link';
 
-function BlogListPaginator(props) {
+function BlogListPaginator(props): JSX.Element {
   const {metadata} = props;
   const {previousPage, nextPage} = metadata;
 

packages/docusaurus-theme-classic/src/theme/BlogPostItem/index.tsx

@@ -31,7 +31,7 @@ const MONTHS = [
   'December',
 ];
 
-function BlogPostItem(props) {
+function BlogPostItem(props): JSX.Element {
   const {
     children,
     frontMatter,

packages/docusaurus-theme-classic/src/theme/BlogPostPage/index.tsx

@@ -11,7 +11,7 @@ import Layout from '@theme/Layout';
 import BlogPostItem from '@theme/BlogPostItem';
 import BlogPostPaginator from '@theme/BlogPostPaginator';
 
-function BlogPostPage(props) {
+function BlogPostPage(props): JSX.Element {
   const {content: BlogPostContents} = props;
   const {frontMatter, metadata} = BlogPostContents;
   const {title, description, nextItem, prevItem, editUrl} = metadata;

packages/docusaurus-theme-classic/src/theme/BlogPostPaginator/index.tsx

@@ -8,7 +8,7 @@
 import React from 'react';
 import Link from '@docusaurus/Link';
 
-function BlogPostPaginator(props) {
+function BlogPostPaginator(props): JSX.Element {
   const {nextItem, prevItem} = props;
 
   return (

packages/docusaurus-theme-classic/src/theme/BlogTagsListPage/index.tsx

@@ -10,15 +10,17 @@ import React from 'react';
 import Layout from '@theme/Layout';
 import Link from '@docusaurus/Link';
 
-function getCategoryOfTag(tag) {
+function getCategoryOfTag(tag: string) {
   // tag's category should be customizable
   return tag[0].toUpperCase();
 }
 
-function BlogTagsListPage(props) {
+type Tag = {permalink: string; name: string; count: number};
+
+function BlogTagsListPage(props: {tags: Record<string, Tag>}): JSX.Element {
   const {tags} = props;
 
-  const tagCategories = {};
+  const tagCategories: {[category: string]: string[]} = {};
   Object.keys(tags).forEach((tag) => {
     const category = getCategoryOfTag(tag);
     tagCategories[category] = tagCategories[category] || [];

packages/docusaurus-theme-classic/src/theme/BlogTagsPostsPage/index.tsx

@@ -11,11 +11,11 @@ import Layout from '@theme/Layout';
 import BlogPostItem from '@theme/BlogPostItem';
 import Link from '@docusaurus/Link';
 
-function pluralize(count, word) {
+function pluralize(count: number, word: string) {
   return count > 1 ? `${word}s` : word;
 }
 
-function BlogTagsPostPage(props) {
+function BlogTagsPostPage(props): JSX.Element {
   const {metadata, items} = props;
   const {allTagsPath, name: tagName, count} = metadata;
 

packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx

@@ -87,7 +87,15 @@ const highlightDirectiveRegex = (lang) => {
 };
 const codeBlockTitleRegex = /title=".*"/;
 
-export default ({children, className: languageClassName, metastring}) => {
+export default ({
+  children,
+  className: languageClassName,
+  metastring,
+}: {
+  children: string;
+  className: string;
+  metastring: string;
+}): JSX.Element => {
   const {
     siteConfig: {
       themeConfig: {prism = {}},
@@ -108,21 +116,25 @@ export default ({children, className: languageClassName, metastring}) => {
   }, []);
 
   const button = useRef(null);
-  let highlightLines = [];
+  let highlightLines: number[] = [];
   let codeBlockTitle = '';
 
   const prismTheme = usePrismTheme();
 
   if (metastring && highlightLinesRangeRegex.test(metastring)) {
-    const highlightLinesRange = metastring.match(highlightLinesRangeRegex)[1];
+    // Tested above
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+    const highlightLinesRange = metastring.match(highlightLinesRangeRegex)![1];
     highlightLines = rangeParser
       .parse(highlightLinesRange)
       .filter((n) => n > 0);
   }
 
   if (metastring && codeBlockTitleRegex.test(metastring)) {
+    // Tested above
+    // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     codeBlockTitle = metastring
-      .match(codeBlockTitleRegex)[0]
+      .match(codeBlockTitleRegex)![0]
       .split('title=')[1]
       .replace(/"+/g, '');
   }
@@ -151,7 +163,10 @@ export default ({children, className: languageClassName, metastring}) => {
       if (match !== null) {
         const directive = match
           .slice(1)
-          .reduce((final, item) => final || item, undefined);
+          .reduce(
+            (final: string | undefined, item) => final || item,
+            undefined,
+          );
         switch (directive) {
           case 'highlight-next-line':
             range += `${lineNumber},`;
@@ -188,9 +203,10 @@ export default ({children, className: languageClassName, metastring}) => {
   return (
     <Highlight
       {...defaultProps}
-      key={mounted}
+      key={String(mounted)}
       theme={prismTheme}
       code={code}
+      // @ts-expect-error: prism-react-renderer doesn't export Language type
       language={language}>
       {({className, style, tokens, getLineProps, getTokenProps}) => (
         <>
@@ -211,7 +227,7 @@ export default ({children, className: languageClassName, metastring}) => {
               {showCopied ? 'Copied' : 'Copy'}
             </button>
             <div
-              tabIndex="0"
+              tabIndex={0}
               className={clsx(className, styles.codeBlock, {
                 [styles.codeBlockWithTitle]: codeBlockTitle,
               })}>

packages/docusaurus-theme-classic/src/theme/DocItem/index.tsx

@@ -33,7 +33,7 @@ function DocTOC({headings}) {
 }
 
 /* eslint-disable jsx-a11y/control-has-associated-label */
-function Headings({headings, isChild}) {
+function Headings({headings, isChild}: {headings; isChild?: boolean}) {
   if (!headings.length) {
     return null;
   }
@@ -58,7 +58,7 @@ function Headings({headings, isChild}) {
   );
 }
 
-function DocItem(props) {
+function DocItem(props): JSX.Element {
   const {siteConfig = {}} = useDocusaurusContext();
   const {url: siteUrl, title: siteTitle} = siteConfig;
   const {content: DocContent} = props;

packages/docusaurus-theme-classic/src/theme/DocPage/index.tsx

@@ -18,7 +18,7 @@ import {matchPath} from '@docusaurus/router';
 
 import styles from './styles.module.css';
 
-function DocPage(props) {
+function DocPage(props): JSX.Element {
   const {route: baseRoute, docsMetadata, location} = props;
   // case-sensitive route such as it is defined in the sidebar
   const currentRoute =

packages/docusaurus-theme-classic/src/theme/DocPaginator/index.tsx

@@ -8,7 +8,13 @@
 import React from 'react';
 import Link from '@docusaurus/Link';
 
-function DocPaginator(props) {
+type PageInfo = {permalink: string; title: string};
+
+type Props = {
+  metadata: {previous: PageInfo; next: PageInfo};
+};
+
+function DocPaginator(props: Props): JSX.Element {
   const {metadata} = props;
 
   return (

packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx

@@ -163,11 +163,11 @@ function DocSidebarItem(props) {
   }
 }
 
-function DocSidebar(props) {
+function DocSidebar(props): JSX.Element | null {
   const [showResponsiveSidebar, setShowResponsiveSidebar] = useState(false);
   const {
     siteConfig: {
-      themeConfig: {navbar: {title, hideOnScroll = false} = {}},
+      themeConfig: {navbar: {title = '', hideOnScroll = false} = {}} = {},
     } = {},
     isClient,
   } = useDocusaurusContext();

packages/docusaurus-theme-classic/src/theme/Footer/index.tsx

@@ -39,7 +39,7 @@ const FooterLogo = ({url, alt}) => (
   <img className="footer__logo" alt={alt} src={url} />
 );
 
-function Footer() {
+function Footer(): JSX.Element | null {
   const context = useDocusaurusContext();
   const {siteConfig = {}} = context;
   const {themeConfig = {}} = siteConfig;

packages/docusaurus-theme-classic/src/theme/Heading/index.tsx

@@ -7,14 +7,14 @@
 
 /* eslint-disable jsx-a11y/anchor-has-content, jsx-a11y/anchor-is-valid */
 
-import React from 'react';
+import React, {ComponentType} from 'react';
 import clsx from 'clsx';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 
 import './styles.css';
 import styles from './styles.module.css';
 
-const Heading = (Tag) =>
+const Heading = (Tag: ComponentType): ((props) => JSX.Element) =>
   function TargetComponent({id, ...props}) {
     const {
       siteConfig: {
@@ -30,7 +30,7 @@ const Heading = (Tag) =>
       <Tag {...props}>
         <a
           aria-hidden="true"
-          tabIndex="-1"
+          tabIndex={-1}
           className={clsx('anchor', {
             [styles.enhancedAnchor]: !hideOnScroll,
           })}
@@ -39,7 +39,7 @@ const Heading = (Tag) =>
         {props.children}
         <a
           aria-hidden="true"
-          tabIndex="-1"
+          tabIndex={-1}
           className="hash-link"
           href={`#${id}`}
           title="Direct link to heading">

packages/docusaurus-theme-classic/src/theme/Layout/index.tsx

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React, {ReactNode} from 'react';
 import Head from '@docusaurus/Head';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 import useBaseUrl from '@docusaurus/useBaseUrl';
@@ -18,7 +18,18 @@ import Footer from '@theme/Footer';
 
 import './styles.css';
 
-function Layout(props) {
+type Props = {
+  children: ReactNode;
+  title?: string;
+  noFooter?: boolean;
+  description?: string;
+  image?: string;
+  keywords?: string[];
+  permalink?: string;
+  version?: string;
+};
+
+function Layout(props: Props): JSX.Element {
   const {siteConfig = {}} = useDocusaurusContext();
   const {
     favicon,

packages/docusaurus-theme-classic/src/theme/MDXComponents/index.tsx

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React, {ComponentProps} from 'react';
 import Link from '@docusaurus/Link';
 import CodeBlock from '@theme/CodeBlock';
 import Heading from '@theme/Heading';
@@ -13,7 +13,7 @@ import Heading from '@theme/Heading';
 import styles from './styles.module.css';
 
 export default {
-  code: (props) => {
+  code: (props: ComponentProps<typeof CodeBlock>): JSX.Element => {
     const {children} = props;
     if (typeof children === 'string') {
       if (!children.includes('\n')) {
@@ -23,14 +23,16 @@ export default {
     }
     return children;
   },
-  a: (props) => {
-    if (/\.[^./]+$/.test(props.href)) {
+  a: (props: ComponentProps<'a'>): JSX.Element => {
+    if (/\.[^./]+$/.test(props.href || '')) {
       // eslint-disable-next-line jsx-a11y/anchor-has-content
       return <a {...props} />;
     }
     return <Link {...props} />;
   },
-  pre: (props) => <div className={styles.mdxCodeBlock} {...props} />,
+  pre: (props: ComponentProps<'div'>): JSX.Element => (
+    <div className={styles.mdxCodeBlock} {...props} />
+  ),
   h1: Heading('h1'),
   h2: Heading('h2'),
   h3: Heading('h3'),

packages/docusaurus-theme-classic/src/theme/Navbar/index.tsx

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React, {useCallback, useState, useEffect} from 'react';
+import React, {useCallback, useState, useEffect, ComponentProps} from 'react';
 import clsx from 'clsx';
 import Link from '@docusaurus/Link';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
@@ -33,7 +33,15 @@ function NavLink({
   activeClassName = 'navbar__link--active',
   prependBaseUrlToHref,
   ...props
-}) {
+}: {
+  activeBasePath?: string;
+  activeBaseRegex?: string;
+  to?: string;
+  href?: string;
+  label?: string;
+  activeClassName?: string;
+  prependBaseUrlToHref?: string;
+} & ComponentProps<'a'>) {
   const toUrl = useBaseUrl(to);
   const activeBaseUrl = useBaseUrl(activeBasePath);
   const normalizedHref = useBaseUrl(href, {forcePrependBaseUrl: true});
@@ -96,7 +104,8 @@ function NavItem({
         onClick={(e) => e.preventDefault()}
         onKeyDown={(e) => {
           if (e.key === 'Enter') {
-            e.target.parentNode.classList.toggle('dropdown--show');
+            ((e.target as HTMLElement)
+              .parentNode as HTMLElement).classList.toggle('dropdown--show');
           }
         }}>
         {props.label}
@@ -171,11 +180,11 @@ function splitLinks(links) {
   };
 }
 
-function Navbar() {
+function Navbar(): JSX.Element {
   const {
     siteConfig: {
       themeConfig: {
-        navbar: {title, links = [], hideOnScroll = false} = {},
+        navbar: {title = '', links = [], hideOnScroll = false} = {},
         disableDarkMode = false,
       },
     },

packages/docusaurus-theme-classic/src/theme/NotFound.tsx

@@ -8,7 +8,7 @@
 import React from 'react';
 import Layout from '@theme/Layout';
 
-function NotFound() {
+function NotFound(): JSX.Element {
   return (
     <Layout title="Page Not Found">
       <div className="container margin-vert--xl">

packages/docusaurus-theme-classic/src/theme/TabItem/index.tsx

@@ -5,9 +5,9 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React, {ReactNode} from 'react';
 
-function TabItem(props) {
+function TabItem(props: {readonly children: ReactNode}): JSX.Element {
   return <div>{props.children}</div>;
 }
 

packages/docusaurus-theme-classic/src/theme/Tabs/index.tsx

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React, {useState, Children} from 'react';
+import React, {useState, Children, ReactElement} from 'react';
 import useUserPreferencesContext from '@theme/hooks/useUserPreferencesContext';
 
 import clsx from 'clsx';
@@ -17,7 +17,15 @@ const keys = {
   right: 39,
 };
 
-function Tabs(props) {
+type Props = {
+  block?: boolean;
+  children: ReactElement<{value: string}>[];
+  defaultValue?: string;
+  values: {value: string; label: string}[];
+  groupId?: string;
+};
+
+function Tabs(props: Props): JSX.Element {
   const {block, children, defaultValue, values, groupId} = props;
   const {tabGroupChoices, setTabGroupChoices} = useUserPreferencesContext();
   const [selectedValue, setSelectedValue] = useState(defaultValue);
@@ -40,7 +48,7 @@ function Tabs(props) {
     }
   };
 
-  const tabRefs = [];
+  const tabRefs: (HTMLLIElement | null)[] = [];
 
   const focusNextTab = (tabs, target) => {
     const next = tabs.indexOf(target) + 1;
@@ -86,7 +94,7 @@ function Tabs(props) {
         {values.map(({value, label}) => (
           <li
             role="tab"
-            tabIndex="0"
+            tabIndex={0}
             aria-selected={selectedValue === value}
             className={clsx('tabs__item', styles.tabItem, {
               'tabs__item--active': selectedValue === value,
@@ -103,7 +111,9 @@ function Tabs(props) {
       <div role="tabpanel" className="margin-vert--md">
         {
           Children.toArray(children).filter(
-            (child) => child.props.value === selectedValue,
+            (child) =>
+              (child as ReactElement<{value: string}>).props.value ===
+              selectedValue,
           )[0]
         }
       </div>

packages/docusaurus-theme-classic/src/theme/ThemeContext.ts

@@ -7,6 +7,6 @@
 
 import React from 'react';
 
-const ThemeContext = React.createContext();
+const ThemeContext = React.createContext(undefined);
 
 export default ThemeContext;

packages/docusaurus-theme-classic/src/theme/ThemeProvider/index.tsx

@@ -5,12 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React, {ReactNode} from 'react';
 
 import useTheme from '@theme/hooks/useTheme';
 import ThemeContext from '@theme/ThemeContext';
 
-function ThemeProvider(props) {
+function ThemeProvider(props: {readonly children: ReactNode}): JSX.Element {
   const {isDarkTheme, setLightTheme, setDarkTheme} = useTheme();
 
   return (

packages/docusaurus-theme-classic/src/theme/Toggle/index.tsx

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React, {ComponentProps} from 'react';
 import Toggle from 'react-toggle';
 
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
@@ -16,7 +16,7 @@ import styles from './styles.module.css';
 const Moon = () => <span className={clsx(styles.toggle, styles.moon)} />;
 const Sun = () => <span className={clsx(styles.toggle, styles.sun)} />;
 
-export default function (props) {
+export default function (props: ComponentProps<typeof Toggle>): JSX.Element {
   const {isClient} = useDocusaurusContext();
   return (
     <Toggle

packages/docusaurus-theme-classic/src/theme/UserPreferencesContext.ts

@@ -7,6 +7,6 @@
 
 import {createContext} from 'react';
 
-const UserPreferencesContext = createContext();
+const UserPreferencesContext = createContext(undefined);
 
 export default UserPreferencesContext;

packages/docusaurus-theme-classic/src/theme/UserPreferencesProvider/index.tsx

@@ -5,13 +5,13 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import React from 'react';
+import React, {ReactNode} from 'react';
 
 import useTabGroupChoice from '@theme/hooks/useTabGroupChoice';
 import useAnnouncementBar from '@theme/hooks/useAnnouncementBar';
 import UserPreferencesContext from '@theme/UserPreferencesContext';
 
-function UserPreferencesProvider(props) {
+function UserPreferencesProvider(props: {children: ReactNode}): JSX.Element {
   const {tabGroupChoices, setTabGroupChoices} = useTabGroupChoice();
   const {isAnnouncementBarClosed, closeAnnouncementBar} = useAnnouncementBar();
 

packages/docusaurus-theme-classic/src/theme/hooks/useAnnouncementBar.ts

@@ -11,13 +11,18 @@ import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 const STORAGE_DISMISS_KEY = 'docusaurus.announcement.dismiss';
 const STORAGE_ID_KEY = 'docusaurus.announcement.id';
 
-const useAnnouncementBar = () => {
+const useAnnouncementBar = (): {
+  isAnnouncementBarClosed: boolean;
+  closeAnnouncementBar: () => void;
+} => {
   const {
-    siteConfig: {themeConfig: {announcementBar: {id} = {}}} = {},
+    siteConfig: {
+      themeConfig: {announcementBar: {id = 'annoucement-bar'} = {}} = {},
+    } = {},
   } = useDocusaurusContext();
   const [isClosed, setClosed] = useState(true);
   const handleClose = () => {
-    localStorage.setItem(STORAGE_DISMISS_KEY, true);
+    localStorage.setItem(STORAGE_DISMISS_KEY, 'true');
     setClosed(true);
   };
 
@@ -32,7 +37,7 @@ const useAnnouncementBar = () => {
     localStorage.setItem(STORAGE_ID_KEY, id);
 
     if (isNewAnnouncement) {
-      localStorage.setItem(STORAGE_DISMISS_KEY, false);
+      localStorage.setItem(STORAGE_DISMISS_KEY, 'false');
     }
 
     if (

packages/docusaurus-theme-classic/src/theme/hooks/useHideableNavbar.ts

@@ -10,7 +10,7 @@ import {useLocation} from '@docusaurus/router';
 import useLocationHash from '@theme/hooks/useLocationHash';
 import useScrollPosition from '@theme/hooks/useScrollPosition';
 
-const useHideableNavbar = (hideOnScroll) => {
+const useHideableNavbar = (hideOnScroll: boolean) => {
   const [isNavbarVisible, setIsNavbarVisible] = useState(true);
   const [isFocusedAnchor, setIsFocusedAnchor] = useState(false);
   const [lastScrollTop, setLastScrollTop] = useState(0);

packages/docusaurus-theme-classic/src/theme/hooks/useLocationHash.ts

@@ -5,9 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {useState, useEffect} from 'react';
+import {useState, useEffect, Dispatch, SetStateAction} from 'react';
 
-function useLocationHash(initialHash) {
+function useLocationHash(
+  initialHash: string,
+): [string, Dispatch<SetStateAction<string>>] {
   const [hash, setHash] = useState(initialHash);
 
   useEffect(() => {

packages/docusaurus-theme-classic/src/theme/hooks/useLockBodyScroll.ts

@@ -7,7 +7,7 @@
 
 import {useEffect} from 'react';
 
-function useLockBodyScroll(lock = true) {
+function useLockBodyScroll(lock: boolean = true): void {
   useEffect(() => {
     document.body.style.overflow = lock ? 'hidden' : 'visible';
 

packages/docusaurus-theme-classic/src/theme/hooks/useLogo.ts

@@ -10,13 +10,20 @@ import useThemeContext from '@theme/hooks/useThemeContext';
 import useBaseUrl from '@docusaurus/useBaseUrl';
 import isInternalUrl from '@docusaurus/isInternalUrl';
 
-const useLogo = () => {
+type LogoLinkProps = {target?: string; rel?: string};
+
+const useLogo = (): {
+  logoLink: string;
+  logoLinkProps: LogoLinkProps;
+  logoImageUrl: string;
+  logoAlt: string;
+} => {
   const {
-    siteConfig: {themeConfig: {navbar: {logo = {}} = {}}} = {},
+    siteConfig: {themeConfig: {navbar: {logo = {}} = {}} = {}} = {},
   } = useDocusaurusContext();
   const {isDarkTheme} = useThemeContext();
   const logoLink = useBaseUrl(logo.href || '/');
-  let logoLinkProps = {};
+  let logoLinkProps: LogoLinkProps = {};
 
   if (logo.target) {
     logoLinkProps = {target: logo.target};

packages/docusaurus-theme-classic/src/theme/hooks/usePrismTheme.ts

@@ -9,7 +9,7 @@ import defaultTheme from 'prism-react-renderer/themes/palenight';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 import useThemeContext from '@theme/hooks/useThemeContext';
 
-const usePrismTheme = () => {
+const usePrismTheme = (): typeof defaultTheme => {
   const {
     siteConfig: {
       themeConfig: {prism = {}},

packages/docusaurus-theme-classic/src/theme/hooks/useScrollPosition.ts

@@ -8,12 +8,17 @@
 import {useState, useEffect} from 'react';
 import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
 
-const getScrollPosition = () => ({
+type ScrollPosition = {scrollX: number; scrollY: number};
+
+const getScrollPosition = (): ScrollPosition => ({
   scrollX: ExecutionEnvironment.canUseDOM ? window.pageXOffset : 0,
   scrollY: ExecutionEnvironment.canUseDOM ? window.pageYOffset : 0,
 });
 
-const useScrollPosition = (effect, deps = []) => {
+const useScrollPosition = (
+  effect: (position: ScrollPosition) => void,
+  deps = [],
+): ScrollPosition => {
   const [scrollPosition, setScrollPosition] = useState(getScrollPosition());
 
   const handleScroll = () => {
@@ -31,6 +36,7 @@ const useScrollPosition = (effect, deps = []) => {
 
     return () =>
       window.removeEventListener('scroll', handleScroll, {
+        // @ts-expect-error: See https://github.com/microsoft/TypeScript/issues/32912
         passive: true,
       });
   }, deps);

packages/docusaurus-theme-classic/src/theme/hooks/useTOCHighlight.ts

@@ -7,17 +7,23 @@
 
 import {useEffect, useState} from 'react';
 
-function useTOCHighlight(linkClassName, linkActiveClassName, topOffset) {
-  const [lastActiveLink, setLastActiveLink] = useState(undefined);
+function useTOCHighlight(
+  linkClassName: string,
+  linkActiveClassName: string,
+  topOffset: number,
+): void {
+  const [lastActiveLink, setLastActiveLink] = useState<HTMLAnchorElement>(
+    undefined!,
+  );
 
   useEffect(() => {
-    let headersAnchors = [];
-    let links = [];
+    let headersAnchors: HTMLCollectionOf<Element>;
+    let links: HTMLCollectionOf<HTMLAnchorElement>;
 
     function setActiveLink() {
       function getActiveHeaderAnchor() {
         let index = 0;
-        let activeHeaderAnchor = null;
+        let activeHeaderAnchor: Element | null = null;
 
         headersAnchors = document.getElementsByClassName('anchor');
         while (index < headersAnchors.length && !activeHeaderAnchor) {
@@ -40,6 +46,7 @@ function useTOCHighlight(linkClassName, linkActiveClassName, topOffset) {
         let index = 0;
         let itemHighlighted = false;
 
+        // @ts-expect-error: Must be <a> tags.
         links = document.getElementsByClassName(linkClassName);
         while (index < links.length && !itemHighlighted) {
           const link = links[index];

packages/docusaurus-theme-classic/src/theme/hooks/useTabGroupChoice.ts

@@ -9,8 +9,13 @@ import {useState, useCallback, useEffect} from 'react';
 
 const TAB_CHOICE_PREFIX = 'docusaurus.tab.';
 
-const useTabGroupChoice = () => {
-  const [tabGroupChoices, setChoices] = useState({});
+const useTabGroupChoice = (): {
+  tabGroupChoices: {readonly [groupId: string]: string};
+  setTabGroupChoices: (groupId: string, newChoice: string) => void;
+} => {
+  const [tabGroupChoices, setChoices] = useState<{
+    readonly [groupId: string]: string;
+  }>({});
   const setChoiceSyncWithLocalStorage = useCallback((groupId, newChoice) => {
     try {
       localStorage.setItem(`${TAB_CHOICE_PREFIX}${groupId}`, newChoice);
@@ -23,7 +28,7 @@ const useTabGroupChoice = () => {
     try {
       const localStorageChoices = {};
       for (let i = 0; i < localStorage.length; i += 1) {
-        const storageKey = localStorage.key(i);
+        const storageKey = localStorage.key(i) as string;
         if (storageKey.startsWith(TAB_CHOICE_PREFIX)) {
           const groupId = storageKey.substring(TAB_CHOICE_PREFIX.length);
           localStorageChoices[groupId] = localStorage.getItem(storageKey);
@@ -37,7 +42,7 @@ const useTabGroupChoice = () => {
 
   return {
     tabGroupChoices,
-    setTabGroupChoices: (groupId, newChoice) => {
+    setTabGroupChoices: (groupId: string, newChoice: string) => {
       setChoices((oldChoices) => ({...oldChoices, [groupId]: newChoice}));
       setChoiceSyncWithLocalStorage(groupId, newChoice);
     },

packages/docusaurus-theme-classic/src/theme/hooks/useTheme.ts

@@ -14,9 +14,13 @@ const themes = {
   dark: 'dark',
 };
 
-const useTheme = () => {
+const useTheme = (): {
+  isDarkTheme: boolean;
+  setLightTheme: () => void;
+  setDarkTheme: () => void;
+} => {
   const {
-    siteConfig: {themeConfig: {disableDarkMode}} = {},
+    siteConfig: {themeConfig: {disableDarkMode = false} = {}} = {},
   } = useDocusaurusContext();
   const [theme, setTheme] = useState(
     typeof document !== 'undefined'
@@ -43,6 +47,7 @@ const useTheme = () => {
   }, []);
 
   useEffect(() => {
+    // @ts-expect-error: safe to set null as attribute
     document.documentElement.setAttribute('data-theme', theme);
   }, [theme]);
 

packages/docusaurus-theme-classic/src/theme/hooks/useThemeContext.ts

@@ -9,8 +9,14 @@ import {useContext} from 'react';
 
 import ThemeContext from '@theme/ThemeContext';
 
-function useThemeContext() {
-  const context = useContext(ThemeContext);
+type ThemeContextProps = {
+  isDarkTheme: boolean;
+  setLightTheme: () => void;
+  setDarkTheme: () => void;
+};
+
+function useThemeContext(): ThemeContextProps {
+  const context = useContext<ThemeContextProps>(ThemeContext);
   if (context == null) {
     throw new Error(
       '`useThemeContext` is used outside of `Layout` Component. See https://v2.docusaurus.io/docs/theme-classic#usethemecontext.',

packages/docusaurus-theme-classic/src/theme/hooks/useUserPreferencesContext.ts

@@ -9,8 +9,17 @@ import {useContext} from 'react';
 
 import UserPreferencesContext from '@theme/UserPreferencesContext';
 
-function useUserPreferencesContext() {
-  const context = useContext(UserPreferencesContext);
+type UserPreferencesContextProps = {
+  tabGroupChoices: {readonly [groupId: string]: string};
+  setTabGroupChoices: (groupId: string, newChoice: string) => void;
+  isAnnouncementBarClosed: boolean;
+  closeAnnouncementBar: () => void;
+};
+
+function useUserPreferencesContext(): UserPreferencesContextProps {
+  const context = useContext<UserPreferencesContextProps>(
+    UserPreferencesContext,
+  );
   if (context == null) {
     throw new Error(
       '`useUserPreferencesContext` is used outside of `Layout` Component.',

packages/docusaurus-theme-classic/src/theme/hooks/useWindowSize.ts

@@ -12,9 +12,11 @@ const desktopThresholdWidth = 996;
 const windowSizes = {
   desktop: 'desktop',
   mobile: 'mobile',
-};
+} as const;
 
-function useWindowSize() {
+type WindowSize = keyof typeof windowSizes;
+
+function useWindowSize(): WindowSize | undefined {
   const isClient = typeof window !== 'undefined';
 
   function getSize() {
@@ -30,7 +32,7 @@ function useWindowSize() {
 
   useEffect(() => {
     if (!isClient) {
-      return false;
+      return undefined;
     }
 
     function handleResize() {

packages/docusaurus-theme-classic/src/theme/prism-include-languages.ts

@@ -7,16 +7,17 @@
 
 import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
 import siteConfig from '@generated/docusaurus.config';
+import type * as PrismNamespace from 'prismjs';
 
-const prismIncludeLanguages = (Prism) => {
+const prismIncludeLanguages = (PrismObject: typeof PrismNamespace): void => {
   if (ExecutionEnvironment.canUseDOM) {
     const {
       themeConfig: {prism: {additionalLanguages = []} = {}},
     } = siteConfig;
 
-    window.Prism = Prism;
+    window.Prism = PrismObject;
 
-    additionalLanguages.forEach((lang) => {
+    additionalLanguages.forEach((lang: string) => {
       require(`prismjs/components/prism-${lang}`); // eslint-disable-line
     });
 

packages/docusaurus-theme-classic/src/types.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// eslint-disable-next-line spaced-comment
+/// <reference types="@docusaurus/module-type-aliases" />

packages/docusaurus-theme-classic/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "lib": ["DOM"],
+    "module": "esnext",
+    "noEmit": true,
+    "noImplicitAny": false,
+    "jsx": "react",
+    "baseUrl": "src"
+  },
+  "include": ["src/"]
+}

packages/docusaurus-types/src/index.d.ts

@@ -120,6 +120,7 @@ export interface Plugin<T, U = unknown> {
     utils: ConfigureWebpackUtils,
   ): Configuration;
   getThemePath?(): string;
+  getTypeScriptThemePath?(): string;
   getPathsToWatch?(): string[];
   getClientModules?(): string[];
   extendCli?(cli: Command): void;

packages/docusaurus-utils/src/index.ts

@@ -60,7 +60,7 @@ export function objectWithKeySorted(obj: {[index: string]: any}) {
 }
 
 const indexRE = /(^|.*\/)index\.(md|js|jsx|ts|tsx)$/i;
-const extRE = /\.(md|js|tsx)$/;
+const extRE = /\.(md|js|ts|tsx)$/;
 
 /**
  * Convert filepath to url path.

packages/docusaurus/bin/docusaurus.js

@@ -60,8 +60,17 @@ cli
 cli
   .command('swizzle <themeName> [componentName] [siteDir]')
   .description('Copy the theme files into website folder for customization.')
-  .action((themeName, componentName, siteDir = '.') => {
-    wrapCommand(swizzle)(path.resolve(siteDir), themeName, componentName);
+  .option(
+    '--typescript',
+    'Copy TypeScript theme files when possible (default: false)',
+  )
+  .action((themeName, componentName, siteDir = '.', {typescript}) => {
+    wrapCommand(swizzle)(
+      path.resolve(siteDir),
+      themeName,
+      componentName,
+      typescript,
+    );
   });
 
 cli

packages/docusaurus/src/commands/swizzle.ts

@@ -18,13 +18,16 @@ export default async function swizzle(
   siteDir: string,
   themeName: string,
   componentName?: string,
+  typescript?: boolean,
 ): Promise<void> {
   const plugin = importFresh(themeName) as (
     context: LoadContext,
   ) => Plugin<unknown>;
   const context = loadContext(siteDir);
   const pluginInstance = plugin(context);
-  let fromPath = pluginInstance.getThemePath?.();
+  let fromPath = typescript
+    ? pluginInstance.getTypeScriptThemePath?.()
+    : pluginInstance.getThemePath?.();
 
   if (fromPath) {
     let toPath = path.resolve(siteDir, THEME_PATH);
@@ -32,10 +35,16 @@ export default async function swizzle(
       fromPath = path.join(fromPath, componentName);
       toPath = path.join(toPath, componentName);
 
-      // Handle single JavaScript file only.
-      // E.g: if <fromPath> does not exist, we try to swizzle <fromPath>.js instead
-      if (!fs.existsSync(fromPath) && fs.existsSync(`${fromPath}.js`)) {
-        [fromPath, toPath] = [`${fromPath}.js`, `${toPath}.js`];
+      // Handle single TypeScript/JavaScript file only.
+      // E.g: if <fromPath> does not exist, we try to swizzle <fromPath>.(ts|tsx|js) instead
+      if (!fs.existsSync(fromPath)) {
+        if (fs.existsSync(`${fromPath}.ts`)) {
+          [fromPath, toPath] = [`${fromPath}.ts`, `${toPath}.ts`];
+        } else if (fs.existsSync(`${fromPath}.tsx`)) {
+          [fromPath, toPath] = [`${fromPath}.tsx`, `${toPath}.tsx`];
+        } else if (fs.existsSync(`${fromPath}.js`)) {
+          [fromPath, toPath] = [`${fromPath}.js`, `${toPath}.js`];
+        }
       }
     }
     await fs.copy(fromPath, toPath);
@@ -48,5 +57,13 @@ export default async function swizzle(
     console.log(
       `\n${chalk.green('Success!')} Copied ${fromMsg} to ${toMsg}.\n`,
     );
+  } else if (typescript) {
+    console.warn(
+      chalk.yellow(
+        `${themeName} does not provide TypeScript theme code via getTypeScriptThemePath().`,
+      ),
+    );
+  } else {
+    console.warn(chalk.yellow(`${themeName} does not provide any theme code.`));
   }
 }

tsconfig.json

@@ -2,7 +2,7 @@
   "compilerOptions": {
     "target": "es2017",
     "module": "commonjs",
-    "lib": ["es2017","es2019.array"],
+    "lib": ["es2017","es2019.array", "DOM"],
     "declaration": true,
     "declarationMap": true,
 

website/src/theme/NotFound.tsx

@@ -9,7 +9,7 @@ import React from 'react';
 import Layout from '@theme/Layout';
 import Feedback from '../pages/feedback';
 
-function NotFound({location}) {
+function NotFound({location}: {location: {pathname: string}}): JSX.Element {
   if (/^\/feedback/.test(location.pathname)) {
     return <Feedback />;
   }

website/src/types.d.ts

@@ -0,0 +1,9 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// eslint-disable-next-line spaced-comment
+/// <reference types="@docusaurus/module-type-aliases" />

website/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  // This file is not used in compilation. It is here just for a nice editor experience.
+  "extends": "../tsconfig.json",
+  "compilerOptions": {
+    "lib": ["DOM"],
+    "module": "esnext",
+    "noEmit": true,
+    "noImplicitAny": false,
+    "jsx": "react",
+    "baseUrl": "src"
+  },
+  "include": ["src/"]
+}

yarn.lock

@@ -2,6 +2,22 @@
 # yarn lockfile v1
 
 
+"@babel/cli@^7.9.0":
+  version "7.10.3"
+  resolved "https://registry.yarnpkg.com/@babel/cli/-/cli-7.10.3.tgz#4ea83bd997d2a41c78d07263ada3ec466fb3764b"
+  integrity sha512-lWB3yH5/fWY8pi2Kj5/fA+17guJ9feSBw5DNjTju3/nRi9sXnl1JPh7aKQOSvdNbiDbkzzoGYtsr46M8dGmXDQ==
+  dependencies:
+    commander "^4.0.1"
+    convert-source-map "^1.1.0"
+    fs-readdir-recursive "^1.1.0"
+    glob "^7.0.0"
+    lodash "^4.17.13"
+    make-dir "^2.1.0"
+    slash "^2.0.0"
+    source-map "^0.5.0"
+  optionalDependencies:
+    chokidar "^2.1.8"
+
 "@babel/code-frame@7.5.5":
   version "7.5.5"
   resolved "https://registry.yarnpkg.com/@babel/code-frame/-/code-frame-7.5.5.tgz#bc0782f6d69f7b7d49531219699b988f669a8f9d"
@@ -3051,6 +3067,11 @@
   resolved "https://registry.yarnpkg.com/@types/prettier/-/prettier-1.19.1.tgz#33509849f8e679e4add158959fdb086440e9553f"
   integrity sha512-5qOlnZscTn4xxM5MeGXAMOsIOIKIbh9e85zJWfBRVPlRMEVawzoPhINYbRGkBZCI8LxvBe7tJCdWiarA99OZfQ==
 
+"@types/prismjs@^1.16.1":
+  version "1.16.1"
+  resolved "https://registry.yarnpkg.com/@types/prismjs/-/prismjs-1.16.1.tgz#50b82947207847db6abcbcd14caa89e3b897c259"
+  integrity sha512-RNgcK3FEc1GpeOkamGDq42EYkb6yZW5OWQwTS56NJIB8WL0QGISQglA7En7NUx9RGP8AC52DOe+squqbAckXlA==
+
 "@types/prop-types@*":
   version "15.7.3"
   resolved "https://registry.yarnpkg.com/@types/prop-types/-/prop-types-15.7.3.tgz#2ab0d5da2e5815f94b0b9d4b95d1e5f243ab2ca7"
@@ -5807,7 +5828,7 @@ conventional-recommended-bump@^5.0.0:
     meow "^4.0.0"
     q "^1.5.1"
 
-convert-source-map@^1.4.0, convert-source-map@^1.6.0, convert-source-map@^1.7.0:
+convert-source-map@^1.1.0, convert-source-map@^1.4.0, convert-source-map@^1.6.0, convert-source-map@^1.7.0:
   version "1.7.0"
   resolved "https://registry.yarnpkg.com/convert-source-map/-/convert-source-map-1.7.0.tgz#17a2cb882d7f77d3490585e2ce6c524424a3a442"
   integrity sha512-4FJkXzKXEDB1snCFZlLP4gpC3JILicCpGbzG9f9G7tGqGCzETQ2hWPrcinA9oU4wtf2biUaEH5065UnMeR33oA==
@@ -8301,6 +8322,11 @@ fs-minipass@^2.0.0:
   dependencies:
     minipass "^3.0.0"
 
+fs-readdir-recursive@^1.1.0:
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/fs-readdir-recursive/-/fs-readdir-recursive-1.1.0.tgz#e32fc030a2ccee44a6b5371308da54be0b397d27"
+  integrity sha512-GNanXlVr2pf02+sPN40XN8HG+ePaNcvM0q5mZBd668Obwb0yD5GiUbZOFgwn8kGMY6I3mdyDJzieUy3PTYyTRA==
+
 fs-write-stream-atomic@^1.0.8:
   version "1.0.10"
   resolved "https://registry.yarnpkg.com/fs-write-stream-atomic/-/fs-write-stream-atomic-1.0.10.tgz#b47df53493ef911df75731e70a9ded0189db40c9"