From 4db0c620de4af0412167d080c833de70c53ee800 Mon Sep 17 00:00:00 2001
From: Joshua Chen <sidachen2003@gmail.com>
Date: Sun, 6 Mar 2022 13:09:10 +0800
Subject: [PATCH] refactor: enable a few TS flags (#6852)

* refactor: enable a few TS flags

* refactor

* revert to working version

* fix

* better

* change
---
 packages/docusaurus-logger/src/index.ts       |  4 +-
 .../src/remark/toc/index.ts                   |  2 +-
 .../docusaurus-migrate/src/frontMatter.ts     |  6 +--
 packages/docusaurus-migrate/src/index.ts      |  4 +-
 packages/docusaurus-migrate/src/transform.ts  |  8 ++-
 .../src/blogUtils.ts                          |  8 +--
 .../src/index.ts                              |  4 +-
 .../src/translations.ts                       | 13 +++--
 .../src/docs.ts                               |  2 +-
 .../src/sidebars/index.ts                     |  2 +-
 .../src/sidebars/utils.ts                     |  8 +--
 .../src/translations.ts                       |  8 ++-
 .../src/versions.ts                           |  4 +-
 .../src/index.ts                              |  2 +-
 .../docusaurus-theme-classic/src/index.ts     |  2 +-
 .../src/theme/BackToTopButton/index.tsx       |  2 +-
 .../src/theme/BlogPostItem/index.tsx          |  2 +-
 .../src/theme/CodeBlock/index.tsx             |  4 +-
 .../src/theme/ColorModeToggle/index.tsx       |  6 +--
 .../src/theme/DocItem/index.tsx               |  2 +-
 .../src/theme/DocPage/index.tsx               | 10 ++--
 .../src/theme/DocSidebar/index.tsx            |  6 +--
 .../src/theme/Footer/index.tsx                |  2 +-
 .../src/theme/Heading/index.tsx               |  4 +-
 .../src/theme/LayoutHead/index.tsx            |  2 +-
 .../src/theme/Navbar/index.tsx                |  4 +-
 .../LocaleDropdownNavbarItem/index.tsx        |  2 +-
 .../src/theme/TOCCollapsible/index.tsx        |  2 +-
 .../src/theme/Tabs/index.tsx                  |  8 +--
 .../src/theme/Tag/index.tsx                   |  4 +-
 .../src/translations.ts                       | 16 ++++--
 .../docusaurus-theme-classic/tsconfig.json    |  2 +-
 .../src/components/Details/index.tsx          |  2 +-
 .../src/utils/codeBlockUtils.ts               |  4 +-
 .../DocsPreferredVersionProvider.tsx          |  2 +-
 .../useDocsPreferredVersion.ts                |  6 +--
 .../src/utils/tagsUtils.ts                    |  6 +--
 .../src/utils/tocUtils.ts                     |  2 +-
 .../src/utils/useContextualSearchFilters.ts   |  4 +-
 .../src/utils/usePluralForm.ts                |  4 +-
 .../src/utils/useTOCHighlight.ts              |  2 +-
 .../src/theme/SearchPage/index.tsx            |  4 +-
 .../src/applyTrailingSlash.ts                 |  2 +-
 packages/docusaurus-utils/src/constants.ts    |  4 +-
 .../docusaurus-utils/src/markdownLinks.ts     |  7 +--
 .../docusaurus-utils/src/markdownParser.ts    | 11 ++--
 packages/docusaurus-utils/src/tags.ts         |  4 +-
 packages/docusaurus-utils/src/urlUtils.ts     | 11 +++-
 packages/docusaurus/src/choosePort.ts         |  2 +-
 .../src/client/PendingNavigation.tsx          |  4 +-
 .../src/client/exports/ComponentCreator.tsx   | 16 +++---
 .../src/client/exports/ErrorBoundary.tsx      |  4 +-
 .../src/client/exports/Translate.tsx          |  2 +-
 packages/docusaurus/src/client/flat.ts        |  3 +-
 packages/docusaurus/src/client/prefetch.ts    |  6 +--
 .../docusaurus/src/client/serverEntry.tsx     |  2 +-
 .../src/client/theme-fallback/Root/index.tsx  |  6 +--
 packages/docusaurus/src/commands/build.ts     |  4 +-
 .../src/commands/swizzle/context.ts           |  2 +-
 packages/docusaurus/src/server/brokenLinks.ts |  2 +-
 packages/docusaurus/src/server/index.ts       | 12 ++---
 .../docusaurus/src/server/plugins/index.ts    |  4 +-
 packages/docusaurus/src/server/routes.ts      |  4 +-
 .../docusaurus/src/server/themes/index.ts     |  6 +--
 .../translations/translationsExtractor.ts     |  2 +-
 .../src/webpack/plugins/ChunkAssetPlugin.ts   | 11 ++--
 .../src/webpack/plugins/LogPlugin.ts          |  2 +-
 packages/docusaurus/tsconfig.json             |  1 -
 packages/lqip-loader/src/index.ts             |  4 +-
 packages/lqip-loader/src/lqip.ts              |  5 +-
 tsconfig.json                                 | 50 +++++++++++--------
 71 files changed, 210 insertions(+), 174 deletions(-)

diff --git a/packages/docusaurus-logger/src/index.ts b/packages/docusaurus-logger/src/index.ts
index 6937ddde6d..041d1d04b4 100644
--- a/packages/docusaurus-logger/src/index.ts
+++ b/packages/docusaurus-logger/src/index.ts
@@ -21,8 +21,8 @@ function interpolate(
 ): string {
   let res = '';
   values.forEach((value, idx) => {
-    const flag = msgs[idx].match(/[a-z]+=$/);
-    res += msgs[idx].replace(/[a-z]+=$/, '');
+    const flag = msgs[idx]!.match(/[a-z]+=$/);
+    res += msgs[idx]!.replace(/[a-z]+=$/, '');
     const format = (() => {
       if (!flag) {
         return (a: string | number) => a;
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/index.ts b/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
index 34657e633f..0e25a5a462 100644
--- a/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
@@ -94,7 +94,7 @@ export default function plugin(options: PluginOptions = {}): Transformer {
     const targetIndex = getOrCreateExistingTargetIndex(children, name);
 
     if (headings && headings.length) {
-      children[targetIndex].value = `export const ${name} = ${stringifyObject(
+      children[targetIndex]!.value = `export const ${name} = ${stringifyObject(
         headings,
       )};`;
     }
diff --git a/packages/docusaurus-migrate/src/frontMatter.ts b/packages/docusaurus-migrate/src/frontMatter.ts
index 45e71c94a2..4905863cf5 100644
--- a/packages/docusaurus-migrate/src/frontMatter.ts
+++ b/packages/docusaurus-migrate/src/frontMatter.ts
@@ -37,8 +37,8 @@ export default function extractMetadata(content: string): Data {
 
   // New line characters => to handle all operating systems.
   const lines = (both.header ?? '').split(/\r?\n/);
-  for (let i = 0; i < lines.length - 1; i += 1) {
-    const keyValue = lines[i].split(':');
+  lines.slice(0, -1).forEach((line) => {
+    const keyValue = line.split(':') as [string, ...string[]];
     const key = keyValue[0].trim();
     let value = keyValue.slice(1).join(':').trim();
     try {
@@ -47,7 +47,7 @@ export default function extractMetadata(content: string): Data {
       // Ignore the error as it means it's not a JSON value.
     }
     metadata[key] = value;
-  }
+  });
   return {metadata, rawContent: both.content};
 }
 
diff --git a/packages/docusaurus-migrate/src/index.ts b/packages/docusaurus-migrate/src/index.ts
index 4d1884038e..b7480640b3 100644
--- a/packages/docusaurus-migrate/src/index.ts
+++ b/packages/docusaurus-migrate/src/index.ts
@@ -535,7 +535,7 @@ async function migrateVersionedSidebar(
     // Order matters: if a sidebar file doesn't exist, we have to use the
     // previous version's
     for (let i = 0; i < versions.length; i += 1) {
-      const version = versions[i];
+      const version = versions[i]!;
       let sidebarEntries: SidebarEntries;
       const sidebarPath = path.join(
         siteDir,
@@ -545,7 +545,7 @@ async function migrateVersionedSidebar(
       try {
         sidebarEntries = JSON.parse(await fs.readFile(sidebarPath, 'utf-8'));
       } catch {
-        sidebars.push({version, entries: sidebars[i - 1].entries});
+        sidebars.push({version, entries: sidebars[i - 1]!.entries});
         return;
       }
       const newSidebar = Object.entries(sidebarEntries).reduce(
diff --git a/packages/docusaurus-migrate/src/transform.ts b/packages/docusaurus-migrate/src/transform.ts
index c83bb229fd..24820cf7e9 100644
--- a/packages/docusaurus-migrate/src/transform.ts
+++ b/packages/docusaurus-migrate/src/transform.ts
@@ -33,6 +33,9 @@ const property = (key: string, value: ArrowFunctionExpression) =>
 
 const processCallExpression = (node: ASTPath<VariableDeclarator>) => {
   const args = (node?.value?.init as CallExpression)?.arguments[0];
+  if (!args) {
+    return;
+  }
   if (args.type === 'Literal') {
     if (
       typeof args.value === 'string' &&
@@ -71,6 +74,9 @@ const processMemberExpression = (node: ASTPath<VariableDeclarator>) => {
     return;
   }
   const args = object.arguments[0];
+  if (!args) {
+    return;
+  }
   if (args.type === 'Literal') {
     if (args.value === '../../core/CompLibrary.js') {
       const newDeclarator = jscodeshift.variableDeclarator(
@@ -117,7 +123,7 @@ export default function transformer(file: string): string {
     }
   });
   if (r[r.length - 1]) {
-    jscodeshift(r[r.length - 1].parent).insertAfter(
+    jscodeshift(r[r.length - 1]!.parent).insertAfter(
       jscodeshift.importDeclaration(
         [jscodeshift.importDefaultSpecifier(jscodeshift.identifier('Layout'))],
         jscodeshift.literal('@theme/Layout'),
diff --git a/packages/docusaurus-plugin-content-blog/src/blogUtils.ts b/packages/docusaurus-plugin-content-blog/src/blogUtils.ts
index 6ae982b7b2..39d0b70b7b 100644
--- a/packages/docusaurus-plugin-content-blog/src/blogUtils.ts
+++ b/packages/docusaurus-plugin-content-blog/src/blogUtils.ts
@@ -139,10 +139,10 @@ export function parseBlogFileName(
   if (dateFilenameMatch) {
     const {folder, text, date: dateString} = dateFilenameMatch.groups!;
     // Always treat dates as UTC by adding the `Z`
-    const date = new Date(`${dateString}Z`);
-    const slugDate = dateString.replace(/-/g, '/');
-    const slug = `/${slugDate}/${folder}${text}`;
-    return {date, text, slug};
+    const date = new Date(`${dateString!}Z`);
+    const slugDate = dateString!.replace(/-/g, '/');
+    const slug = `/${slugDate}/${folder!}${text!}`;
+    return {date, text: text!, slug};
   }
   const text = blogSourceRelative.replace(/(?:\/index)?\.mdx?$/, '');
   const slug = `/${text}`;
diff --git a/packages/docusaurus-plugin-content-blog/src/index.ts b/packages/docusaurus-plugin-content-blog/src/index.ts
index a49529224a..a1f92f23e9 100644
--- a/packages/docusaurus-plugin-content-blog/src/index.ts
+++ b/packages/docusaurus-plugin-content-blog/src/index.ts
@@ -307,7 +307,7 @@ export default async function pluginContentBlog(
                 ({
                   content: {
                     __import: true,
-                    path: blogItemsToMetadata[postID].source,
+                    path: blogItemsToMetadata[postID]!.source,
                     query: {
                       truncated: true,
                     },
@@ -359,7 +359,7 @@ export default async function pluginContentBlog(
               modules: {
                 sidebar: aliasedSource(sidebarProp),
                 items: items.map((postID) => {
-                  const blogPostMetadata = blogItemsToMetadata[postID];
+                  const blogPostMetadata = blogItemsToMetadata[postID]!;
                   return {
                     content: {
                       __import: true,
diff --git a/packages/docusaurus-plugin-content-blog/src/translations.ts b/packages/docusaurus-plugin-content-blog/src/translations.ts
index 09598e59ab..6459fec598 100644
--- a/packages/docusaurus-plugin-content-blog/src/translations.ts
+++ b/packages/docusaurus-plugin-content-blog/src/translations.ts
@@ -19,8 +19,9 @@ function translateListPage(
       items,
       metadata: {
         ...metadata,
-        blogTitle: translations.title.message,
-        blogDescription: translations.description.message,
+        blogTitle: translations.title?.message ?? page.metadata.blogTitle,
+        blogDescription:
+          translations.description?.message ?? page.metadata.blogDescription,
       },
     };
   });
@@ -52,10 +53,14 @@ export function translateContent(
   content: BlogContent,
   translationFiles: TranslationFiles,
 ): BlogContent {
-  const [{content: optionsTranslations}] = translationFiles;
+  if (translationFiles.length === 0) {
+    return content;
+  }
+  const {content: optionsTranslations} = translationFiles[0]!;
   return {
     ...content,
-    blogSidebarTitle: optionsTranslations['sidebar.title'].message,
+    blogSidebarTitle:
+      optionsTranslations['sidebar.title']?.message ?? content.blogSidebarTitle,
     blogListPaginated: translateListPage(
       content.blogListPaginated,
       optionsTranslations,
diff --git a/packages/docusaurus-plugin-content-docs/src/docs.ts b/packages/docusaurus-plugin-content-docs/src/docs.ts
index 5e89dd53d8..b58c4c2353 100644
--- a/packages/docusaurus-plugin-content-docs/src/docs.ts
+++ b/packages/docusaurus-plugin-content-docs/src/docs.ts
@@ -363,7 +363,7 @@ export function getMainDocId({
           doc.unversionedId === firstDocIdOfFirstSidebar,
       )!;
     }
-    return docs[0];
+    return docs[0]!;
   }
 
   return getMainDoc().unversionedId;
diff --git a/packages/docusaurus-plugin-content-docs/src/sidebars/index.ts b/packages/docusaurus-plugin-content-docs/src/sidebars/index.ts
index 801a86dafd..547a7bd567 100644
--- a/packages/docusaurus-plugin-content-docs/src/sidebars/index.ts
+++ b/packages/docusaurus-plugin-content-docs/src/sidebars/index.ts
@@ -49,7 +49,7 @@ async function readCategoriesMetadata(contentPath: string) {
   const categoryToFile = _.groupBy(categoryFiles, path.dirname);
   return combinePromises(
     _.mapValues(categoryToFile, async (files, folder) => {
-      const [filePath] = files;
+      const filePath = files[0]!;
       if (files.length > 1) {
         logger.warn`There are more than one category metadata files for path=${folder}: ${files.join(
           ', ',
diff --git a/packages/docusaurus-plugin-content-docs/src/sidebars/utils.ts b/packages/docusaurus-plugin-content-docs/src/sidebars/utils.ts
index a0c69020eb..1da2c7aee0 100644
--- a/packages/docusaurus-plugin-content-docs/src/sidebars/utils.ts
+++ b/packages/docusaurus-plugin-content-docs/src/sidebars/utils.ts
@@ -201,12 +201,12 @@ export function createSidebarsUtils(sidebars: Sidebars): SidebarsUtils {
     if (!sidebarName) {
       return emptySidebarNavigation();
     }
-    if (!sidebarNameToNavigationItems[sidebarName]) {
+    const navigationItems = sidebarNameToNavigationItems[sidebarName];
+    if (!navigationItems) {
       throw new Error(
         `Doc with ID ${docId} wants to display sidebar ${sidebarName} but a sidebar with this name doesn't exist`,
       );
     }
-    const navigationItems = sidebarNameToNavigationItems[sidebarName];
     const currentItemIndex = navigationItems.findIndex((item) => {
       if (item.type === 'doc') {
         return item.id === docId;
@@ -263,7 +263,7 @@ export function createSidebarsUtils(sidebars: Sidebars): SidebarsUtils {
     if (!sidebarName) {
       return emptySidebarNavigation();
     }
-    const navigationItems = sidebarNameToNavigationItems[sidebarName];
+    const navigationItems = sidebarNameToNavigationItems[sidebarName]!;
     const currentItemIndex = navigationItems.findIndex(
       isCurrentCategoryGeneratedIndexItem,
     );
@@ -341,7 +341,7 @@ Available document ids are:
     getCategoryGeneratedIndexList,
     getCategoryGeneratedIndexNavigation,
     checkSidebarsDocIds,
-    getFirstLink: (id) => getFirstLink(sidebars[id]),
+    getFirstLink: (id) => getFirstLink(sidebars[id]!),
   };
 }
 
diff --git a/packages/docusaurus-plugin-content-docs/src/translations.ts b/packages/docusaurus-plugin-content-docs/src/translations.ts
index 47e82cf3a1..49681b01ea 100644
--- a/packages/docusaurus-plugin-content-docs/src/translations.ts
+++ b/packages/docusaurus-plugin-content-docs/src/translations.ts
@@ -274,10 +274,14 @@ function translateVersion(
   translationFiles: Record<string, TranslationFile>,
 ): LoadedVersion {
   const versionTranslations =
-    translationFiles[getVersionFileName(version.versionName)].content;
+    translationFiles[getVersionFileName(version.versionName)]?.content;
+  if (!versionTranslations) {
+    return version;
+  }
   return {
     ...version,
-    versionLabel: versionTranslations['version.label']?.message,
+    versionLabel:
+      versionTranslations['version.label']?.message ?? version.versionLabel,
     sidebars: translateSidebars(version, versionTranslations),
     // docs: translateDocs(version.docs, versionTranslations),
   };
diff --git a/packages/docusaurus-plugin-content-docs/src/versions.ts b/packages/docusaurus-plugin-content-docs/src/versions.ts
index 52d1c476bf..26fd63773c 100644
--- a/packages/docusaurus-plugin-content-docs/src/versions.ts
+++ b/packages/docusaurus-plugin-content-docs/src/versions.ts
@@ -464,11 +464,11 @@ Please set the docs "sidebarPath" field in your config file to:
 // "last version" is not a very good concept nor api surface
 function getDefaultLastVersionName(versionNames: string[]) {
   if (versionNames.length === 1) {
-    return versionNames[0];
+    return versionNames[0]!;
   }
   return versionNames.filter(
     (versionName) => versionName !== CURRENT_VERSION_NAME,
-  )[0];
+  )[0]!;
 }
 
 function checkVersionsOptions(
diff --git a/packages/docusaurus-remark-plugin-npm2yarn/src/index.ts b/packages/docusaurus-remark-plugin-npm2yarn/src/index.ts
index 7f80ed3678..b16949dd72 100644
--- a/packages/docusaurus-remark-plugin-npm2yarn/src/index.ts
+++ b/packages/docusaurus-remark-plugin-npm2yarn/src/index.ts
@@ -71,7 +71,7 @@ const plugin: Plugin<[PluginOptions?]> = (options = {}) => {
       if (isParent(node)) {
         let index = 0;
         while (index < node.children.length) {
-          const child = node.children[index];
+          const child = node.children[index]!;
           if (matchNode(child)) {
             const result = transformNode(child, sync);
             node.children.splice(index, 1, ...result);
diff --git a/packages/docusaurus-theme-classic/src/index.ts b/packages/docusaurus-theme-classic/src/index.ts
index 6bccc8f88e..c401e48ddb 100644
--- a/packages/docusaurus-theme-classic/src/index.ts
+++ b/packages/docusaurus-theme-classic/src/index.ts
@@ -107,7 +107,7 @@ export default function docusaurusThemeClassic(
     prism: {additionalLanguages = []} = {},
   } = themeConfig;
   const {customCss} = options || {};
-  const {direction} = localeConfigs[currentLocale];
+  const {direction} = localeConfigs[currentLocale]!;
 
   return {
     name: 'docusaurus-theme-classic',
diff --git a/packages/docusaurus-theme-classic/src/theme/BackToTopButton/index.tsx b/packages/docusaurus-theme-classic/src/theme/BackToTopButton/index.tsx
index 4c4681c24b..1a3bb4a545 100644
--- a/packages/docusaurus-theme-classic/src/theme/BackToTopButton/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/BackToTopButton/index.tsx
@@ -133,7 +133,7 @@ export default function BackToTopButton(): JSX.Element {
         ThemeClassNames.common.backToTopButton,
         styles.backToTopButton,
         {
-          [styles.backToTopButtonShow]: show,
+          [styles.backToTopButtonShow!]: show,
         },
       )}
       type="button"
diff --git a/packages/docusaurus-theme-classic/src/theme/BlogPostItem/index.tsx b/packages/docusaurus-theme-classic/src/theme/BlogPostItem/index.tsx
index 6004ecf6f6..974cf93ad0 100644
--- a/packages/docusaurus-theme-classic/src/theme/BlogPostItem/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/BlogPostItem/index.tsx
@@ -114,7 +114,7 @@ export default function BlogPostItem(props: Props): JSX.Element {
       {(tagsExists || truncated) && (
         <footer
           className={clsx('row docusaurus-mt-lg', {
-            [styles.blogPostDetailsFull]: isBlogPostPage,
+            [styles.blogPostDetailsFull!]: isBlogPostPage,
           })}>
           {tagsExists && (
             <div className={clsx('col', {'col--9': truncatedPost})}>
diff --git a/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx b/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx
index 2d214b5619..994f325f4c 100644
--- a/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/CodeBlock/index.tsx
@@ -128,8 +128,8 @@ export default function CodeBlock({
               style={style}>
               <code className={styles.codeBlockLines}>
                 {tokens.map((line, i) => {
-                  if (line.length === 1 && line[0].content === '\n') {
-                    line[0].content = '';
+                  if (line.length === 1 && line[0]!.content === '\n') {
+                    line[0]!.content = '';
                   }
 
                   const lineProps = getLineProps({line, key: i});
diff --git a/packages/docusaurus-theme-classic/src/theme/ColorModeToggle/index.tsx b/packages/docusaurus-theme-classic/src/theme/ColorModeToggle/index.tsx
index 46be740f6f..680f9f42d3 100644
--- a/packages/docusaurus-theme-classic/src/theme/ColorModeToggle/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/ColorModeToggle/index.tsx
@@ -32,9 +32,9 @@ function ColorModeToggle({
   return (
     <div
       className={clsx(styles.toggle, className, {
-        [styles.toggleChecked]: checked,
-        [styles.toggleFocused]: focused,
-        [styles.toggleDisabled]: !isBrowser,
+        [styles.toggleChecked!]: checked,
+        [styles.toggleFocused!]: focused,
+        [styles.toggleDisabled!]: !isBrowser,
       })}>
       {/* eslint-disable-next-line jsx-a11y/click-events-have-key-events */}
       <div
diff --git a/packages/docusaurus-theme-classic/src/theme/DocItem/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocItem/index.tsx
index b091503f98..be72fb019f 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocItem/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocItem/index.tsx
@@ -54,7 +54,7 @@ export default function DocItem(props: Props): JSX.Element {
       <div className="row">
         <div
           className={clsx('col', {
-            [styles.docItemCol]: !hideTableOfContents,
+            [styles.docItemCol!]: !hideTableOfContents,
           })}>
           <DocVersionBanner />
           <div className={styles.docItemContainer}>
diff --git a/packages/docusaurus-theme-classic/src/theme/DocPage/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocPage/index.tsx
index b221c8b4bc..3e30820b32 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocPage/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocPage/index.tsx
@@ -74,12 +74,12 @@ function DocPageContent({
               ThemeClassNames.docs.docSidebarContainer,
               styles.docSidebarContainer,
               {
-                [styles.docSidebarContainerHidden]: hiddenSidebarContainer,
+                [styles.docSidebarContainerHidden!]: hiddenSidebarContainer,
               },
             )}
             onTransitionEnd={(e) => {
               if (
-                !e.currentTarget.classList.contains(styles.docSidebarContainer)
+                !e.currentTarget.classList.contains(styles.docSidebarContainer!)
               ) {
                 return;
               }
@@ -126,7 +126,7 @@ function DocPageContent({
         )}
         <main
           className={clsx(styles.docMainContainer, {
-            [styles.docMainContainerEnhanced]:
+            [styles.docMainContainerEnhanced!]:
               hiddenSidebarContainer || !sidebar,
           })}>
           <div
@@ -134,7 +134,7 @@ function DocPageContent({
               'container padding-top--md padding-bottom--lg',
               styles.docItemWrapper,
               {
-                [styles.docItemWrapperEnhanced]: hiddenSidebarContainer,
+                [styles.docItemWrapperEnhanced!]: hiddenSidebarContainer,
               },
             )}>
             <MDXProvider components={MDXComponents}>{children}</MDXProvider>
@@ -172,7 +172,7 @@ export default function DocPage(props: Props): JSX.Element {
         <html className={versionMetadata.className} />
       </Head>
       <DocsVersionProvider version={versionMetadata}>
-        <DocsSidebarProvider sidebar={sidebar}>
+        <DocsSidebarProvider sidebar={sidebar ?? null}>
           <DocPageContent
             currentDocRoute={currentDocRoute}
             versionMetadata={versionMetadata}
diff --git a/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx b/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx
index 77f6e0aae3..5e727e2c46 100644
--- a/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/DocSidebar/index.tsx
@@ -73,13 +73,13 @@ function DocSidebarDesktop({path, sidebar, onCollapse, isHidden}: Props) {
   return (
     <div
       className={clsx(styles.sidebar, {
-        [styles.sidebarWithHideableNavbar]: hideOnScroll,
-        [styles.sidebarHidden]: isHidden,
+        [styles.sidebarWithHideableNavbar!]: hideOnScroll,
+        [styles.sidebarHidden!]: isHidden,
       })}>
       {hideOnScroll && <Logo tabIndex={-1} className={styles.sidebarLogo} />}
       <nav
         className={clsx('menu thin-scrollbar', styles.menu, {
-          [styles.menuWithAnnouncementBar]: showAnnouncementBar,
+          [styles.menuWithAnnouncementBar!]: showAnnouncementBar,
         })}>
         <ul className={clsx(ThemeClassNames.docs.docSidebarMenu, 'menu__list')}>
           <DocSidebarItems items={sidebar} activePath={path} level={1} />
diff --git a/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx b/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx
index bb01173d4a..8b53fb3f90 100644
--- a/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Footer/index.tsx
@@ -131,7 +131,7 @@ function SimpleLinks({links}: {links: SimpleFooter['links']}) {
 function isMultiColumnFooterLinks(
   links: MultiColumnFooter['links'] | SimpleFooter['links'],
 ): links is MultiColumnFooter['links'] {
-  return 'title' in links[0];
+  return 'title' in links[0]!;
 }
 
 function Footer(): JSX.Element | null {
diff --git a/packages/docusaurus-theme-classic/src/theme/Heading/index.tsx b/packages/docusaurus-theme-classic/src/theme/Heading/index.tsx
index c22669cbdf..6608366c49 100644
--- a/packages/docusaurus-theme-classic/src/theme/Heading/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Heading/index.tsx
@@ -26,8 +26,8 @@ function AnchorHeading({as: As, id, ...props}: Props) {
     <As
       {...props}
       className={clsx('anchor', {
-        [styles.anchorWithHideOnScrollNavbar]: hideOnScroll,
-        [styles.anchorWithStickyNavbar]: !hideOnScroll,
+        [styles.anchorWithHideOnScrollNavbar!]: hideOnScroll,
+        [styles.anchorWithStickyNavbar!]: !hideOnScroll,
       })}
       id={id}>
       {props.children}
diff --git a/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx b/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx
index c6afddbc6f..a3f5204ce5 100644
--- a/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/LayoutHead/index.tsx
@@ -92,7 +92,7 @@ export default function LayoutHead(props: Props): JSX.Element {
   const {title, description, image, keywords, searchMetadata} = props;
   const faviconUrl = useBaseUrl(favicon);
   const pageTitle = useTitleFormatter(title);
-  const {htmlLang, direction: htmlDir} = localeConfigs[currentLocale];
+  const {htmlLang, direction: htmlDir} = localeConfigs[currentLocale]!;
 
   return (
     <>
diff --git a/packages/docusaurus-theme-classic/src/theme/Navbar/index.tsx b/packages/docusaurus-theme-classic/src/theme/Navbar/index.tsx
index 84c9259633..10a745646d 100644
--- a/packages/docusaurus-theme-classic/src/theme/Navbar/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Navbar/index.tsx
@@ -241,8 +241,8 @@ export default function Navbar(): JSX.Element {
         'navbar--dark': style === 'dark',
         'navbar--primary': style === 'primary',
         'navbar-sidebar--show': mobileSidebar.shown,
-        [styles.navbarHideable]: hideOnScroll,
-        [styles.navbarHidden]: hideOnScroll && !isNavbarVisible,
+        [styles.navbarHideable!]: hideOnScroll,
+        [styles.navbarHidden!]: hideOnScroll && !isNavbarVisible,
       })}>
       <div className="navbar__inner">
         <div className="navbar__items">
diff --git a/packages/docusaurus-theme-classic/src/theme/NavbarItem/LocaleDropdownNavbarItem/index.tsx b/packages/docusaurus-theme-classic/src/theme/NavbarItem/LocaleDropdownNavbarItem/index.tsx
index 3b950c0348..13e014c4ca 100644
--- a/packages/docusaurus-theme-classic/src/theme/NavbarItem/LocaleDropdownNavbarItem/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/NavbarItem/LocaleDropdownNavbarItem/index.tsx
@@ -28,7 +28,7 @@ export default function LocaleDropdownNavbarItem({
   const alternatePageUtils = useAlternatePageUtils();
 
   function getLocaleLabel(locale: string) {
-    return localeConfigs[locale].label;
+    return localeConfigs[locale]!.label;
   }
 
   const localeItems = locales.map((locale): LinkLikeNavbarItemProps => {
diff --git a/packages/docusaurus-theme-classic/src/theme/TOCCollapsible/index.tsx b/packages/docusaurus-theme-classic/src/theme/TOCCollapsible/index.tsx
index c152e9f948..24b8c100b0 100644
--- a/packages/docusaurus-theme-classic/src/theme/TOCCollapsible/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/TOCCollapsible/index.tsx
@@ -28,7 +28,7 @@ export default function TOCCollapsible({
       className={clsx(
         styles.tocCollapsible,
         {
-          [styles.tocCollapsibleExpanded]: !collapsed,
+          [styles.tocCollapsibleExpanded!]: !collapsed,
         },
         className,
       )}>
diff --git a/packages/docusaurus-theme-classic/src/theme/Tabs/index.tsx b/packages/docusaurus-theme-classic/src/theme/Tabs/index.tsx
index 2e77c4c562..6036ffad40 100644
--- a/packages/docusaurus-theme-classic/src/theme/Tabs/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Tabs/index.tsx
@@ -108,7 +108,7 @@ function TabsComponent(props: Props): JSX.Element {
   ) => {
     const newTab = event.currentTarget;
     const newTabIndex = tabRefs.indexOf(newTab);
-    const newTabValue = values[newTabIndex].value;
+    const newTabValue = values[newTabIndex]!.value;
 
     if (newTabValue !== selectedValue) {
       blockElementScrollPositionUntilNextRender(newTab);
@@ -126,12 +126,12 @@ function TabsComponent(props: Props): JSX.Element {
     switch (event.key) {
       case 'ArrowRight': {
         const nextTab = tabRefs.indexOf(event.currentTarget) + 1;
-        focusElement = tabRefs[nextTab] || tabRefs[0];
+        focusElement = tabRefs[nextTab] || tabRefs[0]!;
         break;
       }
       case 'ArrowLeft': {
         const prevTab = tabRefs.indexOf(event.currentTarget) - 1;
-        focusElement = tabRefs[prevTab] || tabRefs[tabRefs.length - 1];
+        focusElement = tabRefs[prevTab] || tabRefs[tabRefs.length - 1]!;
         break;
       }
       default:
@@ -181,7 +181,7 @@ function TabsComponent(props: Props): JSX.Element {
         cloneElement(
           children.filter(
             (tabItem) => tabItem.props.value === selectedValue,
-          )[0],
+          )[0]!,
           {className: 'margin-vert--md'},
         )
       ) : (
diff --git a/packages/docusaurus-theme-classic/src/theme/Tag/index.tsx b/packages/docusaurus-theme-classic/src/theme/Tag/index.tsx
index 23c5de5b83..019f393379 100644
--- a/packages/docusaurus-theme-classic/src/theme/Tag/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/Tag/index.tsx
@@ -19,8 +19,8 @@ export default function Tag(props: Props): JSX.Element {
     <Link
       href={permalink}
       className={clsx(styles.tag, {
-        [styles.tagRegular]: !count,
-        [styles.tagWithCount]: count,
+        [styles.tagRegular!]: !count,
+        [styles.tagWithCount!]: count,
       })}>
       {name}
       {count && <span>{count}</span>}
diff --git a/packages/docusaurus-theme-classic/src/translations.ts b/packages/docusaurus-theme-classic/src/translations.ts
index 4fb2b6302b..2ec3f97709 100644
--- a/packages/docusaurus-theme-classic/src/translations.ts
+++ b/packages/docusaurus-theme-classic/src/translations.ts
@@ -50,8 +50,11 @@ function getNavbarTranslationFile(navbar: Navbar): TranslationFileContent {
 }
 function translateNavbar(
   navbar: Navbar,
-  navbarTranslations: TranslationFileContent,
+  navbarTranslations: TranslationFileContent | undefined,
 ): Navbar {
+  if (!navbarTranslations) {
+    return navbar;
+  }
   return {
     ...navbar,
     title: navbarTranslations.title?.message ?? navbar.title,
@@ -76,7 +79,7 @@ function translateNavbar(
 function isMultiColumnFooterLinks(
   links: MultiColumnFooter['links'] | SimpleFooter['links'],
 ): links is MultiColumnFooter['links'] {
-  return links.length > 0 && 'title' in links[0];
+  return links.length > 0 && 'title' in links[0]!;
 }
 
 function getFooterTranslationFile(footer: Footer): TranslationFileContent {
@@ -121,8 +124,11 @@ function getFooterTranslationFile(footer: Footer): TranslationFileContent {
 }
 function translateFooter(
   footer: Footer,
-  footerTranslations: TranslationFileContent,
+  footerTranslations: TranslationFileContent | undefined,
 ): Footer {
+  if (!footerTranslations) {
+    return footer;
+  }
   const links = isMultiColumnFooterLinks(footer.links)
     ? footer.links.map((link) => ({
         ...link,
@@ -187,10 +193,10 @@ export function translateThemeConfig({
     ...themeConfig,
     navbar: translateNavbar(
       themeConfig.navbar,
-      translationFilesMap.navbar.content,
+      translationFilesMap.navbar?.content,
     ),
     footer: themeConfig.footer
-      ? translateFooter(themeConfig.footer, translationFilesMap.footer.content)
+      ? translateFooter(themeConfig.footer, translationFilesMap.footer?.content)
       : undefined,
   };
 }
diff --git a/packages/docusaurus-theme-classic/tsconfig.json b/packages/docusaurus-theme-classic/tsconfig.json
index 9840db7cfb..ab5531d36d 100644
--- a/packages/docusaurus-theme-classic/tsconfig.json
+++ b/packages/docusaurus-theme-classic/tsconfig.json
@@ -4,7 +4,7 @@
     "lib": ["DOM", "ES2019"],
     "module": "esnext",
     "noEmit": true,
-    "jsx": "react",
+    "jsx": "react-native",
     "baseUrl": "src"
   },
   "include": ["src/"]
diff --git a/packages/docusaurus-theme-common/src/components/Details/index.tsx b/packages/docusaurus-theme-common/src/components/Details/index.tsx
index ba20f0ca39..e96c3ba517 100644
--- a/packages/docusaurus-theme-common/src/components/Details/index.tsx
+++ b/packages/docusaurus-theme-common/src/components/Details/index.tsx
@@ -58,7 +58,7 @@ export default function Details({
       data-collapsed={collapsed}
       className={clsx(
         styles.details,
-        {[styles.isBrowser]: isBrowser},
+        {[styles.isBrowser!]: isBrowser},
         props.className,
       )}
       onMouseDown={(e) => {
diff --git a/packages/docusaurus-theme-common/src/utils/codeBlockUtils.ts b/packages/docusaurus-theme-common/src/utils/codeBlockUtils.ts
index d7f239489a..1734ae5beb 100644
--- a/packages/docusaurus-theme-common/src/utils/codeBlockUtils.ts
+++ b/packages/docusaurus-theme-common/src/utils/codeBlockUtils.ts
@@ -115,7 +115,7 @@ export function parseLines(
   // Highlighted lines specified in props: don't parse the content
   if (metastring && highlightLinesRangeRegex.test(metastring)) {
     const highlightLinesRange = metastring.match(highlightLinesRangeRegex)!
-      .groups!.range;
+      .groups!.range!;
     const highlightLines = rangeParser(highlightLinesRange)
       .filter((n) => n > 0)
       .map((n) => n - 1);
@@ -131,7 +131,7 @@ export function parseLines(
   let highlightRange = '';
   // loop through lines
   for (let lineNumber = 0; lineNumber < lines.length; ) {
-    const line = lines[lineNumber];
+    const line = lines[lineNumber]!;
     const match = line.match(directiveRegex);
     if (match !== null) {
       const directive = match.slice(1).find((item) => item !== undefined);
diff --git a/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/DocsPreferredVersionProvider.tsx b/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/DocsPreferredVersionProvider.tsx
index dd940cb25a..fb9c534ef4 100644
--- a/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/DocsPreferredVersionProvider.tsx
+++ b/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/DocsPreferredVersionProvider.tsx
@@ -71,7 +71,7 @@ function readStorageState({
       pluginId,
       versionPersistence,
     );
-    const pluginData = allDocsData[pluginId];
+    const pluginData = allDocsData[pluginId]!;
     const versionExists = pluginData.versions.some(
       (version) => version.name === preferredVersionNameUnsafe,
     );
diff --git a/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/useDocsPreferredVersion.ts b/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/useDocsPreferredVersion.ts
index d6da597d91..e035374012 100644
--- a/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/useDocsPreferredVersion.ts
+++ b/packages/docusaurus-theme-common/src/utils/docsPreferredVersion/useDocsPreferredVersion.ts
@@ -25,7 +25,7 @@ export function useDocsPreferredVersion(
   const docsData = useDocsData(pluginId);
   const [state, api] = useDocsPreferredVersionContext();
 
-  const {preferredVersionName} = state[pluginId];
+  const {preferredVersionName} = state[pluginId]!;
 
   const preferredVersion = preferredVersionName
     ? docsData.versions.find((version) => version.name === preferredVersionName)
@@ -49,8 +49,8 @@ export function useDocsPreferredVersionByPluginId(): Record<
   const [state] = useDocsPreferredVersionContext();
 
   function getPluginIdPreferredVersion(pluginId: string) {
-    const docsData = allDocsData[pluginId];
-    const {preferredVersionName} = state[pluginId];
+    const docsData = allDocsData[pluginId]!;
+    const {preferredVersionName} = state[pluginId]!;
 
     return preferredVersionName
       ? docsData.versions.find(
diff --git a/packages/docusaurus-theme-common/src/utils/tagsUtils.ts b/packages/docusaurus-theme-common/src/utils/tagsUtils.ts
index edd29f2c8f..fa51bd99a9 100644
--- a/packages/docusaurus-theme-common/src/utils/tagsUtils.ts
+++ b/packages/docusaurus-theme-common/src/utils/tagsUtils.ts
@@ -19,7 +19,7 @@ type TagsListItem = Readonly<{name: string; permalink: string; count: number}>;
 export type TagLetterEntry = Readonly<{letter: string; tags: TagsListItem[]}>;
 
 function getTagLetter(tag: string): string {
-  return tag[0].toUpperCase();
+  return tag[0]!.toUpperCase();
 }
 
 export function listTagsByLetters(
@@ -29,8 +29,8 @@ export function listTagsByLetters(
   const groups: Record<string, TagsListItem[]> = {};
   Object.values(tags).forEach((tag) => {
     const letter = getTagLetter(tag.name);
-    groups[letter] = groups[letter] ?? [];
-    groups[letter].push(tag);
+    groups[letter] ??= [];
+    groups[letter]!.push(tag);
   });
 
   return (
diff --git a/packages/docusaurus-theme-common/src/utils/tocUtils.ts b/packages/docusaurus-theme-common/src/utils/tocUtils.ts
index 6f00ebc3db..d02ed1b472 100644
--- a/packages/docusaurus-theme-common/src/utils/tocUtils.ts
+++ b/packages/docusaurus-theme-common/src/utils/tocUtils.ts
@@ -44,7 +44,7 @@ function treeifyTOC(flatTOC: readonly TOCItem[]): TOCTreeNode[] {
   headings.forEach((heading) => {
     const {parentIndex, ...rest} = heading;
     if (parentIndex >= 0) {
-      headings[parentIndex].children.push(rest);
+      headings[parentIndex]!.children.push(rest);
     } else {
       rootNodes.push(rest);
     }
diff --git a/packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts b/packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts
index d47cf84956..3461777f7e 100644
--- a/packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts
+++ b/packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts
@@ -34,7 +34,9 @@ export function useContextualSearchFilters(): useContextualSearchFiltersReturns
 
     const preferredVersion = docsPreferredVersionByPluginId[pluginId];
 
-    const latestVersion = allDocsData[pluginId].versions.find((v) => v.isLast)!;
+    const latestVersion = allDocsData[pluginId]!.versions.find(
+      (v) => v.isLast,
+    )!;
 
     const version = activeVersion ?? preferredVersion ?? latestVersion;
 
diff --git a/packages/docusaurus-theme-common/src/utils/usePluralForm.ts b/packages/docusaurus-theme-common/src/utils/usePluralForm.ts
index 15cac1f72c..7397235a3f 100644
--- a/packages/docusaurus-theme-common/src/utils/usePluralForm.ts
+++ b/packages/docusaurus-theme-common/src/utils/usePluralForm.ts
@@ -99,7 +99,7 @@ function selectPluralMessage(
   const parts = pluralMessages.split(separator);
 
   if (parts.length === 1) {
-    return parts[0];
+    return parts[0]!;
   }
   if (parts.length > localePluralForms.pluralForms.length) {
     console.error(
@@ -110,7 +110,7 @@ function selectPluralMessage(
   const pluralFormIndex = localePluralForms.pluralForms.indexOf(pluralForm);
   // In case of not enough plural form messages, we take the last one (other)
   // instead of returning undefined
-  return parts[Math.min(pluralFormIndex, parts.length - 1)];
+  return parts[Math.min(pluralFormIndex, parts.length - 1)]!;
 }
 
 export function usePluralForm(): {
diff --git a/packages/docusaurus-theme-common/src/utils/useTOCHighlight.ts b/packages/docusaurus-theme-common/src/utils/useTOCHighlight.ts
index b8ab0db1d6..e46d335bf2 100644
--- a/packages/docusaurus-theme-common/src/utils/useTOCHighlight.ts
+++ b/packages/docusaurus-theme-common/src/utils/useTOCHighlight.ts
@@ -83,7 +83,7 @@ function getActiveAnchor(
   }
   // no anchor under viewport top? (ie we are at the bottom of the page)
   // => highlight the last anchor found
-  return anchors[anchors.length - 1];
+  return anchors[anchors.length - 1] ?? null;
 }
 
 function getLinkAnchorValue(link: HTMLAnchorElement): string {
diff --git a/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx b/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx
index 323b9d0e33..61daf2266c 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx
+++ b/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx
@@ -58,7 +58,7 @@ function useDocsSearchVersionsHelpers() {
       Object.entries(allDocsData).reduce(
         (acc, [pluginId, pluginData]) => ({
           ...acc,
-          [pluginId]: pluginData.versions[0].name,
+          [pluginId]: pluginData.versions[0]!.name,
         }),
         {},
       ),
@@ -277,7 +277,7 @@ export default function SearchPage(): JSX.Element {
           const {
             isIntersecting,
             boundingClientRect: {y: currentY},
-          } = entries[0];
+          } = entries[0]!;
 
           if (isIntersecting && prevY.current > currentY) {
             searchResultStateDispatcher({type: 'advance'});
diff --git a/packages/docusaurus-utils-common/src/applyTrailingSlash.ts b/packages/docusaurus-utils-common/src/applyTrailingSlash.ts
index ee7e38f743..d8faa439cc 100644
--- a/packages/docusaurus-utils-common/src/applyTrailingSlash.ts
+++ b/packages/docusaurus-utils-common/src/applyTrailingSlash.ts
@@ -41,7 +41,7 @@ export default function applyTrailingSlash(
   }
 
   // The trailing slash should be handled before the ?search#hash !
-  const [pathname] = path.split(/[#?]/);
+  const [pathname] = path.split(/[#?]/) as [string, ...string[]];
 
   // Never transform '/' to ''
   // Never remove the baseUrl trailing slash!
diff --git a/packages/docusaurus-utils/src/constants.ts b/packages/docusaurus-utils/src/constants.ts
index 8d1bb8a2d5..156038ffe0 100644
--- a/packages/docusaurus-utils/src/constants.ts
+++ b/packages/docusaurus-utils/src/constants.ts
@@ -6,11 +6,11 @@
  */
 
 export const NODE_MAJOR_VERSION = parseInt(
-  process.versions.node.split('.')[0],
+  process.versions.node.split('.')[0]!,
   10,
 );
 export const NODE_MINOR_VERSION = parseInt(
-  process.versions.node.split('.')[1],
+  process.versions.node.split('.')[1]!,
   10,
 );
 
diff --git a/packages/docusaurus-utils/src/markdownLinks.ts b/packages/docusaurus-utils/src/markdownLinks.ts
index 405de8c29b..e9eed1a7e6 100644
--- a/packages/docusaurus-utils/src/markdownLinks.ts
+++ b/packages/docusaurus-utils/src/markdownLinks.ts
@@ -48,12 +48,13 @@ export function replaceMarkdownLinks<T extends ContentPaths>({
   let lastCodeFence = '';
   const lines = fileString.split('\n').map((line) => {
     if (line.trim().startsWith('```')) {
+      const codeFence = line.trim().match(/^`+/)![0]!;
       if (!fencedBlock) {
         fencedBlock = true;
-        [lastCodeFence] = line.trim().match(/^`+/)!;
+        lastCodeFence = codeFence;
         // If we are in a ````-fenced block, all ``` would be plain text instead
         // of fences
-      } else if (line.trim().match(/^`+/)![0].length >= lastCodeFence.length) {
+      } else if (codeFence.length >= lastCodeFence.length) {
         fencedBlock = false;
       }
     }
@@ -71,7 +72,7 @@ export function replaceMarkdownLinks<T extends ContentPaths>({
     let mdMatch = mdRegex.exec(modifiedLine);
     while (mdMatch !== null) {
       // Replace it to correct html link.
-      const mdLink = mdMatch.groups!.filename;
+      const mdLink = mdMatch.groups!.filename!;
 
       const sourcesToTry = [
         path.resolve(path.dirname(filePath), decodeURIComponent(mdLink)),
diff --git a/packages/docusaurus-utils/src/markdownParser.ts b/packages/docusaurus-utils/src/markdownParser.ts
index c1a1007e51..108300c107 100644
--- a/packages/docusaurus-utils/src/markdownParser.ts
+++ b/packages/docusaurus-utils/src/markdownParser.ts
@@ -18,8 +18,8 @@ export function parseMarkdownHeadingId(heading: string): {
   const matches = customHeadingIdRegex.exec(heading);
   if (matches) {
     return {
-      text: matches.groups!.text,
-      id: matches.groups!.id,
+      text: matches.groups!.text!,
+      id: matches.groups!.id!,
     };
   }
   return {text: heading, id: undefined};
@@ -51,14 +51,13 @@ export function createExcerpt(fileString: string): string | undefined {
 
     // Skip code block line.
     if (fileLine.trim().startsWith('```')) {
+      const codeFence = fileLine.trim().match(/^`+/)![0]!;
       if (!inCode) {
         inCode = true;
-        [lastCodeFence] = fileLine.trim().match(/^`+/)!;
+        lastCodeFence = codeFence;
         // If we are in a ````-fenced block, all ``` would be plain text instead
         // of fences
-      } else if (
-        fileLine.trim().match(/^`+/)![0].length >= lastCodeFence.length
-      ) {
+      } else if (codeFence.length >= lastCodeFence.length) {
         inCode = false;
       }
       continue;
diff --git a/packages/docusaurus-utils/src/tags.ts b/packages/docusaurus-utils/src/tags.ts
index 4c347faa33..37addba4aa 100644
--- a/packages/docusaurus-utils/src/tags.ts
+++ b/packages/docusaurus-utils/src/tags.ts
@@ -80,13 +80,13 @@ export function groupTaggedItems<Item>(
     // TODO: it's not really clear what should be the behavior if 2 items have
     // the same tag but the permalink is different for each
     // For now, the first tag found wins
-    result[tag.permalink] = result[tag.permalink] ?? {
+    result[tag.permalink] ??= {
       tag,
       items: [],
     };
 
     // Add item to group
-    result[tag.permalink].items.push(item);
+    result[tag.permalink]!.items.push(item);
   }
 
   items.forEach((item) => {
diff --git a/packages/docusaurus-utils/src/urlUtils.ts b/packages/docusaurus-utils/src/urlUtils.ts
index 9a69596651..0f1d24f540 100644
--- a/packages/docusaurus-utils/src/urlUtils.ts
+++ b/packages/docusaurus-utils/src/urlUtils.ts
@@ -15,10 +15,17 @@ export function normalizeUrl(rawUrls: string[]): string {
   let hasStartingSlash = false;
   let hasEndingSlash = false;
 
+  const isNonEmptyArray = (arr: string[]): arr is [string, ...string[]] =>
+    arr.length > 0;
+
+  if (!isNonEmptyArray(urls)) {
+    return '';
+  }
+
   // If the first part is a plain protocol, we combine it with the next part.
   if (urls[0].match(/^[^/:]+:\/*$/) && urls.length > 1) {
-    const first = urls.shift();
-    if (first!.startsWith('file:') && urls[0].startsWith('/')) {
+    const first = urls.shift()!;
+    if (first.startsWith('file:') && urls[0].startsWith('/')) {
       // Force a double slash here, else we lose the information that the next
       // segment is an absolute path
       urls[0] = `${first}//${urls[0]}`;
diff --git a/packages/docusaurus/src/choosePort.ts b/packages/docusaurus/src/choosePort.ts
index fbf8469093..618df3e69e 100644
--- a/packages/docusaurus/src/choosePort.ts
+++ b/packages/docusaurus/src/choosePort.ts
@@ -38,7 +38,7 @@ function clearConsole(): void {
 function getProcessIdOnPort(port: number): string {
   return execSync(`lsof -i:${port} -P -t -sTCP:LISTEN`, execOptions)
     .toString()
-    .split('\n')[0]
+    .split('\n')[0]!
     .trim();
 }
 
diff --git a/packages/docusaurus/src/client/PendingNavigation.tsx b/packages/docusaurus/src/client/PendingNavigation.tsx
index 050dd1a900..56e7e9c062 100644
--- a/packages/docusaurus/src/client/PendingNavigation.tsx
+++ b/packages/docusaurus/src/client/PendingNavigation.tsx
@@ -45,7 +45,7 @@ class PendingNavigation extends React.Component<Props, State> {
 
   // Intercept location update and still show current route until next route
   // is done loading.
-  shouldComponentUpdate(nextProps: Props, nextState: State) {
+  override shouldComponentUpdate(nextProps: Props, nextState: State) {
     const routeDidChange = nextProps.location !== this.props.location;
     const {routes, delay} = this.props;
 
@@ -116,7 +116,7 @@ class PendingNavigation extends React.Component<Props, State> {
     nprogress.done();
   }
 
-  render() {
+  override render() {
     const {children, location} = this.props;
     return (
       <Route location={normalizeLocation(location)} render={() => children} />
diff --git a/packages/docusaurus/src/client/exports/ComponentCreator.tsx b/packages/docusaurus/src/client/exports/ComponentCreator.tsx
index 45e479a39a..8dc312b8d9 100644
--- a/packages/docusaurus/src/client/exports/ComponentCreator.tsx
+++ b/packages/docusaurus/src/client/exports/ComponentCreator.tsx
@@ -27,7 +27,7 @@ export default function ComponentCreator(
   }
 
   const chunkNamesKey = `${path}-${hash}`;
-  const chunkNames = routesChunkNames[chunkNamesKey];
+  const chunkNames = routesChunkNames[chunkNamesKey]!;
   const optsModules: string[] = [];
   const optsWebpack: string[] = [];
   const optsLoader: OptsLoader = {};
@@ -47,8 +47,8 @@ export default function ComponentCreator(
     ]
   */
   const flatChunkNames = flat(chunkNames);
-  Object.keys(flatChunkNames).forEach((key) => {
-    const chunkRegistry = registry[flatChunkNames[key]];
+  Object.entries(flatChunkNames).forEach(([key, chunkName]) => {
+    const chunkRegistry = registry[chunkName];
     if (chunkRegistry) {
       // eslint-disable-next-line prefer-destructuring
       optsLoader[key] = chunkRegistry[0];
@@ -68,16 +68,16 @@ export default function ComponentCreator(
       Object.keys(loaded).forEach((key) => {
         let val = loadedModules;
         const keyPath = key.split('.');
-        for (let i = 0; i < keyPath.length - 1; i += 1) {
-          val = val[keyPath[i]];
-        }
-        val[keyPath[keyPath.length - 1]] = loaded[key].default;
+        keyPath.slice(0, -1).forEach((k) => {
+          val = val[k];
+        });
+        val[keyPath[keyPath.length - 1]!] = loaded[key].default;
         const nonDefaultKeys = Object.keys(loaded[key]).filter(
           (k) => k !== 'default',
         );
         if (nonDefaultKeys && nonDefaultKeys.length) {
           nonDefaultKeys.forEach((nonDefaultKey) => {
-            val[keyPath[keyPath.length - 1]][nonDefaultKey] =
+            val[keyPath[keyPath.length - 1]!][nonDefaultKey] =
               loaded[key][nonDefaultKey];
           });
         }
diff --git a/packages/docusaurus/src/client/exports/ErrorBoundary.tsx b/packages/docusaurus/src/client/exports/ErrorBoundary.tsx
index e8937d3aa8..9b9515898a 100644
--- a/packages/docusaurus/src/client/exports/ErrorBoundary.tsx
+++ b/packages/docusaurus/src/client/exports/ErrorBoundary.tsx
@@ -21,14 +21,14 @@ export default class ErrorBoundary extends React.Component<Props, State> {
     this.state = {error: null};
   }
 
-  componentDidCatch(error: Error): void {
+  override componentDidCatch(error: Error): void {
     // Catch errors in any components below and re-render with error message
     if (ExecutionEnvironment.canUseDOM) {
       this.setState({error});
     }
   }
 
-  render(): ReactNode {
+  override render(): ReactNode {
     const {children} = this.props;
     const {error} = this.state;
 
diff --git a/packages/docusaurus/src/client/exports/Translate.tsx b/packages/docusaurus/src/client/exports/Translate.tsx
index 4c059d8055..8e9c0f8fcc 100644
--- a/packages/docusaurus/src/client/exports/Translate.tsx
+++ b/packages/docusaurus/src/client/exports/Translate.tsx
@@ -25,7 +25,7 @@ function getLocalizedMessage({
     );
   }
 
-  return codeTranslations[(id ?? message)!] ?? message ?? id;
+  return codeTranslations[(id ?? message)!] ?? message ?? id!;
 }
 
 // Imperative translation API is useful for some edge-cases:
diff --git a/packages/docusaurus/src/client/flat.ts b/packages/docusaurus/src/client/flat.ts
index 9252f0f466..d1c7fe5fea 100644
--- a/packages/docusaurus/src/client/flat.ts
+++ b/packages/docusaurus/src/client/flat.ts
@@ -15,8 +15,7 @@ export default function flat(target: RouteChunksTree): Record<string, string> {
   const output: Record<string, string> = {};
 
   function step(object: RouteChunksTree, prefix?: string | number) {
-    Object.keys(object).forEach((key: string | number) => {
-      const value = object[key];
+    Object.entries(object).forEach(([key, value]) => {
       const newKey = prefix ? `${prefix}${delimiter}${key}` : key;
 
       if (isTree(value)) {
diff --git a/packages/docusaurus/src/client/prefetch.ts b/packages/docusaurus/src/client/prefetch.ts
index fb4057c0b2..338f1b14fb 100644
--- a/packages/docusaurus/src/client/prefetch.ts
+++ b/packages/docusaurus/src/client/prefetch.ts
@@ -37,9 +37,9 @@ function linkPrefetchStrategy(url: string) {
     link.onerror = reject;
 
     const parentElement =
-      document.getElementsByTagName('head')[0] ||
-      document.getElementsByName('script')[0].parentNode;
-    parentElement.appendChild(link);
+      document.getElementsByTagName('head')[0] ??
+      document.getElementsByName('script')[0]?.parentNode;
+    parentElement?.appendChild(link);
   });
 }
 
diff --git a/packages/docusaurus/src/client/serverEntry.tsx b/packages/docusaurus/src/client/serverEntry.tsx
index b850a73d30..8fda0bcd75 100644
--- a/packages/docusaurus/src/client/serverEntry.tsx
+++ b/packages/docusaurus/src/client/serverEntry.tsx
@@ -75,7 +75,7 @@ async function doRender(locals: Locals & {path: string}) {
     ssrTemplate,
     noIndex,
   } = locals;
-  const location = routesLocation[locals.path];
+  const location = routesLocation[locals.path]!;
   await preload(routes, location);
   const modules = new Set<string>();
   const context = {};
diff --git a/packages/docusaurus/src/client/theme-fallback/Root/index.tsx b/packages/docusaurus/src/client/theme-fallback/Root/index.tsx
index 0f9f5e0299..0e09dc1f42 100644
--- a/packages/docusaurus/src/client/theme-fallback/Root/index.tsx
+++ b/packages/docusaurus/src/client/theme-fallback/Root/index.tsx
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import type {ReactNode} from 'react';
+import React, {type ReactNode} from 'react';
 
 // Wrapper at the very top of the app, that is applied constantly
 // and does not depend on current route (unlike the layout)
@@ -14,6 +14,6 @@ import type {ReactNode} from 'react';
 // and these providers won't reset state when we navigate
 //
 // See https://github.com/facebook/docusaurus/issues/3919
-export default function Root({children}: {children: ReactNode}): ReactNode {
-  return children;
+export default function Root({children}: {children: ReactNode}): JSX.Element {
+  return <>{children}</>;
 }
diff --git a/packages/docusaurus/src/commands/build.ts b/packages/docusaurus/src/commands/build.ts
index 94b2f7e4b3..bc1e7f557a 100644
--- a/packages/docusaurus/src/commands/build.ts
+++ b/packages/docusaurus/src/commands/build.ts
@@ -79,7 +79,7 @@ export default async function build(
 
   // We need the default locale to always be the 1st in the list. If we build it
   // last, it would "erase" the localized sites built in sub-folders
-  const orderedLocales: string[] = [
+  const orderedLocales: [string, ...string[]] = [
     i18n.defaultLocale,
     ...i18n.locales.filter((locale) => locale !== i18n.defaultLocale),
   ];
@@ -89,7 +89,7 @@ export default async function build(
       orderedLocales.indexOf(locale) === orderedLocales.length - 1;
     return tryToBuildLocale({locale, isLastLocale});
   });
-  return results[0];
+  return results[0]!;
 }
 
 async function buildLocale({
diff --git a/packages/docusaurus/src/commands/swizzle/context.ts b/packages/docusaurus/src/commands/swizzle/context.ts
index 92722262a6..f4ca176f09 100644
--- a/packages/docusaurus/src/commands/swizzle/context.ts
+++ b/packages/docusaurus/src/commands/swizzle/context.ts
@@ -30,7 +30,7 @@ export async function initSwizzleContext(
 
   return {
     plugins: plugins.map((plugin, pluginIndex) => ({
-      plugin: pluginsNormalized[pluginIndex],
+      plugin: pluginsNormalized[pluginIndex]!,
       instance: plugin,
     })),
   };
diff --git a/packages/docusaurus/src/server/brokenLinks.ts b/packages/docusaurus/src/server/brokenLinks.ts
index 4f3f6b4f12..77d697433a 100644
--- a/packages/docusaurus/src/server/brokenLinks.ts
+++ b/packages/docusaurus/src/server/brokenLinks.ts
@@ -35,7 +35,7 @@ type BrokenLink = {
 
 // matchRoutes does not support qs/anchors, so we remove it!
 function onlyPathname(link: string) {
-  return link.split('#')[0].split('?')[0];
+  return link.split('#')[0]!.split('?')[0]!;
 }
 
 function getPageBrokenLinks({
diff --git a/packages/docusaurus/src/server/index.ts b/packages/docusaurus/src/server/index.ts
index 79e38c2549..6a943a487e 100644
--- a/packages/docusaurus/src/server/index.ts
+++ b/packages/docusaurus/src/server/index.ts
@@ -359,13 +359,13 @@ export default ${JSON.stringify(siteConfig, null, 2)};`,
     generatedFilesDir,
     'registry.js',
     `export default {
-${Object.keys(registry)
-  .sort()
+${Object.entries(registry)
+  .sort((a, b) => a[0].localeCompare(b[0]))
   .map(
-    (key) =>
-      `  '${key}': [${registry[key].loader}, '${escapePath(
-        registry[key].modulePath,
-      )}', require.resolveWeak('${escapePath(registry[key].modulePath)}')],`,
+    ([key, chunk]) =>
+      `  '${key}': [${chunk.loader}, '${escapePath(
+        chunk.modulePath,
+      )}', require.resolveWeak('${escapePath(chunk.modulePath)}')],`,
   )
   .join('\n')}};\n`,
   );
diff --git a/packages/docusaurus/src/server/plugins/index.ts b/packages/docusaurus/src/server/plugins/index.ts
index 5599e26b60..ef63e6bee9 100644
--- a/packages/docusaurus/src/server/plugins/index.ts
+++ b/packages/docusaurus/src/server/plugins/index.ts
@@ -126,7 +126,7 @@ export async function loadPlugins({
     .mapValues((nameItems) =>
       _.chain(nameItems)
         .groupBy((item) => item.options.id ?? DEFAULT_PLUGIN_ID)
-        .mapValues((idItems) => idItems[0].content)
+        .mapValues((idItems) => idItems[0]!.content)
         .value(),
     )
     .value();
@@ -177,7 +177,7 @@ export async function loadPlugins({
           data,
         ) => {
           globalData[plugin.name] = globalData[plugin.name] ?? {};
-          globalData[plugin.name][pluginId] = data;
+          globalData[plugin.name]![pluginId] = data;
         };
 
         const actions: PluginContentLoadedActions = {
diff --git a/packages/docusaurus/src/server/routes.ts b/packages/docusaurus/src/server/routes.ts
index 0c3dcb4acd..ad91a94fb5 100644
--- a/packages/docusaurus/src/server/routes.ts
+++ b/packages/docusaurus/src/server/routes.ts
@@ -249,8 +249,8 @@ function genRouteChunkNames(
   }
 
   const newValue: ChunkNames = {};
-  Object.keys(value).forEach((key) => {
-    newValue[key] = genRouteChunkNames(registry, value[key], key, name);
+  Object.entries(value).forEach(([key, v]) => {
+    newValue[key] = genRouteChunkNames(registry, v, key, name);
   });
   return newValue;
 }
diff --git a/packages/docusaurus/src/server/themes/index.ts b/packages/docusaurus/src/server/themes/index.ts
index 3a201c1b8e..51b114846b 100644
--- a/packages/docusaurus/src/server/themes/index.ts
+++ b/packages/docusaurus/src/server/themes/index.ts
@@ -20,7 +20,7 @@ export async function loadThemeAliases(
 
   for (const themePath of themePaths) {
     const themeAliases = await themeAlias(themePath, true);
-    Object.keys(themeAliases).forEach((aliasKey) => {
+    Object.entries(themeAliases).forEach(([aliasKey, alias]) => {
       // If this alias shadows a previous one, use @theme-init to preserve the
       // initial one. @theme-init is only applied once: to the initial theme
       // that provided this component
@@ -28,10 +28,10 @@ export async function loadThemeAliases(
         const componentName = aliasKey.substring(aliasKey.indexOf('/') + 1);
         const initAlias = `@theme-init/${componentName}`;
         if (!(initAlias in aliases)) {
-          aliases[initAlias] = aliases[aliasKey];
+          aliases[initAlias] = aliases[aliasKey]!;
         }
       }
-      aliases[aliasKey] = themeAliases[aliasKey];
+      aliases[aliasKey] = alias;
     });
   }
 
diff --git a/packages/docusaurus/src/server/translations/translationsExtractor.ts b/packages/docusaurus/src/server/translations/translationsExtractor.ts
index 069f789203..d626645de7 100644
--- a/packages/docusaurus/src/server/translations/translationsExtractor.ts
+++ b/packages/docusaurus/src/server/translations/translationsExtractor.ts
@@ -340,7 +340,7 @@ ${sourceWarningPart(path.node)}`,
 
         const args = path.get('arguments');
         if (args.length === 1 || args.length === 2) {
-          const firstArgPath = args[0];
+          const firstArgPath = args[0]!;
 
           // translate("x" + "y"); => translate("xy");
           const firstArgEvaluated = firstArgPath.evaluate();
diff --git a/packages/docusaurus/src/webpack/plugins/ChunkAssetPlugin.ts b/packages/docusaurus/src/webpack/plugins/ChunkAssetPlugin.ts
index 731f11491c..ea2f4fd349 100644
--- a/packages/docusaurus/src/webpack/plugins/ChunkAssetPlugin.ts
+++ b/packages/docusaurus/src/webpack/plugins/ChunkAssetPlugin.ts
@@ -25,11 +25,12 @@ export default class ChunkAssetPlugin {
     compiler.hooks.thisCompilation.tap(pluginName, ({mainTemplate}) => {
       mainTemplate.hooks.requireExtensions.tap(pluginName, (source, chunk) => {
         const chunkIdToName = chunk.getChunkMaps(false).name;
-        const chunkNameToId = Object.create(null);
-        Object.keys(chunkIdToName).forEach((chunkId) => {
-          const chunkName = chunkIdToName[chunkId];
-          chunkNameToId[chunkName] = chunkId;
-        });
+        const chunkNameToId = Object.fromEntries(
+          Object.entries(chunkIdToName).map(([chunkId, chunkName]) => [
+            chunkName,
+            chunkId,
+          ]),
+        );
         const buf = [source];
         buf.push('// function to get chunk asset');
         buf.push(
diff --git a/packages/docusaurus/src/webpack/plugins/LogPlugin.ts b/packages/docusaurus/src/webpack/plugins/LogPlugin.ts
index 512fbf6872..e8e79b0080 100644
--- a/packages/docusaurus/src/webpack/plugins/LogPlugin.ts
+++ b/packages/docusaurus/src/webpack/plugins/LogPlugin.ts
@@ -14,7 +14,7 @@ function showError(arr: string[]) {
 }
 
 export default class LogPlugin extends WebpackBar {
-  apply(compiler: Compiler): void {
+  override apply(compiler: Compiler): void {
     super.apply(compiler);
 
     // TODO can't this be done in compile(configs) alongside the warnings???
diff --git a/packages/docusaurus/tsconfig.json b/packages/docusaurus/tsconfig.json
index af81dee451..cabe532baa 100644
--- a/packages/docusaurus/tsconfig.json
+++ b/packages/docusaurus/tsconfig.json
@@ -5,7 +5,6 @@
     "tsBuildInfoFile": "./lib/.tsbuildinfo",
     "rootDir": "src",
     "outDir": "lib",
-    "jsx": "react",
     "allowJs": true
   },
   "include": ["src"],
diff --git a/packages/lqip-loader/src/index.ts b/packages/lqip-loader/src/index.ts
index f60c25406f..f42e6b21d5 100644
--- a/packages/lqip-loader/src/index.ts
+++ b/packages/lqip-loader/src/index.ts
@@ -39,7 +39,7 @@ export default async function lqipLoader(
   if (contentIsUrlExport) {
     source = content.match(
       /^(?:export default|module.exports =) (?<source>.*)/,
-    )!.groups!.source;
+    )!.groups!.source!;
   } else {
     if (!contentIsFileExport) {
       // eslint-disable-next-line global-require, @typescript-eslint/no-var-requires
@@ -48,7 +48,7 @@ export default async function lqipLoader(
     }
     source = content.match(
       /^(?:export default|module.exports =) (?<source>.*);/,
-    )!.groups!.source;
+    )!.groups!.source!;
   }
 
   const outputPromises: [Promise<string> | null, Promise<string[]> | null] = [
diff --git a/packages/lqip-loader/src/lqip.ts b/packages/lqip-loader/src/lqip.ts
index eb16ed33a8..68226b0c5b 100644
--- a/packages/lqip-loader/src/lqip.ts
+++ b/packages/lqip-loader/src/lqip.ts
@@ -25,14 +25,15 @@ const SUPPORTED_MIMES: Record<string, string> = {
 export async function base64(file: string): Promise<string> {
   let extension = path.extname(file);
   extension = extension.split('.').pop()!;
+  const mime = SUPPORTED_MIMES[extension];
 
-  if (!SUPPORTED_MIMES[extension]) {
+  if (!mime) {
     throw new Error(ERROR_EXT);
   }
 
   try {
     const data = await sharp(file).resize(10).toBuffer();
-    return toBase64(SUPPORTED_MIMES[extension], data);
+    return toBase64(mime, data);
   } catch (err) {
     logger.error`Generation of base64 failed for image path=${file}.`;
     throw err;
diff --git a/tsconfig.json b/tsconfig.json
index 84f1f5a9e6..cb10e8a5cc 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,42 +1,48 @@
 {
   "compilerOptions": {
+    /* Emit */
     "target": "ES2020",
     "module": "commonjs",
     "lib": ["ESNext", "DOM"],
     "declaration": true,
     "declarationMap": false,
     "jsx": "react",
+    "importHelpers": true,
+    "noEmitHelpers": true,
 
     /* Strict Type-Checking Options */
-    "strict": true,
-    "strictNullChecks": true,
-    "strictFunctionTypes": true,
-    "strictBindCallApply": true,
-    "strictPropertyInitialization": true,
-    "noImplicitThis": true,
-    "alwaysStrict": true,
-
-    /* Additional Checks */
-    "noUnusedLocals": false, // ensured by eslint, should not block compilation
-    "noImplicitReturns": true,
+    "allowUnreachableCode": false,
+    // Too hard to turn on
+    "exactOptionalPropertyTypes": false,
     "noFallthroughCasesInSwitch": true,
-
-    /* Disabled on purpose (handled by ESLint, should not block compilation) */
+    "noImplicitOverride": true,
+    "noImplicitReturns": true,
+    // `process.env` is usually accessed as property
+    "noPropertyAccessFromIndexSignature": false,
+    "noUncheckedIndexedAccess": true,
+    /* strict family */
+    "strict": true,
+    "alwaysStrict": true,
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictBindCallApply": true,
+    "strictFunctionTypes": true,
+    "strictNullChecks": true,
+    "strictPropertyInitialization": true,
+    "useUnknownInCatchVariables": true,
+    /* Handled by ESLint */
+    "noUnusedLocals": false,
     "noUnusedParameters": false,
+    "importsNotUsedAsValues": "remove",
 
-    /* Module Resolution Options */
+    /* Module Resolution */
     "moduleResolution": "node",
+    "resolveJsonModule": true,
     "allowSyntheticDefaultImports": true,
     "esModuleInterop": true,
+    "forceConsistentCasingInFileNames": true,
     "isolatedModules": true,
-
-    /* Advanced Options */
-    "resolveJsonModule": true,
-    "skipLibCheck": true, // @types/webpack and webpack/types.d.ts are not the same thing
-
-    /* Use tslib */
-    "importHelpers": true,
-    "noEmitHelpers": true
+    "skipLibCheck": true // @types/webpack and webpack/types.d.ts are not the same thing
   },
   "exclude": ["node_modules", "**/__tests__/**/*", "**/lib/**/*"]
 }