feat(theme-classic): auto-collapse sibling categories in doc sidebar

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

@@ -149,19 +149,13 @@ declare module '@theme/DocSidebar' {
 declare module '@theme/DocSidebarItem' {
   import type {PropSidebarItem} from '@docusaurus/plugin-content-docs';
 
-  export type DocSidebarPropsBase = {
-    readonly activePath: string;
-    readonly onItemClick?: (item: PropSidebarItem) => void;
-    readonly level: number;
-    readonly tabIndex?: number;
-  };
-
   export interface Props {
     readonly activePath: string;
     readonly onItemClick?: (item: PropSidebarItem) => void;
     readonly level: number;
     readonly tabIndex?: number;
     readonly item: PropSidebarItem;
+    readonly index: number;
   }
 
   export default function DocSidebarItem(props: Props): JSX.Element;
@@ -171,7 +165,7 @@ declare module '@theme/DocSidebarItems' {
   import type {Props as DocSidebarItemProps} from '@theme/DocSidebarItem';
   import type {PropSidebarItem} from '@docusaurus/plugin-content-docs';
 
-  export type Props = Omit<DocSidebarItemProps, 'item'> & {
+  export type Props = Omit<DocSidebarItemProps, 'item' | 'index'> & {
     readonly items: readonly PropSidebarItem[];
   };
 

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

@@ -14,6 +14,8 @@ import {
   useCollapsible,
   findFirstCategoryLink,
   ThemeClassNames,
+  useThemeConfig,
+  useDocSidebarItemsExpandedState,
 } from '@docusaurus/theme-common';
 import Link from '@docusaurus/Link';
 import isInternalUrl from '@docusaurus/isInternalUrl';
@@ -92,14 +94,15 @@ function DocSidebarItemCategory({
   onItemClick,
   activePath,
   level,
+  index,
   ...props
 }: Props & {item: PropSidebarItemCategory}) {
   const {items, label, collapsible, className, href} = item;
   const hrefWithSSRFallback = useCategoryHrefWithSSRFallback(item);
 
   const isActive = isActiveSidebarItem(item, activePath);
 
-  const {collapsed, setCollapsed, toggleCollapsed} = useCollapsible({
+  const {collapsed, setCollapsed} = useCollapsible({
     // active categories are always initialized as expanded
     // the default (item.collapsed) is only used for non-active categories
     initialState: () => {
@@ -111,6 +114,28 @@ function DocSidebarItemCategory({
   });
 
   useAutoExpandActiveCategory({isActive, collapsed, setCollapsed});
+  const {expandedItem, setExpandedItem} = useDocSidebarItemsExpandedState();
+  function updateCollapsed(toCollapsed: boolean = !collapsed) {
+    setExpandedItem(toCollapsed ? null : index);
+    setCollapsed(toCollapsed);
+  }
+  const {autoCollapseSidebarCategories} = useThemeConfig();
+  useEffect(() => {
+    if (
+      collapsible &&
+      expandedItem &&
+      expandedItem !== index &&
+      autoCollapseSidebarCategories
+    ) {
+      setCollapsed(true);
+    }
+  }, [
+    collapsible,
+    expandedItem,
+    index,
+    setCollapsed,
+    autoCollapseSidebarCategories,
+  ]);
 
   return (
     <li
@@ -136,10 +161,10 @@ function DocSidebarItemCategory({
               ? (e) => {
                   onItemClick?.(item);
                   if (href) {
-                    setCollapsed(false);
+                    updateCollapsed(false);
                   } else {
                     e.preventDefault();
-                    toggleCollapsed();
+                    updateCollapsed();
                   }
                 }
               : () => {
@@ -165,7 +190,7 @@ function DocSidebarItemCategory({
             className="clean-btn menu__caret"
             onClick={(e) => {
               e.preventDefault();
-              toggleCollapsed();
+              updateCollapsed();
             }}
           />
         )}
@@ -189,6 +214,7 @@ function DocSidebarItemLink({
   onItemClick,
   activePath,
   level,
+  index,
   ...props
 }: Props & {item: PropSidebarItemLink}) {
   const {href, label, className} = item;

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

@@ -6,24 +6,25 @@
  */
 
 import React, {memo} from 'react';
-
 import DocSidebarItem from '@theme/DocSidebarItem';
+import {DocSidebarItemsExpandedStateProvider} from '@docusaurus/theme-common';
 
 import type {Props} from '@theme/DocSidebarItems';
 
 // TODO this item should probably not receive the "activePath" props
 // TODO this triggers whole sidebar re-renders on navigation
 function DocSidebarItems({items, ...props}: Props): JSX.Element {
   return (
-    <>
+    <DocSidebarItemsExpandedStateProvider>
       {items.map((item, index) => (
         <DocSidebarItem
           key={index} // sidebar is static, the index does not change
           item={item}
+          index={index}
           {...props}
         />
       ))}
-    </>
+    </DocSidebarItemsExpandedStateProvider>
   );
 }
 

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

@@ -41,6 +41,7 @@ const DEFAULT_CONFIG = {
     items: [],
   },
   hideableSidebar: false,
+  autoCollapseSidebarCategories: false,
   tableOfContents: {
     minHeadingLevel: 2,
     maxHeadingLevel: 3,
@@ -352,6 +353,9 @@ const ThemeConfigSchema = Joi.object({
     .default(DEFAULT_CONFIG.prism)
     .unknown(),
   hideableSidebar: Joi.bool().default(DEFAULT_CONFIG.hideableSidebar),
+  autoCollapseSidebarCategories: Joi.bool().default(
+    DEFAULT_CONFIG.autoCollapseSidebarCategories,
+  ),
   sidebarCollapsible: Joi.forbidden().messages({
     'any.unknown':
       'The themeConfig.sidebarCollapsible has been moved to docs plugin options. See: https://docusaurus.io/docs/api/plugins/@docusaurus/plugin-content-docs',

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

@@ -6,6 +6,10 @@
  */
 
 export {useThemeConfig} from './utils/useThemeConfig';
+export {
+  DocSidebarItemsExpandedStateProvider,
+  useDocSidebarItemsExpandedState,
+} from './utils/docSidebarItemsExpandedState';
 
 export type {
   ThemeConfig,

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

@@ -0,0 +1,41 @@
+/**
+ * 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 React, {type ReactNode, useMemo, useState, useContext} from 'react';
+
+const EmptyContext: unique symbol = Symbol('EmptyContext');
+const Context = React.createContext<
+  DocSidebarItemsExpandedState | typeof EmptyContext
+>(EmptyContext);
+type DocSidebarItemsExpandedState = {
+  expandedItem: number | null;
+  setExpandedItem: (a: number | null) => void;
+};
+
+export function DocSidebarItemsExpandedStateProvider({
+  children,
+}: {
+  children: ReactNode;
+}): JSX.Element {
+  const [expandedItem, setExpandedItem] = useState<number | null>(null);
+  const contextValue = useMemo(
+    () => ({expandedItem, setExpandedItem}),
+    [expandedItem],
+  );
+
+  return <Context.Provider value={contextValue}>{children}</Context.Provider>;
+}
+
+export function useDocSidebarItemsExpandedState(): DocSidebarItemsExpandedState {
+  const contextValue = useContext(Context);
+  if (contextValue === EmptyContext) {
+    throw new Error(
+      'This hook requires usage of <DocSidebarItemsExpandedStateProvider>',
+    );
+  }
+  return contextValue;
+}

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

@@ -122,6 +122,7 @@ export type ThemeConfig = {
   prism: PrismConfig;
   footer?: Footer;
   hideableSidebar: boolean;
+  autoCollapseSidebarCategories: boolean;
   image?: string;
   metadata: Array<Record<string, string>>;
   sidebarCollapsible: boolean;

website/docs/api/docusaurus.config.js.md

@@ -276,6 +276,7 @@ Example:
 module.exports = {
   themeConfig: {
     hideableSidebar: false,
+    autoCollapseSidebarCategories: false,
     colorMode: {
       defaultMode: 'light',
       disableSwitch: false,

website/docs/guides/docs/sidebar.md

@@ -913,7 +913,9 @@ module.exports = {
 
 :::
 
-## Hideable sidebar {#hideable-sidebar}
+## Theme configuration
+
+### Hideable sidebar {#hideable-sidebar}
 
 By enabling the `themeConfig.hideableSidebar` option, you can make the entire sidebar hideable, allowing users to better focus on the content. This is especially useful when content is consumed on medium-sized screens (e.g. tablets).
 
@@ -927,6 +929,19 @@ module.exports = {
 };
 ```
 
+### Auto-collapse sidebar categories
+
+The `themeConfig.autoCollapseSidebarCategories` option would collapse all sibling categories when expanding one category. This saves the user from having too many categories open and helps them focus on the selected section.
+
+```js title="docusaurus.config.js"
+module.exports = {
+  themeConfig: {
+    // highlight-next-line
+    autoCollapseSidebarCategories: true,
+  },
+};
+```
+
 ## Using multiple sidebars {#using-multiple-sidebars}
 
 You can create a sidebar for each **set of Markdown files** that you want to **group together**.

website/docusaurus.config.js

@@ -317,6 +317,7 @@ const config = {
         playgroundPosition: 'bottom',
       },
       hideableSidebar: true,
+      autoCollapseSidebarCategories: true,
       colorMode: {
         defaultMode: 'light',
         disableSwitch: false,