chore: Enable ESLint rules of hooks + fix new lint errors (#5714)

.eslintrc.js

@@ -28,6 +28,7 @@ module.exports = {
     'eslint:recommended',
     'plugin:@typescript-eslint/eslint-recommended',
     'plugin:@typescript-eslint/recommended',
+    'plugin:react-hooks/recommended',
     'airbnb',
     'prettier',
     'prettier/react',
@@ -41,6 +42,8 @@ module.exports = {
   },
   plugins: ['react-hooks', 'header'],
   rules: {
+    'react-hooks/rules-of-hooks': ERROR,
+    'react-hooks/exhaustive-deps': ERROR,
     'class-methods-use-this': OFF, // It's a way of allowing private variables.
     'func-names': OFF,
     // Ignore certain webpack alias because it can't be resolved
@@ -77,7 +80,6 @@ module.exports = {
     'react/destructuring-assignment': OFF, // Too many lines.
     'react/prefer-stateless-function': WARNING,
     'react/jsx-props-no-spreading': OFF,
-    'react-hooks/rules-of-hooks': ERROR,
     'react/require-default-props': [ERROR, {ignoreFunctionalComponents: true}],
     '@typescript-eslint/no-inferrable-types': OFF,
     'import/first': OFF,

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

@@ -51,7 +51,7 @@ function DocPageContent({
       setHiddenSidebar(false);
     }
 
-    setHiddenSidebarContainer(!hiddenSidebarContainer);
+    setHiddenSidebarContainer((value) => !value);
   }, [hiddenSidebar]);
 
   return (

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

@@ -93,7 +93,7 @@ function useAutoExpandActiveCategory({
     if (justBecameActive && collapsed) {
       setCollapsed(false);
     }
-  }, [isActive, wasActive, collapsed]);
+  }, [isActive, wasActive, collapsed, setCollapsed]);
 }
 
 function DocSidebarItemCategory({

packages/docusaurus-theme-classic/src/theme/NavbarItem/DropdownNavbarItem.tsx

@@ -141,7 +141,7 @@ function DropdownNavbarItemMobile({
     if (containsActive) {
       setCollapsed(!containsActive);
     }
-  }, [localPathname, containsActive]);
+  }, [localPathname, containsActive, setCollapsed]);
 
   return (
     <li

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

@@ -68,7 +68,7 @@ const useTheme = (): useThemeReturns => {
     } catch (err) {
       console.error(err);
     }
-  }, [setTheme]);
+  }, [disableSwitch, setTheme]);
 
   useEffect(() => {
     if (disableSwitch && !respectPrefersColorScheme) {
@@ -80,7 +80,7 @@ const useTheme = (): useThemeReturns => {
       .addListener(({matches}) => {
         setTheme(matches ? themes.dark : themes.light);
       });
-  }, []);
+  }, [disableSwitch, respectPrefersColorScheme]);
 
   return {
     isDarkTheme: theme === themes.dark,

packages/docusaurus-theme-common/src/index.ts

@@ -88,3 +88,8 @@ export {
   useScrollPosition,
   useScrollPositionBlocker,
 } from './utils/scrollUtils';
+
+export {
+  useIsomorphicLayoutEffect,
+  useDynamicCallback,
+} from './utils/reactUtils';

packages/docusaurus-theme-common/src/utils/announcementBarUtils.tsx

@@ -83,14 +83,14 @@ const useAnnouncementBarContextValue = (): AnnouncementBarAPI => {
     if (isNewAnnouncement || !isDismissedInStorage()) {
       setClosed(false);
     }
-  }, []);
+  }, [announcementBar]);
 
   return useMemo(() => {
     return {
       isActive: !!announcementBar && !isClosed,
       close: handleClose,
     };
-  }, [isClosed]);
+  }, [announcementBar, isClosed, handleClose]);
 };
 
 const AnnouncementBarContext = createContext<AnnouncementBarAPI | null>(null);

packages/docusaurus-theme-common/src/utils/docsPreferredVersion/DocsPreferredVersionProvider.tsx

@@ -120,7 +120,7 @@ function useContextValue() {
     return {
       savePreferredVersion,
     };
-  }, [setState]);
+  }, [versionPersistence]);
 
   return [state, api] as const;
 }

packages/docusaurus-theme-common/src/utils/docsPreferredVersion/useDocsPreferredVersion.ts

@@ -30,7 +30,7 @@ export function useDocsPreferredVersion(
     (versionName: string) => {
       api.savePreferredVersion(pluginId, versionName);
     },
-    [api],
+    [api, pluginId],
   );
 
   return {preferredVersion, savePreferredVersionName} as const;

packages/docusaurus-theme-common/src/utils/mobileSecondaryMenu.tsx

@@ -83,6 +83,7 @@ function useShallowMemoizedObject<O extends Record<string, unknown>>(obj: O) {
   return useMemo(
     () => obj,
     // Is this safe?
+    // eslint-disable-next-line react-hooks/exhaustive-deps
     [...Object.keys(obj), ...Object.values(obj)],
   );
 }

packages/docusaurus-theme-common/src/utils/reactUtils.tsx

@@ -0,0 +1,34 @@
+/**
+ * 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.
+ */
+
+import {useCallback, useEffect, useLayoutEffect, useRef} from 'react';
+
+// This hook is like useLayoutEffect, but without the SSR warning
+// It seems hacky but it's used in many React libs (Redux, Formik...)
+// Also mentioned here: https://github.com/facebook/react/issues/16956
+// It is useful when you need to update a ref as soon as possible after a React render (before useEffect)
+export const useIsomorphicLayoutEffect =
+  typeof window !== 'undefined' ? useLayoutEffect : useEffect;
+
+// Permits to transform an unstable callback (like an arrow function provided as props)
+// to a "stable" callback that is safe to use in a useEffect dependency array
+// Useful to avoid React stale closure problems + avoid useless effect re-executions
+//
+// Workaround until the React team recommends a good solution, see https://github.com/facebook/react/issues/16956
+// This generally works has some potential drawbacks, such as https://github.com/facebook/react/issues/16956#issuecomment-536636418
+export function useDynamicCallback<T extends (...args: never[]) => unknown>(
+  callback: T,
+): T {
+  const ref = useRef<T>(callback);
+
+  useIsomorphicLayoutEffect(() => {
+    ref.current = callback;
+  }, [callback]);
+
+  // @ts-expect-error: TODO, not sure how to fix this TS error
+  return useCallback<T>((...args) => ref.current(...args), []);
+}

packages/docusaurus-theme-common/src/utils/scrollUtils.tsx

@@ -15,6 +15,7 @@ import React, {
   useMemo,
   useRef,
 } from 'react';
+import {useDynamicCallback} from './reactUtils';
 import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
 
 /**
@@ -103,20 +104,22 @@ export function useScrollPosition(
   const {scrollEventsEnabledRef} = useScrollController();
   const lastPositionRef = useRef<ScrollPosition | null>(getScrollPosition());
 
+  const dynamicEffect = useDynamicCallback(effect);
+
+  useEffect(() => {
     const handleScroll = () => {
       if (!scrollEventsEnabledRef.current) {
         return;
       }
       const currentPosition = getScrollPosition()!;
 
-    if (effect) {
+      if (dynamicEffect) {
-      effect(currentPosition, lastPositionRef.current);
+        dynamicEffect(currentPosition, lastPositionRef.current);
       }
 
       lastPositionRef.current = currentPosition;
     };
 
-  useEffect(() => {
     const opts: AddEventListenerOptions & EventListenerOptions = {
       passive: true,
     };
@@ -125,7 +128,12 @@ export function useScrollPosition(
     window.addEventListener('scroll', handleScroll, opts);
 
     return () => window.removeEventListener('scroll', handleScroll, opts);
-  }, deps);
+  }, [
+    dynamicEffect,
+    scrollEventsEnabledRef,
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+    ...deps,
+  ]);
 }
 
 type UseScrollPositionSaver = {
@@ -170,7 +178,7 @@ function useScrollPositionSaver(): UseScrollPositionSaver {
     return {restored: heightDiff !== 0};
   }, []);
 
-  return useMemo(() => ({save, restore}), []);
+  return useMemo(() => ({save, restore}), [restore, save]);
 }
 
 type UseScrollPositionBlockerReturn = {
@@ -217,7 +225,7 @@ export function useScrollPositionBlocker(): UseScrollPositionBlockerReturn {
         }
       };
     },
-    [scrollController],
+    [scrollController, scrollPositionSaver],
   );
 
   useLayoutEffect(() => {

packages/docusaurus-theme-common/src/utils/useLocationChange.ts

@@ -9,6 +9,7 @@ import {useEffect} from 'react';
 import {useLocation} from '@docusaurus/router';
 import {Location} from '@docusaurus/history';
 import {usePrevious} from './usePrevious';
+import {useDynamicCallback} from './reactUtils';
 
 type LocationChangeEvent = {
   location: Location;
@@ -21,10 +22,12 @@ export function useLocationChange(onLocationChange: OnLocationChange): void {
   const location = useLocation();
   const previousLocation = usePrevious(location);
 
+  const onLocationChangeDynamic = useDynamicCallback(onLocationChange);
+
   useEffect(() => {
-    onLocationChange({
+    onLocationChangeDynamic({
       location,
       previousLocation,
     });
-  }, [location]);
+  }, [onLocationChangeDynamic, location, previousLocation]);
 }

packages/docusaurus-theme-common/src/utils/usePrevious.ts

@@ -5,12 +5,13 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {useRef, useEffect} from 'react';
+import {useRef} from 'react';
+import {useIsomorphicLayoutEffect} from './reactUtils';
 
 export function usePrevious<T>(value: T): T | undefined {
   const ref = useRef<T>();
 
-  useEffect(() => {
+  useIsomorphicLayoutEffect(() => {
     ref.current = value;
   });
 

packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.js

@@ -16,7 +16,11 @@ import clsx from 'clsx';
 import Head from '@docusaurus/Head';
 import Link from '@docusaurus/Link';
 import ExecutionEnvironment from '@docusaurus/ExecutionEnvironment';
-import {useTitleFormatter, usePluralForm} from '@docusaurus/theme-common';
+import {
+  useTitleFormatter,
+  usePluralForm,
+  useDynamicCallback,
+} from '@docusaurus/theme-common';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 import {useAllDocsData} from '@theme/hooks/useDocs';
 import useSearchQuery from '@theme/hooks/useSearchQuery';
@@ -173,6 +177,7 @@ function SearchPage() {
     },
     initialSearchResultState,
   );
+
   const algoliaClient = algoliaSearch(appId, apiKey);
   const algoliaHelper = algoliaSearchHelper(algoliaClient, indexName, {
     hitsPerPage: 15,
@@ -271,7 +276,7 @@ function SearchPage() {
           description: 'The search page title for empty query',
         });
 
-  const makeSearch = (page = 0) => {
+  const makeSearch = useDynamicCallback((page = 0) => {
     algoliaHelper.addDisjunctiveFacetRefinement('docusaurus_tag', 'default');
     algoliaHelper.addDisjunctiveFacetRefinement('language', currentLocale);
 
@@ -285,18 +290,16 @@ function SearchPage() {
     );
 
     algoliaHelper.setQuery(searchQuery).setPage(page).search();
-  };
+  });
 
   useEffect(() => {
     if (!loaderRef) {
       return undefined;
     }
+    const currentObserver = observer.current;
 
-    observer.current.observe(loaderRef);
+    currentObserver.observe(loaderRef);
-
+    return () => currentObserver.unobserve(loaderRef);
-    return () => {
-      observer.current.unobserve(loaderRef);
-    };
   }, [loaderRef]);
 
   useEffect(() => {
@@ -311,7 +314,12 @@ function SearchPage() {
         makeSearch();
       }, 300);
     }
-  }, [searchQuery, docsSearchVersionsHelpers.searchVersions]);
+  }, [
+    searchQuery,
+    docsSearchVersionsHelpers.searchVersions,
+    updateSearchPath,
+    makeSearch,
+  ]);
 
   useEffect(() => {
     if (!searchResultState.lastPage || searchResultState.lastPage === 0) {
@@ -319,13 +327,13 @@ function SearchPage() {
     }
 
     makeSearch(searchResultState.lastPage);
-  }, [searchResultState.lastPage]);
+  }, [makeSearch, searchResultState.lastPage]);
 
   useEffect(() => {
     if (searchValue && searchValue !== searchQuery) {
       setSearchQuery(searchValue);
     }
-  }, [searchValue]);
+  }, [searchQuery, searchValue]);
 
   return (
     <Layout wrapperClassName="search-page-wrapper">

packages/docusaurus/src/client/exports/Link.tsx

@@ -90,16 +90,16 @@ function Link({
 
   const IOSupported = ExecutionEnvironment.canUseIntersectionObserver;
 
-  let io: IntersectionObserver;
+  const ioRef = useRef<IntersectionObserver>();
   const handleIntersection = (el: HTMLAnchorElement, cb: () => void) => {
-    io = new window.IntersectionObserver((entries) => {
+    ioRef.current = new window.IntersectionObserver((entries) => {
       entries.forEach((entry) => {
         if (el === entry.target) {
           // If element is in viewport, stop listening/observing and run callback.
           // https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
           if (entry.isIntersecting || entry.intersectionRatio > 0) {
-            io.unobserve(el);
+            ioRef.current!.unobserve(el);
-            io.disconnect();
+            ioRef.current!.disconnect();
             cb();
           }
         }
@@ -107,7 +107,7 @@ function Link({
     });
 
     // Add element to the observer.
-    io.observe(el);
+    ioRef.current!.observe(el);
   };
 
   const handleRef = (ref: HTMLAnchorElement | null) => {
@@ -138,11 +138,11 @@ function Link({
 
     // When unmounting, stop intersection observer from watching.
     return () => {
-      if (IOSupported && io) {
+      if (IOSupported && ioRef.current) {
-        io.disconnect();
+        ioRef.current.disconnect();
       }
     };
-  }, [targetLink, IOSupported, isInternal]);
+  }, [ioRef, targetLink, IOSupported, isInternal]);
 
   const isAnchorLink = targetLink?.startsWith('#') ?? false;
   const isRegularHtmlLink = !targetLink || !isInternal || isAnchorLink;