diff --git a/templates/base/footer_content.tmpl b/templates/base/footer_content.tmpl
index 4b9d9f5bbe..60eb2fe1f8 100644
--- a/templates/base/footer_content.tmpl
+++ b/templates/base/footer_content.tmpl
@@ -17,12 +17,12 @@
 		{{end}}
 	</div>
 	<div class="right-links" role="group" aria-label="{{ctx.Locale.Tr "aria.footer.links"}}">
-		<div class="ui dropdown upward language">
+		<div class="ui dropdown upward">
 			<span class="flex-text-inline">{{svg "octicon-globe" 14}} {{ctx.Locale.LangName}}</span>
 			<div class="menu language-menu">
-				{{range .AllLangs}}
-					<a lang="{{.Lang}}" data-url="{{AppSubUrl}}/?lang={{.Lang}}" class="item {{if eq ctx.Locale.Lang .Lang}}active selected{{end}}">{{.Name}}</a>
-				{{end}}
+				{{range .AllLangs -}}
+				<a lang="{{.Lang}}" data-url="{{AppSubUrl}}/?lang={{.Lang}}" class="item {{if eq ctx.Locale.Lang .Lang}}selected{{end}}">{{.Name}}</a>
+				{{end -}}
 			</div>
 		</div>
 		<a href="{{AssetUrlPrefix}}/licenses.txt">{{ctx.Locale.Tr "licenses"}}</a>
diff --git a/web_src/css/home.css b/web_src/css/home.css
index 28992ef31f..77d2ecf92b 100644
--- a/web_src/css/home.css
+++ b/web_src/css/home.css
@@ -73,7 +73,7 @@
   margin-left: 5px;
 }
 
-.page-footer .ui.dropdown.language .menu {
+.page-footer .ui.dropdown .menu.language-menu {
   max-height: min(500px, calc(100vh - 60px));
   overflow-y: auto;
   margin-bottom: 10px;
diff --git a/web_src/js/features/common-page.ts b/web_src/js/features/common-page.ts
index 77fe2cc1ca..beec92d152 100644
--- a/web_src/js/features/common-page.ts
+++ b/web_src/js/features/common-page.ts
@@ -1,6 +1,7 @@
-import $ from 'jquery';
 import {GET} from '../modules/fetch.ts';
 import {showGlobalErrorMessage} from '../bootstrap.ts';
+import {fomanticQuery} from '../modules/fomantic/base.ts';
+import {queryElems} from '../utils/dom.ts';
 
 const {appUrl} = window.config;
 
@@ -17,18 +18,18 @@ export function initHeadNavbarContentToggle() {
 }
 
 export function initFootLanguageMenu() {
-  async function linkLanguageAction() {
-    const $this = $(this);
-    await GET($this.data('url'));
+  document.querySelector('.ui.dropdown .menu.language-menu')?.addEventListener('click', async (e) => {
+    const item = (e.target as HTMLElement).closest('.item');
+    if (!item) return;
+    e.preventDefault();
+    await GET(item.getAttribute('data-url'));
     window.location.reload();
-  }
-
-  $('.language-menu a[lang]').on('click', linkLanguageAction);
+  });
 }
 
 export function initGlobalDropdown() {
   // Semantic UI modules.
-  const $uiDropdowns = $('.ui.dropdown');
+  const $uiDropdowns = fomanticQuery('.ui.dropdown');
 
   // do not init "custom" dropdowns, "custom" dropdowns are managed by their own code.
   $uiDropdowns.filter(':not(.custom)').dropdown();
@@ -46,14 +47,14 @@ export function initGlobalDropdown() {
     },
     onHide() {
       this._tippy?.enable();
+      // eslint-disable-next-line unicorn/no-this-assignment
+      const elDropdown = this;
 
       // hide all tippy elements of items after a while. eg: use Enter to click "Copy Link" in the Issue Context Menu
       setTimeout(() => {
-        const $dropdown = $(this);
+        const $dropdown = fomanticQuery(elDropdown);
         if ($dropdown.dropdown('is hidden')) {
-          $(this).find('.menu > .item').each((_, item) => {
-            item._tippy?.hide();
-          });
+          queryElems(elDropdown, '.menu > .item', (el) => el._tippy?.hide());
         }
       }, 2000);
     },
@@ -71,7 +72,7 @@ export function initGlobalDropdown() {
 }
 
 export function initGlobalTabularMenu() {
-  $('.ui.menu.tabular:not(.custom) .item').tab({autoTabActivation: false});
+  fomanticQuery('.ui.menu.tabular:not(.custom) .item').tab({autoTabActivation: false});
 }
 
 /**
diff --git a/web_src/js/features/imagediff.ts b/web_src/js/features/imagediff.ts
index a6b1f48fb3..cd61888f83 100644
--- a/web_src/js/features/imagediff.ts
+++ b/web_src/js/features/imagediff.ts
@@ -1,14 +1,14 @@
-import $ from 'jquery';
 import {GET} from '../modules/fetch.ts';
 import {hideElem, loadElem, queryElemChildren, queryElems} from '../utils/dom.ts';
 import {parseDom} from '../utils.ts';
+import {fomanticQuery} from '../modules/fomantic/base.ts';
 
 function getDefaultSvgBoundsIfUndefined(text, src) {
   const defaultSize = 300;
   const maxSize = 99999;
 
   const svgDoc = parseDom(text, 'image/svg+xml');
-  const svg = svgDoc.documentElement;
+  const svg = (svgDoc.documentElement as unknown) as SVGSVGElement;
   const width = svg?.width?.baseVal;
   const height = svg?.height?.baseVal;
   if (width === undefined || height === undefined) {
@@ -68,12 +68,14 @@ function createContext(imageAfter, imageBefore) {
 }
 
 class ImageDiff {
-  async init(containerEl) {
+  containerEl: HTMLElement;
+  diffContainerWidth: number;
+
+  async init(containerEl: HTMLElement) {
     this.containerEl = containerEl;
     containerEl.setAttribute('data-image-diff-loaded', 'true');
 
-    // the only jQuery usage in this file
-    $(containerEl).find('.ui.menu.tabular .item').tab({autoTabActivation: false});
+    fomanticQuery(containerEl).find('.ui.menu.tabular .item').tab({autoTabActivation: false});
 
     // the container may be hidden by "viewed" checkbox, so use the parent's width for reference
     this.diffContainerWidth = Math.max(containerEl.closest('.diff-file-box').clientWidth - 300, 100);
@@ -81,12 +83,12 @@ class ImageDiff {
     const imageInfos = [{
       path: containerEl.getAttribute('data-path-after'),
       mime: containerEl.getAttribute('data-mime-after'),
-      images: containerEl.querySelectorAll('img.image-after'), // matches 3 <img>
+      images: containerEl.querySelectorAll<HTMLImageElement>('img.image-after'), // matches 3 <img>
       boundsInfo: containerEl.querySelector('.bounds-info-after'),
     }, {
       path: containerEl.getAttribute('data-path-before'),
       mime: containerEl.getAttribute('data-mime-before'),
-      images: containerEl.querySelectorAll('img.image-before'), // matches 3 <img>
+      images: containerEl.querySelectorAll<HTMLImageElement>('img.image-before'), // matches 3 <img>
       boundsInfo: containerEl.querySelector('.bounds-info-before'),
     }];
 
@@ -102,8 +104,8 @@ class ImageDiff {
         const bounds = getDefaultSvgBoundsIfUndefined(text, info.path);
         if (bounds) {
           for (const el of info.images) {
-            el.setAttribute('width', bounds.width);
-            el.setAttribute('height', bounds.height);
+            el.setAttribute('width', String(bounds.width));
+            el.setAttribute('height', String(bounds.height));
           }
           hideElem(info.boundsInfo);
         }
@@ -151,7 +153,7 @@ class ImageDiff {
       const boundsInfoBeforeHeight = this.containerEl.querySelector('.bounds-info-before .bounds-info-height');
       if (boundsInfoBeforeHeight) {
         boundsInfoBeforeHeight.textContent = `${sizes.imageBefore.naturalHeight}px`;
-        boundsInfoBeforeHeight.classList.add('red', heightChanged);
+        boundsInfoBeforeHeight.classList.toggle('red', heightChanged);
       }
     }
 
@@ -205,7 +207,7 @@ class ImageDiff {
     }
 
     // extra height for inner "position: absolute" elements
-    const swipe = this.containerEl.querySelector('.diff-swipe');
+    const swipe = this.containerEl.querySelector<HTMLElement>('.diff-swipe');
     if (swipe) {
       swipe.style.width = `${sizes.maxSize.width * factor + 2}px`;
       swipe.style.height = `${sizes.maxSize.height * factor + 30}px`;
@@ -225,7 +227,7 @@ class ImageDiff {
       const rect = swipeFrame.getBoundingClientRect();
       const value = Math.max(0, Math.min(e.clientX - rect.left, width));
       swipeBar.style.left = `${value}px`;
-      this.containerEl.querySelector('.swipe-container').style.width = `${swipeFrame.clientWidth - value}px`;
+      this.containerEl.querySelector<HTMLElement>('.swipe-container').style.width = `${swipeFrame.clientWidth - value}px`;
     };
     const removeEventListeners = () => {
       document.removeEventListener('mousemove', onSwipeMouseMove);
@@ -264,11 +266,11 @@ class ImageDiff {
       overlayFrame.style.height = `${sizes.maxSize.height * factor + 2}px`;
     }
 
-    const rangeInput = this.containerEl.querySelector('input[type="range"]');
+    const rangeInput = this.containerEl.querySelector<HTMLInputElement>('input[type="range"]');
 
     function updateOpacity() {
       if (sizes.imageAfter) {
-        sizes.imageAfter.parentNode.style.opacity = `${rangeInput.value / 100}`;
+        sizes.imageAfter.parentNode.style.opacity = `${Number(rangeInput.value) / 100}`;
       }
     }
 
@@ -278,7 +280,7 @@ class ImageDiff {
 }
 
 export function initImageDiff() {
-  for (const el of queryElems('.image-diff:not([data-image-diff-loaded])')) {
+  for (const el of queryElems<HTMLImageElement>(document, '.image-diff:not([data-image-diff-loaded])')) {
     (new ImageDiff()).init(el); // it is async, but we don't need to await for it
   }
 }
diff --git a/web_src/js/features/repo-common.ts b/web_src/js/features/repo-common.ts
index c7d84de9f0..c246d5b4b0 100644
--- a/web_src/js/features/repo-common.ts
+++ b/web_src/js/features/repo-common.ts
@@ -31,7 +31,7 @@ async function onDownloadArchive(e) {
 }
 
 export function initRepoArchiveLinks() {
-  queryElems('a.archive-link[href]', (el) => el.addEventListener('click', onDownloadArchive));
+  queryElems(document, 'a.archive-link[href]', (el) => el.addEventListener('click', onDownloadArchive));
 }
 
 export function initRepoActivityTopAuthorsChart() {
diff --git a/web_src/js/features/repo-editor.ts b/web_src/js/features/repo-editor.ts
index e4d179d3ae..6ea9347eba 100644
--- a/web_src/js/features/repo-editor.ts
+++ b/web_src/js/features/repo-editor.ts
@@ -45,17 +45,17 @@ export function initRepoEditor() {
   const dropzoneUpload = document.querySelector('.page-content.repository.editor.upload .dropzone');
   if (dropzoneUpload) initDropzone(dropzoneUpload);
 
-  const editArea = document.querySelector('.page-content.repository.editor textarea#edit_area');
+  const editArea = document.querySelector<HTMLTextAreaElement>('.page-content.repository.editor textarea#edit_area');
   if (!editArea) return;
 
-  for (const el of queryElems('.js-quick-pull-choice-option')) {
+  for (const el of queryElems<HTMLInputElement>(document, '.js-quick-pull-choice-option')) {
     el.addEventListener('input', () => {
       if (el.value === 'commit-to-new-branch') {
         showElem('.quick-pull-branch-name');
-        document.querySelector('.quick-pull-branch-name input').required = true;
+        document.querySelector<HTMLInputElement>('.quick-pull-branch-name input').required = true;
       } else {
         hideElem('.quick-pull-branch-name');
-        document.querySelector('.quick-pull-branch-name input').required = false;
+        document.querySelector<HTMLInputElement>('.quick-pull-branch-name input').required = false;
       }
       document.querySelector('#commit-button').textContent = el.getAttribute('data-button-text');
     });
@@ -71,13 +71,13 @@ export function initRepoEditor() {
     if (filenameInput.value) {
       parts.push(filenameInput.value);
     }
-    document.querySelector('#tree_path').value = parts.join('/');
+    document.querySelector<HTMLInputElement>('#tree_path').value = parts.join('/');
   }
   filenameInput.addEventListener('input', function () {
     const parts = filenameInput.value.split('/');
     const links = Array.from(document.querySelectorAll('.breadcrumb span.section'));
     const dividers = Array.from(document.querySelectorAll('.breadcrumb .breadcrumb-divider'));
-    let warningDiv = document.querySelector('.ui.warning.message.flash-message.flash-warning.space-related');
+    let warningDiv = document.querySelector<HTMLDivElement>('.ui.warning.message.flash-message.flash-warning.space-related');
     let containSpace = false;
     if (parts.length > 1) {
       for (let i = 0; i < parts.length; ++i) {
@@ -110,14 +110,14 @@ export function initRepoEditor() {
           filenameInput.value = value;
         }
         this.setSelectionRange(0, 0);
-        containSpace |= (trimValue !== value && trimValue !== '');
+        containSpace = containSpace || (trimValue !== value && trimValue !== '');
       }
     }
-    containSpace |= Array.from(links).some((link) => {
+    containSpace = containSpace || Array.from(links).some((link) => {
       const value = link.querySelector('a').textContent;
       return value.trim() !== value;
     });
-    containSpace |= parts[parts.length - 1].trim() !== parts[parts.length - 1];
+    containSpace = containSpace || parts[parts.length - 1].trim() !== parts[parts.length - 1];
     if (containSpace) {
       if (!warningDiv) {
         warningDiv = document.createElement('div');
@@ -135,8 +135,8 @@ export function initRepoEditor() {
     joinTreePath();
   });
   filenameInput.addEventListener('keydown', function (e) {
-    const sections = queryElems('.breadcrumb span.section');
-    const dividers = queryElems('.breadcrumb .breadcrumb-divider');
+    const sections = queryElems(document, '.breadcrumb span.section');
+    const dividers = queryElems(document, '.breadcrumb .breadcrumb-divider');
     // Jump back to last directory once the filename is empty
     if (e.code === 'Backspace' && filenameInput.selectionStart === 0 && sections.length > 0) {
       e.preventDefault();
@@ -159,7 +159,7 @@ export function initRepoEditor() {
 
     // Using events from https://github.com/codedance/jquery.AreYouSure#advanced-usage
     // to enable or disable the commit button
-    const commitButton = document.querySelector('#commit-button');
+    const commitButton = document.querySelector<HTMLButtonElement>('#commit-button');
     const $editForm = $('.ui.edit.form');
     const dirtyFileClass = 'dirty-file';
 
diff --git a/web_src/js/features/repo-settings.ts b/web_src/js/features/repo-settings.ts
index 34a3b635b2..72213f794a 100644
--- a/web_src/js/features/repo-settings.ts
+++ b/web_src/js/features/repo-settings.ts
@@ -8,7 +8,7 @@ const {appSubUrl, csrfToken} = window.config;
 
 function initRepoSettingsCollaboration() {
   // Change collaborator access mode
-  for (const dropdownEl of queryElems('.page-content.repository .ui.dropdown.access-mode')) {
+  for (const dropdownEl of queryElems(document, '.page-content.repository .ui.dropdown.access-mode')) {
     const textEl = dropdownEl.querySelector(':scope > .text');
     $(dropdownEl).dropdown({
       async action(text, value) {
diff --git a/web_src/js/modules/fomantic/base.ts b/web_src/js/modules/fomantic/base.ts
index 7574fdd25c..10b5ed014f 100644
--- a/web_src/js/modules/fomantic/base.ts
+++ b/web_src/js/modules/fomantic/base.ts
@@ -1,3 +1,4 @@
+import $ from 'jquery';
 let ariaIdCounter = 0;
 
 export function generateAriaId() {
@@ -16,3 +17,6 @@ export function linkLabelAndInput(label, input) {
     label.setAttribute('for', id);
   }
 }
+
+// eslint-disable-next-line no-jquery/variable-pattern
+export const fomanticQuery = $;
diff --git a/web_src/js/modules/tippy.ts b/web_src/js/modules/tippy.ts
index d75015f69e..7948e3ecbc 100644
--- a/web_src/js/modules/tippy.ts
+++ b/web_src/js/modules/tippy.ts
@@ -179,11 +179,9 @@ export function initGlobalTooltips() {
 }
 
 export function showTemporaryTooltip(target: Element, content: Content) {
-  // if the target is inside a dropdown, don't show the tooltip because when the dropdown
-  // closes, the tippy would be pushed unsightly to the top-left of the screen like seen
-  // on the issue comment menu.
-  if (target.closest('.ui.dropdown > .menu')) return;
-
+  // if the target is inside a dropdown, the menu will be hidden soon
+  // so display the tooltip on the dropdown instead
+  target = target.closest('.ui.dropdown') || target;
   const tippy = target._tippy ?? attachTooltip(target, content);
   tippy.setContent(content);
   if (!tippy.state.isShown) tippy.show();
diff --git a/web_src/js/utils/dom.ts b/web_src/js/utils/dom.ts
index e2a4c60e84..79ce05a7ad 100644
--- a/web_src/js/utils/dom.ts
+++ b/web_src/js/utils/dom.ts
@@ -5,7 +5,7 @@ import type $ from 'jquery';
 type ElementArg = Element | string | NodeListOf<Element> | Array<Element> | ReturnType<typeof $>;
 type ElementsCallback = (el: Element) => Promisable<any>;
 type ElementsCallbackWithArgs = (el: Element, ...args: any[]) => Promisable<any>;
-type IterableElements = NodeListOf<Element> | Array<Element>;
+type ArrayLikeIterable<T> = ArrayLike<T> & Iterable<T>; // for NodeListOf and Array
 
 function elementsCall(el: ElementArg, func: ElementsCallbackWithArgs, ...args: any[]) {
   if (typeof el === 'string' || el instanceof String) {
@@ -15,7 +15,7 @@ function elementsCall(el: ElementArg, func: ElementsCallbackWithArgs, ...args: a
     func(el, ...args);
   } else if (el.length !== undefined) {
     // this works for: NodeList, HTMLCollection, Array, jQuery
-    for (const e of (el as IterableElements)) {
+    for (const e of (el as ArrayLikeIterable<Element>)) {
       func(e, ...args);
     }
   } else {
@@ -58,7 +58,7 @@ export function isElemHidden(el: ElementArg) {
   return res[0];
 }
 
-function applyElemsCallback(elems: IterableElements, fn?: ElementsCallback) {
+function applyElemsCallback<T extends Element>(elems: ArrayLikeIterable<T>, fn?: ElementsCallback): ArrayLikeIterable<T> {
   if (fn) {
     for (const el of elems) {
       fn(el);
@@ -67,19 +67,22 @@ function applyElemsCallback(elems: IterableElements, fn?: ElementsCallback) {
   return elems;
 }
 
-export function queryElemSiblings(el: Element, selector = '*', fn?: ElementsCallback) {
-  return applyElemsCallback(Array.from(el.parentNode.children).filter((child: Element) => {
+export function queryElemSiblings<T extends Element>(el: Element, selector = '*', fn?: ElementsCallback): ArrayLikeIterable<T> {
+  const elems = Array.from(el.parentNode.children) as T[];
+  return applyElemsCallback<T>(elems.filter((child: Element) => {
     return child !== el && child.matches(selector);
   }), fn);
 }
 
 // it works like jQuery.children: only the direct children are selected
-export function queryElemChildren(parent: Element | ParentNode, selector = '*', fn?: ElementsCallback) {
-  return applyElemsCallback(parent.querySelectorAll(`:scope > ${selector}`), fn);
+export function queryElemChildren<T extends Element>(parent: Element | ParentNode, selector = '*', fn?: ElementsCallback): ArrayLikeIterable<T> {
+  return applyElemsCallback<T>(parent.querySelectorAll(`:scope > ${selector}`), fn);
 }
 
-export function queryElems(selector: string, fn?: ElementsCallback) {
-  return applyElemsCallback(document.querySelectorAll(selector), fn);
+// it works like parent.querySelectorAll: all descendants are selected
+// in the future, all "queryElems(document, ...)" should be refactored to use a more specific parent
+export function queryElems<T extends Element>(parent: Element | ParentNode, selector: string, fn?: ElementsCallback): ArrayLikeIterable<T> {
+  return applyElemsCallback<T>(parent.querySelectorAll(selector), fn);
 }
 
 export function onDomReady(cb: () => Promisable<void>) {
@@ -92,7 +95,7 @@ export function onDomReady(cb: () => Promisable<void>) {
 
 // checks whether an element is owned by the current document, and whether it is a document fragment or element node
 // if it is, it means it is a "normal" element managed by us, which can be modified safely.
-export function isDocumentFragmentOrElementNode(el: Element | Node) {
+export function isDocumentFragmentOrElementNode(el: Node) {
   try {
     return el.ownerDocument === document && el.nodeType === Node.ELEMENT_NODE || el.nodeType === Node.DOCUMENT_FRAGMENT_NODE;
   } catch {