refactor: remove a few Lodash usages & ESLint enforcement

.eslintrc.js

@@ -129,11 +129,36 @@ module.exports = {
     'no-redeclare': OFF,
     '@typescript-eslint/no-redeclare': ERROR,
     '@typescript-eslint/no-empty-interface': [
-      'error',
+      ERROR,
       {
         allowSingleExtends: true,
       },
     ],
+    'no-restricted-imports': [
+      ERROR,
+      {
+        paths: [
+          {
+            name: 'lodash',
+            importNames: [
+              // 'compact', // TODO: TS doesn't make Boolean a narrowing function yet, so filter(Boolean) is problematic type-wise
+              'filter',
+              'flatten',
+              'flatMap',
+              'map',
+              'reduce',
+              'take',
+              'takeRight',
+              'head',
+              'tail',
+              'initial',
+              'last',
+            ],
+            message: 'These APIs have their ES counterparts.',
+          },
+        ],
+      },
+    ],
   },
   overrides: [
     {

packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {flatten, uniqBy, difference, groupBy} from 'lodash';
+import {uniqBy, difference, groupBy} from 'lodash';
 import {
   PluginContext,
   RedirectMetadata,
@@ -165,7 +165,7 @@ function createRedirectsOptionRedirects(
     }));
   }
 
-  return flatten(redirectsOption.map(optionToRedirects));
+  return redirectsOption.flatMap(optionToRedirects);
 }
 
 // Create redirects from the "createRedirects" fn provided by the user
@@ -189,5 +189,5 @@ function createCreateRedirectsOptionRedirects(
     });
   }
 
-  return flatten(paths.map(createPathRedirects));
+  return paths.flatMap(createPathRedirects);
 }

packages/docusaurus-plugin-client-redirects/src/extensionRedirects.ts

@@ -5,7 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {flatten} from 'lodash';
 import {
   addTrailingSlash,
   removeSuffix,
@@ -62,7 +61,7 @@ export function createToExtensionsRedirects(
     return [];
   };
 
-  return flatten(paths.map(createPathRedirects));
+  return paths.flatMap(createPathRedirects);
 }
 
 // Create new /path.html/index.html that redirects to existing an /path
@@ -99,5 +98,5 @@ export function createFromExtensionsRedirects(
     }));
   };
 
-  return flatten(paths.map(createPathRedirects));
+  return paths.flatMap(createPathRedirects);
 }

packages/docusaurus-plugin-content-blog/src/blogUtils.ts

@@ -9,7 +9,7 @@ import fs from 'fs-extra';
 import chalk from 'chalk';
 import path from 'path';
 import readingTime from 'reading-time';
-import {compact, keyBy, mapValues} from 'lodash';
+import {keyBy, mapValues} from 'lodash';
 import {
   PluginOptions,
   BlogPost,
@@ -267,7 +267,7 @@ export async function generateBlogPosts(
     authorsMapPath: options.authorsMapPath,
   });
 
-  const blogPosts: BlogPost[] = compact(
+  const blogPosts = (
     await Promise.all(
       blogSourceFiles.map(async (blogSourceFile: string) => {
         try {
@@ -287,8 +287,8 @@ export async function generateBlogPosts(
           throw e;
         }
       }),
-    ),
-  );
+    )
+  ).filter(Boolean) as BlogPost[];
 
   blogPosts.sort(
     (a, b) => b.metadata.date.getTime() - a.metadata.date.getTime(),

packages/docusaurus-plugin-content-blog/src/index.ts

@@ -22,7 +22,6 @@ import {
   DEFAULT_PLUGIN_ID,
 } from '@docusaurus/core/lib/constants';
 import {translateContent, getTranslationFiles} from './translations';
-import {flatten, take} from 'lodash';
 
 import {
   PluginOptions,
@@ -98,10 +97,8 @@ export default function pluginContentBlog(
 
     getPathsToWatch() {
       const {include, authorsMapPath} = options;
-      const contentMarkdownGlobs = flatten(
-        getContentPathList(contentPaths).map((contentPath) => {
-          return include.map((pattern) => `${contentPath}/${pattern}`);
-        }),
+      const contentMarkdownGlobs = getContentPathList(contentPaths).flatMap(
+        (contentPath) => include.map((pattern) => `${contentPath}/${pattern}`),
       );
 
       // TODO: we should read this path in plugin! but plugins do not support async init for now :'(
@@ -244,7 +241,7 @@ export default function pluginContentBlog(
       const sidebarBlogPosts =
         options.blogSidebarCount === 'ALL'
           ? blogPosts
-          : take(blogPosts, options.blogSidebarCount);
+          : blogPosts.slice(0, options.blogSidebarCount);
 
       const archiveUrl = normalizeUrl([
         baseUrl,

packages/docusaurus-plugin-content-docs/src/index.ts

@@ -42,7 +42,7 @@ import {
 import {RuleSetRule} from 'webpack';
 import {cliDocsVersionCommand} from './cli';
 import {VERSIONS_JSON_FILE} from './constants';
-import {keyBy, compact, mapValues} from 'lodash';
+import {keyBy, mapValues} from 'lodash';
 import {toGlobalDataVersion} from './globalData';
 import {toTagDocListProp, toVersionMetadataProp} from './props';
 import {
@@ -388,7 +388,7 @@ export default function pluginContentDocs(
           include: contentDirs
             // Trailing slash is important, see https://github.com/facebook/docusaurus/pull/3970
             .map(addTrailingPathSeparator),
-          use: compact([
+          use: [
             getJSLoader({isServer}),
             {
               loader: require.resolve('@docusaurus/mdx-loader'),
@@ -414,7 +414,7 @@ export default function pluginContentDocs(
               loader: path.resolve(__dirname, './markdown/index.js'),
               options: docsMarkdownOptions,
             },
-          ]),
+          ].filter(Boolean),
         };
       }
 

packages/docusaurus-plugin-content-pages/src/index.ts

@@ -40,7 +40,6 @@ import {
   Metadata,
   PagesContentPaths,
 } from './types';
-import {flatten} from 'lodash';
 
 export function getContentPathList(contentPaths: PagesContentPaths): string[] {
   return [contentPaths.contentPathLocalized, contentPaths.contentPath];
@@ -86,10 +85,8 @@ export default function pluginContentPages(
 
     getPathsToWatch() {
       const {include = []} = options;
-      return flatten(
-        getContentPathList(contentPaths).map((contentPath) => {
-          return include.map((pattern) => `${contentPath}/${pattern}`);
-        }),
+      return getContentPathList(contentPaths).flatMap((contentPath) =>
+        include.map((pattern) => `${contentPath}/${pattern}`),
       );
     },
 

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

@@ -13,18 +13,16 @@ import {
   Footer,
 } from '@docusaurus/theme-common';
 
-import {keyBy, chain, flatten} from 'lodash';
+import {keyBy, chain} from 'lodash';
 import {mergeTranslations} from '@docusaurus/utils';
 
 function getNavbarTranslationFile(navbar: Navbar): TranslationFileContent {
   // TODO handle properly all the navbar item types here!
   function flattenNavbarItems(items: NavbarItem[]): NavbarItem[] {
-    const subItems = flatten(
-      items.map((item) => {
-        const allSubItems = flatten([item.items ?? []]);
-        return flattenNavbarItems(allSubItems);
-      }),
-    );
+    const subItems = items.flatMap((item) => {
+      const allSubItems = [item.items ?? []].flat();
+      return flattenNavbarItems(allSubItems);
+    });
     return [...items, ...subItems];
   }
 
@@ -84,9 +82,7 @@ function getFooterTranslationFile(footer: Footer): TranslationFileContent {
     .value();
 
   const footerLinkLabels: TranslationFileContent = chain(
-    flatten(footer.links.map((link) => link.items)).filter(
-      (link) => !!link.label,
-    ),
+    footer.links.flatMap((link) => link.items).filter((link) => !!link.label),
   )
     .keyBy((linkItem) => `link.item.label.${linkItem.label}`)
     .mapValues((linkItem) => ({

packages/docusaurus/src/server/brokenLinks.ts

@@ -8,7 +8,7 @@
 import {matchRoutes, RouteConfig as RRRouteConfig} from 'react-router-config';
 import resolvePathname from 'resolve-pathname';
 import fs from 'fs-extra';
-import {mapValues, pickBy, flatten, countBy} from 'lodash';
+import {mapValues, pickBy, countBy} from 'lodash';
 import {RouteConfig, ReportingSeverity} from '@docusaurus/types';
 import {removePrefix, removeSuffix, reportMessage} from '@docusaurus/utils';
 import {getAllFinalRoutes} from './utils';
@@ -110,10 +110,9 @@ export function getBrokenLinksErrorMessage(
   // Add an additional message in such case to help user figure this out.
   // see https://github.com/facebook/docusaurus/issues/3567#issuecomment-706973805
   function getLayoutBrokenLinksHelpMessage() {
-    const flatList = flatten(
-      Object.entries(allBrokenLinks).map(([pagePage, brokenLinks]) =>
+    const flatList = Object.entries(allBrokenLinks).flatMap(
+      ([pagePage, brokenLinks]) =>
         brokenLinks.map((brokenLink) => ({pagePage, brokenLink})),
-      ),
     );
 
     const countedBrokenLinks = countBy(

packages/docusaurus/src/server/translations/translationsExtractor.ts

@@ -9,7 +9,6 @@ import traverse, {Node} from '@babel/traverse';
 import generate from '@babel/generator';
 import chalk from 'chalk';
 import {parse, types as t, NodePath, TransformOptions} from '@babel/core';
-import {flatten} from 'lodash';
 import {
   InitializedPlugin,
   TranslationFileContent,
@@ -69,7 +68,7 @@ async function getSourceCodeFilePaths(
   // The getPathsToWatch() generally returns the js/jsx/ts/tsx/md/mdx file paths
   // We can use this method as well to know which folders we should try to extract translations from
   // Hacky/implicit, but do we want to introduce a new lifecycle method for that???
-  const pluginsPaths = flatten(plugins.map(getPluginSourceCodeFilePaths));
+  const pluginsPaths = plugins.flatMap(getPluginSourceCodeFilePaths);
 
   const allPaths = [...sitePaths, ...pluginsPaths];
 
@@ -133,11 +132,9 @@ export async function extractAllSourceCodeFileTranslations(
   sourceCodeFilePaths: string[],
   babelOptions: TransformOptions,
 ): Promise<SourceCodeFileTranslations[]> {
-  return flatten(
-    await Promise.all(
-      sourceCodeFilePaths.map((sourceFilePath) =>
-        extractSourceCodeFileTranslations(sourceFilePath, babelOptions),
-      ),
+  return Promise.all(
+    sourceCodeFilePaths.flatMap((sourceFilePath) =>
+      extractSourceCodeFileTranslations(sourceFilePath, babelOptions),
     ),
   );
 }

packages/docusaurus/src/server/utils.ts

@@ -4,17 +4,17 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-import {flatMap} from 'lodash';
+
 import {RouteConfig} from '@docusaurus/types';
 import nodePath from 'path';
 import {posixPath, Globby} from '@docusaurus/utils';
 
 // Recursively get the final routes (routes with no subroutes)
 export function getAllFinalRoutes(routeConfig: RouteConfig[]): RouteConfig[] {
   function getFinalRoutes(route: RouteConfig): RouteConfig[] {
-    return route.routes ? flatMap(route.routes, getFinalRoutes) : [route];
+    return route.routes ? route.routes.flatMap(getFinalRoutes) : [route];
   }
-  return flatMap(routeConfig, getFinalRoutes);
+  return routeConfig.flatMap(getFinalRoutes);
 }
 
 // Globby that fix Windows path patterns

website/tsconfig.json

@@ -2,6 +2,7 @@
   // This file is not used in compilation. It is here just for a nice editor experience.
   "extends": "@tsconfig/docusaurus/tsconfig.json",
   "compilerOptions": {
+    "lib": ["DOM", "ESNext"],
     "baseUrl": ".",
     "resolveJsonModule": true
   },