From 8e934450d88775acac0ec28089e8cf8b1e548138 Mon Sep 17 00:00:00 2001
From: Joshua Chen <sidachen2003@gmail.com>
Date: Mon, 7 Mar 2022 19:23:30 +0800
Subject: [PATCH] refactor: remove unnecessary default values normalized during
 validation (#6864)

* refactor: remove unnecessary default values normalized during validation

* more
---
 packages/docusaurus-mdx-loader/src/index.ts   | 10 +--
 .../src/collectRedirects.ts                   |  4 +-
 .../src/index.ts                              | 12 ++--
 .../src/versions.ts                           |  2 +-
 .../src/index.ts                              |  4 +-
 packages/docusaurus-plugin-pwa/src/index.ts   |  2 +-
 .../docusaurus-theme-classic/src/index.ts     |  7 +-
 .../src/theme/BlogArchivePage/index.tsx       | 13 ++--
 .../src/theme/Footer/index.tsx                | 72 ++++++++-----------
 .../src/theme/ThemedImage/index.tsx           |  2 +-
 .../src/validateThemeConfig.ts                |  2 +-
 .../src/utils/useThemeConfig.ts               |  4 +-
 packages/docusaurus-types/src/index.d.ts      | 12 ++--
 .../src/client/exports/BrowserOnly.tsx        |  2 +-
 .../docusaurus/src/client/exports/Link.tsx    |  2 +-
 .../docusaurus/src/client/serverEntry.tsx     |  8 +--
 .../docusaurus/src/commands/commandUtils.ts   |  2 +-
 packages/docusaurus/src/commands/start.ts     | 11 ++-
 .../__snapshots__/config.test.ts.snap         | 12 ++++
 .../docusaurus/src/server/configValidation.ts | 48 ++++++++-----
 .../src/server/html-tags/htmlTags.ts          |  2 +-
 .../docusaurus/src/server/html-tags/index.ts  |  2 +-
 packages/docusaurus/src/server/index.ts       | 38 +++++-----
 .../server/presets/__tests__/index.test.ts    |  4 +-
 .../docusaurus/src/server/presets/index.ts    |  3 +-
 .../src/webpack/plugins/CleanWebpackPlugin.ts |  2 +-
 packages/lqip-loader/src/index.ts             |  2 +-
 27 files changed, 146 insertions(+), 138 deletions(-)

diff --git a/packages/docusaurus-mdx-loader/src/index.ts b/packages/docusaurus-mdx-loader/src/index.ts
index 7a704ef847..4188651a09 100644
--- a/packages/docusaurus-mdx-loader/src/index.ts
+++ b/packages/docusaurus-mdx-loader/src/index.ts
@@ -114,7 +114,7 @@ export default async function mdxLoader(
 ): Promise<void> {
   const callback = this.async();
   const filePath = this.resourcePath;
-  const reqOptions = this.getOptions() || {};
+  const reqOptions = this.getOptions() ?? {};
 
   const {frontMatter, content: contentWithTitle} = parseFrontMatter(fileString);
 
@@ -127,7 +127,7 @@ export default async function mdxLoader(
   const options: Options = {
     ...reqOptions,
     remarkPlugins: [
-      ...(reqOptions.beforeDefaultRemarkPlugins || []),
+      ...(reqOptions.beforeDefaultRemarkPlugins ?? []),
       ...DEFAULT_OPTIONS.remarkPlugins,
       [
         transformImage,
@@ -143,12 +143,12 @@ export default async function mdxLoader(
           siteDir: reqOptions.siteDir,
         },
       ],
-      ...(reqOptions.remarkPlugins || []),
+      ...(reqOptions.remarkPlugins ?? []),
     ],
     rehypePlugins: [
-      ...(reqOptions.beforeDefaultRehypePlugins || []),
+      ...(reqOptions.beforeDefaultRehypePlugins ?? []),
       ...DEFAULT_OPTIONS.rehypePlugins,
-      ...(reqOptions.rehypePlugins || []),
+      ...(reqOptions.rehypePlugins ?? []),
     ],
     filepath: filePath,
   };
diff --git a/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts b/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts
index 6ffd68da51..1ffb8e568e 100644
--- a/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts
+++ b/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts
@@ -166,9 +166,7 @@ function createCreateRedirectsOptionRedirects(
   createRedirects: PluginOptions['createRedirects'],
 ): RedirectMetadata[] {
   function createPathRedirects(path: string): RedirectMetadata[] {
-    const fromsMixed: string | string[] = createRedirects
-      ? createRedirects(path) || []
-      : [];
+    const fromsMixed: string | string[] = createRedirects?.(path) ?? [];
 
     const froms: string[] =
       typeof fromsMixed === 'string' ? [fromsMixed] : fromsMixed;
diff --git a/packages/docusaurus-plugin-content-blog/src/index.ts b/packages/docusaurus-plugin-content-blog/src/index.ts
index a1f92f23e9..2027f068ff 100644
--- a/packages/docusaurus-plugin-content-blog/src/index.ts
+++ b/packages/docusaurus-plugin-content-blog/src/index.ts
@@ -546,13 +546,11 @@ export default async function pluginContentBlog(
       const headTags: HtmlTags = [];
 
       feedTypes.forEach((feedType) => {
-        const feedConfig = feedsConfig[feedType] || {};
-
-        if (!feedsConfig) {
-          return;
-        }
-
-        const {type, path: feedConfigPath, title: feedConfigTitle} = feedConfig;
+        const {
+          type,
+          path: feedConfigPath,
+          title: feedConfigTitle,
+        } = feedsConfig[feedType];
 
         headTags.push({
           tagName: 'link',
diff --git a/packages/docusaurus-plugin-content-docs/src/versions.ts b/packages/docusaurus-plugin-content-docs/src/versions.ts
index 26fd63773c..08dbb0a796 100644
--- a/packages/docusaurus-plugin-content-docs/src/versions.ts
+++ b/packages/docusaurus-plugin-content-docs/src/versions.ts
@@ -537,7 +537,7 @@ export function filterVersions(
 ): string[] {
   if (options.onlyIncludeVersions) {
     return versionNamesUnfiltered.filter((name) =>
-      (options.onlyIncludeVersions || []).includes(name),
+      options.onlyIncludeVersions!.includes(name),
     );
   }
   return versionNamesUnfiltered;
diff --git a/packages/docusaurus-plugin-content-pages/src/index.ts b/packages/docusaurus-plugin-content-pages/src/index.ts
index 9cc4e389b4..d7f4c48f90 100644
--- a/packages/docusaurus-plugin-content-pages/src/index.ts
+++ b/packages/docusaurus-plugin-content-pages/src/index.ts
@@ -47,7 +47,7 @@ export default async function pluginContentPages(
 ): Promise<Plugin<LoadedContent | null>> {
   if (options.admonitions) {
     options.remarkPlugins = options.remarkPlugins.concat([
-      [admonitions, options.admonitions || {}],
+      [admonitions, options.admonitions],
     ]);
   }
   const {
@@ -77,7 +77,7 @@ export default async function pluginContentPages(
     name: 'docusaurus-plugin-content-pages',
 
     getPathsToWatch() {
-      const {include = []} = options;
+      const {include} = options;
       return getContentPathList(contentPaths).flatMap((contentPath) =>
         include.map((pattern) => `${contentPath}/${pattern}`),
       );
diff --git a/packages/docusaurus-plugin-pwa/src/index.ts b/packages/docusaurus-plugin-pwa/src/index.ts
index e099ec0411..fa94328d28 100644
--- a/packages/docusaurus-plugin-pwa/src/index.ts
+++ b/packages/docusaurus-plugin-pwa/src/index.ts
@@ -191,7 +191,7 @@ export default function pluginPWA(
           '**/*.{woff,woff2,eot,ttf,otf}',
           // eslint-disable-next-line @typescript-eslint/ban-ts-comment
           // @ts-ignore
-          ...(injectManifest.globPatterns || []),
+          ...(injectManifest.globPatterns ?? []),
         ],
         // those attributes are not overrideable
         swDest,
diff --git a/packages/docusaurus-theme-classic/src/index.ts b/packages/docusaurus-theme-classic/src/index.ts
index c401e48ddb..d5066c5d4f 100644
--- a/packages/docusaurus-theme-classic/src/index.ts
+++ b/packages/docusaurus-theme-classic/src/index.ts
@@ -97,16 +97,15 @@ export default function docusaurusThemeClassic(
   options: Options,
 ): Plugin<void> {
   const {
-    siteConfig: {themeConfig: roughlyTypedThemeConfig},
     i18n: {currentLocale, localeConfigs},
   } = context;
-  const themeConfig = (roughlyTypedThemeConfig || {}) as ThemeConfig;
+  const themeConfig = context.siteConfig.themeConfig as ThemeConfig;
   const {
     announcementBar,
     colorMode,
-    prism: {additionalLanguages = []} = {},
+    prism: {additionalLanguages},
   } = themeConfig;
-  const {customCss} = options || {};
+  const {customCss} = options ?? {};
   const {direction} = localeConfigs[currentLocale]!;
 
   return {
diff --git a/packages/docusaurus-theme-classic/src/theme/BlogArchivePage/index.tsx b/packages/docusaurus-theme-classic/src/theme/BlogArchivePage/index.tsx
index dda63da77c..f10c59b191 100644
--- a/packages/docusaurus-theme-classic/src/theme/BlogArchivePage/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/BlogArchivePage/index.tsx
@@ -50,14 +50,11 @@ function YearsSection({years}: {years: YearProp[]}) {
 }
 
 function listPostsByYears(blogPosts: readonly ArchiveBlogPost[]): YearProp[] {
-  const postsByYear: Map<string, ArchiveBlogPost[]> = blogPosts.reduceRight(
-    (posts, post) => {
-      const year = post.metadata.date.split('-')[0];
-      const yearPosts = posts.get(year) || [];
-      return posts.set(year, [post, ...yearPosts]);
-    },
-    new Map(),
-  );
+  const postsByYear = blogPosts.reduceRight((posts, post) => {
+    const year = post.metadata.date.split('-')[0]!;
+    const yearPosts = posts.get(year) ?? [];
+    return posts.set(year, [post, ...yearPosts]);
+  }, new Map<string, ArchiveBlogPost[]>());
 
   return Array.from(postsByYear, ([year, posts]) => ({
     year,
diff --git a/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx b/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx
index 8b53fb3f90..568c2022de 100644
--- a/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx
@@ -15,10 +15,10 @@ import {
   type MultiColumnFooter,
   type SimpleFooter,
 } from '@docusaurus/theme-common';
-import useBaseUrl from '@docusaurus/useBaseUrl';
+import useBaseUrl, {useBaseUrlUtils} from '@docusaurus/useBaseUrl';
 import isInternalUrl from '@docusaurus/isInternalUrl';
 import styles from './styles.module.css';
-import ThemedImage, {type Props as ThemedImageProps} from '@theme/ThemedImage';
+import ThemedImage from '@theme/ThemedImage';
 import IconExternalLink from '@theme/IconExternalLink';
 
 function FooterLink({
@@ -54,21 +54,35 @@ function FooterLink({
   );
 }
 
-function FooterLogo({
-  sources,
-  alt,
-  width,
-  height,
-}: Pick<ThemedImageProps, 'sources' | 'alt' | 'width' | 'height'>) {
-  return (
+function FooterLogo({logo}: {logo: SimpleFooter['logo']}) {
+  const {withBaseUrl} = useBaseUrlUtils();
+  if (!logo?.src) {
+    return null;
+  }
+  const sources = {
+    light: withBaseUrl(logo.src),
+    dark: withBaseUrl(logo.srcDark ?? logo.src),
+  };
+  const image = (
     <ThemedImage
       className="footer__logo"
-      alt={alt}
+      alt={logo.alt}
       sources={sources}
-      width={width}
-      height={height}
+      width={logo.width}
+      height={logo.height}
     />
   );
+  return (
+    <div className="margin-bottom--sm">
+      {logo.href ? (
+        <Link href={logo.href} className={styles.footerLogoLink}>
+          {image}
+        </Link>
+      ) : (
+        image
+      )}
+    </div>
+  );
 }
 
 function MultiColumnLinks({links}: {links: MultiColumnFooter['links']}) {
@@ -136,16 +150,10 @@ function isMultiColumnFooterLinks(
 
 function Footer(): JSX.Element | null {
   const {footer} = useThemeConfig();
-
-  const {copyright, links = [], logo = {}} = footer || {};
-  const sources = {
-    light: useBaseUrl(logo.src),
-    dark: useBaseUrl(logo.srcDark || logo.src),
-  };
-
   if (!footer) {
     return null;
   }
+  const {copyright, links, logo} = footer;
 
   return (
     <footer
@@ -166,28 +174,8 @@ function Footer(): JSX.Element | null {
           ))}
         {(logo || copyright) && (
           <div className="footer__bottom text--center">
-            {logo && (logo.src || logo.srcDark) && (
-              <div className="margin-bottom--sm">
-                {logo.href ? (
-                  <Link href={logo.href} className={styles.footerLogoLink}>
-                    <FooterLogo
-                      alt={logo.alt}
-                      sources={sources}
-                      width={logo.width}
-                      height={logo.height}
-                    />
-                  </Link>
-                ) : (
-                  <FooterLogo
-                    alt={logo.alt}
-                    sources={sources}
-                    width={logo.width}
-                    height={logo.height}
-                  />
-                )}
-              </div>
-            )}
-            {copyright ? (
+            <FooterLogo logo={logo} />
+            {copyright && (
               <div
                 className="footer__copyright"
                 // Developer provided the HTML, so assume it's safe.
@@ -196,7 +184,7 @@ function Footer(): JSX.Element | null {
                   __html: copyright,
                 }}
               />
-            ) : null}
+            )}
           </div>
         )}
       </div>
diff --git a/packages/docusaurus-theme-classic/src/theme/ThemedImage/index.tsx b/packages/docusaurus-theme-classic/src/theme/ThemedImage/index.tsx
index edf7b3c1b3..66e2a1470a 100644
--- a/packages/docusaurus-theme-classic/src/theme/ThemedImage/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/ThemedImage/index.tsx
@@ -17,7 +17,7 @@ import styles from './styles.module.css';
 export default function ThemedImage(props: Props): JSX.Element {
   const isBrowser = useIsBrowser();
   const {isDarkTheme} = useColorMode();
-  const {sources, className, alt = '', ...propsRest} = props;
+  const {sources, className, alt, ...propsRest} = props;
 
   type SourceName = keyof Props['sources'];
 
diff --git a/packages/docusaurus-theme-classic/src/validateThemeConfig.ts b/packages/docusaurus-theme-classic/src/validateThemeConfig.ts
index f0e7d7bf4a..cd068655bf 100644
--- a/packages/docusaurus-theme-classic/src/validateThemeConfig.ts
+++ b/packages/docusaurus-theme-classic/src/validateThemeConfig.ts
@@ -304,7 +304,7 @@ export const ThemeConfigSchema = Joi.object({
     style: Joi.string().equal('dark', 'light').default('light'),
     logo: Joi.object({
       alt: Joi.string().allow(''),
-      src: Joi.string(),
+      src: Joi.string().required(),
       srcDark: Joi.string(),
       // TODO infer this from reading the image
       width: Joi.alternatives().try(Joi.string(), Joi.number()),
diff --git a/packages/docusaurus-theme-common/src/utils/useThemeConfig.ts b/packages/docusaurus-theme-common/src/utils/useThemeConfig.ts
index 762ed3a149..3c64ef2380 100644
--- a/packages/docusaurus-theme-common/src/utils/useThemeConfig.ts
+++ b/packages/docusaurus-theme-common/src/utils/useThemeConfig.ts
@@ -56,7 +56,7 @@ export type PrismConfig = {
   theme?: PrismTheme;
   darkTheme?: PrismTheme;
   defaultLanguage?: string;
-  additionalLanguages?: string[];
+  additionalLanguages: string[];
 };
 
 export type FooterLinkItem = {
@@ -71,7 +71,7 @@ export type FooterBase = {
   style: 'light' | 'dark';
   logo?: {
     alt?: string;
-    src?: string;
+    src: string;
     srcDark?: string;
     width?: string | number;
     height?: string | number;
diff --git a/packages/docusaurus-types/src/index.d.ts b/packages/docusaurus-types/src/index.d.ts
index d9047970a4..d59184c98b 100644
--- a/packages/docusaurus-types/src/index.d.ts
+++ b/packages/docusaurus-types/src/index.d.ts
@@ -40,24 +40,24 @@ export interface DocusaurusConfig {
   deploymentBranch?: string;
   githubHost?: string;
   githubPort?: string;
-  plugins?: PluginConfig[];
-  themes?: PluginConfig[];
-  presets?: PresetConfig[];
+  plugins: PluginConfig[];
+  themes: PluginConfig[];
+  presets: PresetConfig[];
   themeConfig: ThemeConfig;
   customFields?: {
     [key: string]: unknown;
   };
-  scripts?: (
+  scripts: (
     | string
     | {
         src: string;
         [key: string]: unknown;
       }
   )[];
-  clientModules?: string[];
+  clientModules: string[];
   ssrTemplate?: string;
   staticDirectories: string[];
-  stylesheets?: (
+  stylesheets: (
     | string
     | {
         href: string;
diff --git a/packages/docusaurus/src/client/exports/BrowserOnly.tsx b/packages/docusaurus/src/client/exports/BrowserOnly.tsx
index 28c7bab50d..025049b782 100644
--- a/packages/docusaurus/src/client/exports/BrowserOnly.tsx
+++ b/packages/docusaurus/src/client/exports/BrowserOnly.tsx
@@ -30,5 +30,5 @@ Current type: ${isValidElement(children) ? 'React element' : typeof children}`);
     return <>{children()}</>;
   }
 
-  return fallback || null;
+  return fallback ?? null;
 }
diff --git a/packages/docusaurus/src/client/exports/Link.tsx b/packages/docusaurus/src/client/exports/Link.tsx
index dcbc77635b..6850f23761 100644
--- a/packages/docusaurus/src/client/exports/Link.tsx
+++ b/packages/docusaurus/src/client/exports/Link.tsx
@@ -179,7 +179,7 @@ function Link(
       {...props}
       onMouseEnter={onMouseEnter}
       innerRef={handleRef}
-      to={targetLink || ''}
+      to={targetLink}
       // avoid "React does not recognize the `activeClassName` prop on a DOM
       // element"
       {...(isNavLink && {isActive, activeClassName})}
diff --git a/packages/docusaurus/src/client/serverEntry.tsx b/packages/docusaurus/src/client/serverEntry.tsx
index 8fda0bcd75..f35df05ca5 100644
--- a/packages/docusaurus/src/client/serverEntry.tsx
+++ b/packages/docusaurus/src/client/serverEntry.tsx
@@ -116,14 +116,14 @@ async function doRender(locals: Locals & {path: string}) {
   // manifest information.
   const modulesToBeLoaded = [...manifest.entrypoints, ...Array.from(modules)];
   const bundles = getBundles(manifest, modulesToBeLoaded);
-  const stylesheets = (bundles.css || []).map((b) => b.file);
-  const scripts = (bundles.js || []).map((b) => b.file);
+  const stylesheets = (bundles.css ?? []).map((b) => b.file);
+  const scripts = (bundles.js ?? []).map((b) => b.file);
 
   const renderedHtml = renderSSRTemplate(ssrTemplate, {
     appHtml,
     baseUrl,
-    htmlAttributes: htmlAttributes || '',
-    bodyAttributes: bodyAttributes || '',
+    htmlAttributes,
+    bodyAttributes,
     headTags,
     preBodyTags,
     postBodyTags,
diff --git a/packages/docusaurus/src/commands/commandUtils.ts b/packages/docusaurus/src/commands/commandUtils.ts
index 17f661982f..cfa5f7e920 100644
--- a/packages/docusaurus/src/commands/commandUtils.ts
+++ b/packages/docusaurus/src/commands/commandUtils.ts
@@ -12,7 +12,7 @@ import {DEFAULT_PORT} from '@docusaurus/utils';
 export function getCLIOptionHost(
   hostOption: HostPortCLIOptions['host'],
 ): string {
-  return hostOption || 'localhost';
+  return hostOption ?? 'localhost';
 }
 
 export async function getCLIOptionPort(
diff --git a/packages/docusaurus/src/commands/start.ts b/packages/docusaurus/src/commands/start.ts
index 64b753227c..b1d469faa8 100644
--- a/packages/docusaurus/src/commands/start.ts
+++ b/packages/docusaurus/src/commands/start.ts
@@ -75,7 +75,7 @@ export default async function start(
         logger.error(err.stack);
       });
   }, 500);
-  const {siteConfig, plugins = []} = props;
+  const {siteConfig, plugins} = props;
 
   const normalizeToSiteDir = (filepath: string) => {
     if (filepath && path.isAbsolute(filepath)) {
@@ -84,12 +84,9 @@ export default async function start(
     return posixPath(filepath);
   };
 
-  const pluginPaths = ([] as string[])
-    .concat(
-      ...plugins
-        .map((plugin) => plugin.getPathsToWatch?.() ?? [])
-        .filter(Boolean),
-    )
+  const pluginPaths = plugins
+    .flatMap((plugin) => plugin.getPathsToWatch?.() ?? [])
+    .filter(Boolean)
     .map(normalizeToSiteDir);
 
   const pathsToWatch = [
diff --git a/packages/docusaurus/src/server/__tests__/__snapshots__/config.test.ts.snap b/packages/docusaurus/src/server/__tests__/__snapshots__/config.test.ts.snap
index 5256204af0..ac70cb4e3f 100644
--- a/packages/docusaurus/src/server/__tests__/__snapshots__/config.test.ts.snap
+++ b/packages/docusaurus/src/server/__tests__/__snapshots__/config.test.ts.snap
@@ -15,6 +15,7 @@ exports[`loadConfig website with valid async config 1`] = `
 Object {
   "baseUrl": "/",
   "baseUrlIssueBanner": true,
+  "clientModules": Array [],
   "customFields": Object {},
   "i18n": Object {
     "defaultLocale": "en",
@@ -31,9 +32,11 @@ Object {
   "plugins": Array [],
   "presets": Array [],
   "projectName": "hello",
+  "scripts": Array [],
   "staticDirectories": Array [
     "static",
   ],
+  "stylesheets": Array [],
   "tagline": "Hello World",
   "themeConfig": Object {},
   "themes": Array [],
@@ -47,6 +50,7 @@ exports[`loadConfig website with valid async config creator function 1`] = `
 Object {
   "baseUrl": "/",
   "baseUrlIssueBanner": true,
+  "clientModules": Array [],
   "customFields": Object {},
   "i18n": Object {
     "defaultLocale": "en",
@@ -63,9 +67,11 @@ Object {
   "plugins": Array [],
   "presets": Array [],
   "projectName": "hello",
+  "scripts": Array [],
   "staticDirectories": Array [
     "static",
   ],
+  "stylesheets": Array [],
   "tagline": "Hello World",
   "themeConfig": Object {},
   "themes": Array [],
@@ -79,6 +85,7 @@ exports[`loadConfig website with valid config creator function 1`] = `
 Object {
   "baseUrl": "/",
   "baseUrlIssueBanner": true,
+  "clientModules": Array [],
   "customFields": Object {},
   "i18n": Object {
     "defaultLocale": "en",
@@ -95,9 +102,11 @@ Object {
   "plugins": Array [],
   "presets": Array [],
   "projectName": "hello",
+  "scripts": Array [],
   "staticDirectories": Array [
     "static",
   ],
+  "stylesheets": Array [],
   "tagline": "Hello World",
   "themeConfig": Object {},
   "themes": Array [],
@@ -111,6 +120,7 @@ exports[`loadConfig website with valid siteConfig 1`] = `
 Object {
   "baseUrl": "/",
   "baseUrlIssueBanner": true,
+  "clientModules": Array [],
   "customFields": Object {},
   "favicon": "img/docusaurus.ico",
   "i18n": Object {
@@ -136,9 +146,11 @@ Object {
   ],
   "presets": Array [],
   "projectName": "hello",
+  "scripts": Array [],
   "staticDirectories": Array [
     "static",
   ],
+  "stylesheets": Array [],
   "tagline": "Hello World",
   "themeConfig": Object {},
   "themes": Array [],
diff --git a/packages/docusaurus/src/server/configValidation.ts b/packages/docusaurus/src/server/configValidation.ts
index 78dee2de68..241a6cbe0a 100644
--- a/packages/docusaurus/src/server/configValidation.ts
+++ b/packages/docusaurus/src/server/configValidation.ts
@@ -26,6 +26,9 @@ export const DEFAULT_CONFIG: Pick<
   | 'plugins'
   | 'themes'
   | 'presets'
+  | 'stylesheets'
+  | 'scripts'
+  | 'clientModules'
   | 'customFields'
   | 'themeConfig'
   | 'titleDelimiter'
@@ -41,6 +44,9 @@ export const DEFAULT_CONFIG: Pick<
   plugins: [],
   themes: [],
   presets: [],
+  stylesheets: [],
+  scripts: [],
+  clientModules: [],
   customFields: {},
   themeConfig: {},
   titleDelimiter: '|',
@@ -170,25 +176,31 @@ export const ConfigSchema = Joi.object({
   themes: Joi.array().items(ThemeSchema).default(DEFAULT_CONFIG.themes),
   presets: Joi.array().items(PresetSchema).default(DEFAULT_CONFIG.presets),
   themeConfig: Joi.object().unknown().default(DEFAULT_CONFIG.themeConfig),
-  scripts: Joi.array().items(
-    Joi.string(),
-    Joi.object({
-      src: Joi.string().required(),
-      async: Joi.bool(),
-      defer: Joi.bool(),
-    })
-      // See https://github.com/facebook/docusaurus/issues/3378
-      .unknown(),
-  ),
+  scripts: Joi.array()
+    .items(
+      Joi.string(),
+      Joi.object({
+        src: Joi.string().required(),
+        async: Joi.bool(),
+        defer: Joi.bool(),
+      })
+        // See https://github.com/facebook/docusaurus/issues/3378
+        .unknown(),
+    )
+    .default(DEFAULT_CONFIG.scripts),
   ssrTemplate: Joi.string(),
-  stylesheets: Joi.array().items(
-    Joi.string(),
-    Joi.object({
-      href: Joi.string().required(),
-      type: Joi.string(),
-    }).unknown(),
-  ),
-  clientModules: Joi.array().items(Joi.string()),
+  stylesheets: Joi.array()
+    .items(
+      Joi.string(),
+      Joi.object({
+        href: Joi.string().required(),
+        type: Joi.string(),
+      }).unknown(),
+    )
+    .default(DEFAULT_CONFIG.stylesheets),
+  clientModules: Joi.array()
+    .items(Joi.string())
+    .default(DEFAULT_CONFIG.clientModules),
   tagline: Joi.string().allow('').default(DEFAULT_CONFIG.tagline),
   titleDelimiter: Joi.string().default('|'),
   noIndex: Joi.bool().default(false),
diff --git a/packages/docusaurus/src/server/html-tags/htmlTags.ts b/packages/docusaurus/src/server/html-tags/htmlTags.ts
index d14dace0a5..83946c1978 100644
--- a/packages/docusaurus/src/server/html-tags/htmlTags.ts
+++ b/packages/docusaurus/src/server/html-tags/htmlTags.ts
@@ -33,7 +33,7 @@ export default function htmlTagObjectToString(tagDefinition: unknown): string {
     );
   }
   const isVoidTag = voidHtmlTags.indexOf(tagDefinition.tagName) !== -1;
-  const tagAttributes = tagDefinition.attributes || {};
+  const tagAttributes = tagDefinition.attributes ?? {};
   const attributes = Object.keys(tagAttributes)
     .filter((attributeName) => tagAttributes[attributeName] !== false)
     .map((attributeName) => {
diff --git a/packages/docusaurus/src/server/html-tags/index.ts b/packages/docusaurus/src/server/html-tags/index.ts
index 8837b0f5ba..d18ca99af6 100644
--- a/packages/docusaurus/src/server/html-tags/index.ts
+++ b/packages/docusaurus/src/server/html-tags/index.ts
@@ -28,7 +28,7 @@ export function loadHtmlTags(plugins: LoadedPlugin[]): InjectedHtmlTags {
         return acc;
       }
       const {headTags, preBodyTags, postBodyTags} =
-        plugin.injectHtmlTags({content: plugin.content}) || {};
+        plugin.injectHtmlTags({content: plugin.content}) ?? {};
       return {
         headTags: headTags
           ? `${acc.headTags}\n${createHtmlTagsString(headTags)}`
diff --git a/packages/docusaurus/src/server/index.ts b/packages/docusaurus/src/server/index.ts
index 6a943a487e..414125b416 100644
--- a/packages/docusaurus/src/server/index.ts
+++ b/packages/docusaurus/src/server/index.ts
@@ -160,10 +160,10 @@ export async function loadPluginConfigs(
   presetThemes = presetThemes.map((theme) =>
     normalizeShorthand(theme, 'theme'),
   );
-  const standalonePlugins = (siteConfig.plugins || []).map((plugin) =>
+  const standalonePlugins = siteConfig.plugins.map((plugin) =>
     normalizeShorthand(plugin, 'plugin'),
   );
-  const standaloneThemes = (siteConfig.themes || []).map((theme) =>
+  const standaloneThemes = siteConfig.themes.map((theme) =>
     normalizeShorthand(theme, 'theme'),
   );
   return [
@@ -184,9 +184,9 @@ function createBootstrapPlugin({
   siteConfig: DocusaurusConfig;
 }): LoadedPlugin {
   const {
-    stylesheets = [],
-    scripts = [],
-    clientModules: siteConfigClientModules = [],
+    stylesheets,
+    scripts,
+    clientModules: siteConfigClientModules,
   } = siteConfig;
   return {
     name: 'docusaurus-bootstrap-plugin',
@@ -314,6 +314,7 @@ export async function load(
     generatedFilesDir,
     'DONT-EDIT-THIS-FOLDER',
     `This folder stores temp files that Docusaurus' client bundler accesses.
+
 DO NOT hand-modify files in this folder because they will be overwritten in the
 next build. You can clear all build artifacts (including this folder) with the
 \`docusaurus clear\` command.
@@ -326,11 +327,12 @@ next build. You can clear all build artifacts (including this folder) with the
     generatedFilesDir,
     DEFAULT_CONFIG_FILE_NAME,
     `/*
-AUTOGENERATED - DON'T EDIT
-Your edits in this file will be overwritten in the next build!
-Modify the docusaurus.config.js file at your site's root instead.
-*/
-export default ${JSON.stringify(siteConfig, null, 2)};`,
+ * AUTOGENERATED - DON'T EDIT
+ * Your edits in this file will be overwritten in the next build!
+ * Modify the docusaurus.config.js file at your site's root instead.
+ */
+export default ${JSON.stringify(siteConfig, null, 2)};
+`,
   );
 
   plugins.push(createBootstrapPlugin({siteConfig}));
@@ -341,11 +343,14 @@ export default ${JSON.stringify(siteConfig, null, 2)};`,
   const genClientModules = generate(
     generatedFilesDir,
     'client-modules.js',
-    `export default [\n${clientModules
-      // import() is async so we use require() because client modules can have
-      // CSS and the order matters for loading CSS.
-      .map((module) => `  require('${escapePath(module)}'),`)
-      .join('\n')}\n];\n`,
+    `export default [
+${clientModules
+  // import() is async so we use require() because client modules can have
+  // CSS and the order matters for loading CSS.
+  .map((module) => `  require('${escapePath(module)}'),`)
+  .join('\n')}
+];
+`,
   );
 
   // Load extra head & body html tags.
@@ -367,7 +372,8 @@ ${Object.entries(registry)
         chunk.modulePath,
       )}', require.resolveWeak('${escapePath(chunk.modulePath)}')],`,
   )
-  .join('\n')}};\n`,
+  .join('\n')}};
+`,
   );
 
   const genRoutesChunkNames = generate(
diff --git a/packages/docusaurus/src/server/presets/__tests__/index.test.ts b/packages/docusaurus/src/server/presets/__tests__/index.test.ts
index cc5501874f..5066901d1f 100644
--- a/packages/docusaurus/src/server/presets/__tests__/index.test.ts
+++ b/packages/docusaurus/src/server/presets/__tests__/index.test.ts
@@ -14,7 +14,9 @@ describe('loadPresets', () => {
   test('no presets', async () => {
     const context = {
       siteConfigPath: __dirname,
-      siteConfig: {},
+      siteConfig: {
+        presets: [],
+      },
     } as LoadContext;
     const presets = await loadPresets(context);
     expect(presets).toMatchInlineSnapshot(`
diff --git a/packages/docusaurus/src/server/presets/index.ts b/packages/docusaurus/src/server/presets/index.ts
index 235493e044..23c0a1025f 100644
--- a/packages/docusaurus/src/server/presets/index.ts
+++ b/packages/docusaurus/src/server/presets/index.ts
@@ -10,7 +10,6 @@ import importFresh from 'import-fresh';
 import type {
   LoadContext,
   PluginConfig,
-  PresetConfig,
   ImportedPresetModule,
 } from '@docusaurus/types';
 import {resolveModuleName} from '../moduleShorthand';
@@ -23,7 +22,7 @@ export default async function loadPresets(context: LoadContext): Promise<{
   // siteDir's package.json declares the dependency on these presets.
   const presetRequire = createRequire(context.siteConfigPath);
 
-  const presets: PresetConfig[] = context.siteConfig.presets || [];
+  const {presets} = context.siteConfig;
   const unflatPlugins: PluginConfig[][] = [];
   const unflatThemes: PluginConfig[][] = [];
 
diff --git a/packages/docusaurus/src/webpack/plugins/CleanWebpackPlugin.ts b/packages/docusaurus/src/webpack/plugins/CleanWebpackPlugin.ts
index 62911f77e3..e6bae7173d 100644
--- a/packages/docusaurus/src/webpack/plugins/CleanWebpackPlugin.ts
+++ b/packages/docusaurus/src/webpack/plugins/CleanWebpackPlugin.ts
@@ -176,7 +176,7 @@ export default class CleanWebpackPlugin {
       stats.toJson({
         all: false,
         assets: true,
-      }).assets || [];
+      }).assets ?? [];
     const assets = statsAssets.map((asset: {name: string}) => asset.name);
 
     /**
diff --git a/packages/lqip-loader/src/index.ts b/packages/lqip-loader/src/index.ts
index 7bd0b4d08a..b491949dff 100644
--- a/packages/lqip-loader/src/index.ts
+++ b/packages/lqip-loader/src/index.ts
@@ -23,7 +23,7 @@ export default async function lqipLoader(
   const callback = this.async();
   const imgPath = this.resourcePath;
 
-  const config = this.getOptions() || {};
+  const config = this.getOptions() ?? {};
   config.base64 = 'base64' in config ? config.base64 : true;
   // color palette generation is set to false by default
   // since it is little bit slower than base64 generation