diff --git a/assets/js/autocomplete.js b/assets/js/autocomplete.ts
similarity index 52%
rename from assets/js/autocomplete.js
rename to assets/js/autocomplete.ts
index 8ec0f278..19bdfff0 100644
--- a/assets/js/autocomplete.js
+++ b/assets/js/autocomplete.ts
@@ -6,52 +6,67 @@ import { LocalAutocompleter } from './utils/local-autocompleter';
 import { handleError } from './utils/requests';
 import { getTermContexts } from './match_query';
 import store from './utils/store';
+import { TermContext } from './query/lex.ts';
+import { $, $$, makeEl, removeEl } from './utils/dom.ts';
 
-const cache = {};
-/** @type {HTMLInputElement} */
-let inputField,
-  /** @type {string} */
-  originalTerm,
-  /** @type {string} */
-  originalQuery,
-  /** @type {TermContext} */
-  selectedTerm;
+type TermSuggestion = {
+  label: string;
+  value: string;
+};
+
+const cachedSuggestions: Record<string, TermSuggestion[]> = {};
+let inputField: HTMLInputElement | null = null,
+  originalTerm: string | undefined,
+  originalQuery: string | undefined,
+  selectedTerm: TermContext | null = null;
 
 function removeParent() {
-  const parent = document.querySelector('.autocomplete');
-  if (parent) parent.parentNode.removeChild(parent);
+  const parent = $<HTMLElement>('.autocomplete');
+  if (parent) removeEl(parent);
 }
 
 function removeSelected() {
-  const selected = document.querySelector('.autocomplete__item--selected');
+  const selected = $<HTMLElement>('.autocomplete__item--selected');
   if (selected) selected.classList.remove('autocomplete__item--selected');
 }
 
-function isSearchField() {
-  return inputField && inputField.dataset.acMode === 'search';
+function isSearchField(targetInput: HTMLElement) {
+  return targetInput && targetInput.dataset.acMode === 'search';
 }
 
 function restoreOriginalValue() {
-  inputField.value = isSearchField() ? originalQuery : originalTerm;
+  if (!inputField) {
+    return;
+  }
+
+  if (isSearchField(inputField) && originalQuery) {
+    inputField.value = originalQuery;
+  }
+
+  if (originalTerm) {
+    inputField.value = originalTerm;
+  }
 }
 
-function applySelectedValue(selection) {
-  if (!isSearchField()) {
+function applySelectedValue(selection: string) {
+  if (!inputField) {
+    return;
+  }
+
+  if (!isSearchField(inputField)) {
     inputField.value = selection;
     return;
   }
 
-  if (!selectedTerm) {
-    return;
+  if (selectedTerm && originalQuery) {
+    const [startIndex, endIndex] = selectedTerm[0];
+    inputField.value = originalQuery.slice(0, startIndex) + selection + originalQuery.slice(endIndex);
+    inputField.setSelectionRange(startIndex + selection.length, startIndex + selection.length);
+    inputField.focus();
   }
-
-  const [startIndex, endIndex] = selectedTerm[0];
-  inputField.value = originalQuery.slice(0, startIndex) + selection + originalQuery.slice(endIndex);
-  inputField.setSelectionRange(startIndex + selection.length, startIndex + selection.length);
-  inputField.focus();
 }
 
-function changeSelected(firstOrLast, current, sibling) {
+function changeSelected(firstOrLast: Element | null, current: Element | null, sibling: Element | null) {
   if (current && sibling) {
     // if the currently selected item has a sibling, move selection to it
     current.classList.remove('autocomplete__item--selected');
@@ -67,18 +82,21 @@ function changeSelected(firstOrLast, current, sibling) {
 }
 
 function isSelectionOutsideCurrentTerm() {
+  if (!inputField || !selectedTerm) return true;
+  if (inputField.selectionStart === null || inputField.selectionEnd === null) return true;
+
   const selectionIndex = Math.min(inputField.selectionStart, inputField.selectionEnd);
   const [startIndex, endIndex] = selectedTerm[0];
 
   return startIndex > selectionIndex || endIndex < selectionIndex;
 }
 
-function keydownHandler(event) {
-  const selected = document.querySelector('.autocomplete__item--selected'),
-    firstItem = document.querySelector('.autocomplete__item:first-of-type'),
-    lastItem = document.querySelector('.autocomplete__item:last-of-type');
+function keydownHandler(event: KeyboardEvent) {
+  const selected = $<HTMLElement>('.autocomplete__item--selected'),
+    firstItem = $<HTMLElement>('.autocomplete__item:first-of-type'),
+    lastItem = $<HTMLElement>('.autocomplete__item:last-of-type');
 
-  if (isSearchField()) {
+  if (inputField && isSearchField(inputField)) {
     // Prevent submission of the search field when Enter was hit
     if (selected && event.keyCode === 13) event.preventDefault(); // Enter
 
@@ -91,20 +109,21 @@ function keydownHandler(event) {
     }
   }
 
-  if (event.keyCode === 38) changeSelected(lastItem, selected, selected && selected.previousSibling); // ArrowUp
-  if (event.keyCode === 40) changeSelected(firstItem, selected, selected && selected.nextSibling); // ArrowDown
+  if (event.keyCode === 38) changeSelected(lastItem, selected, selected && selected.previousElementSibling); // ArrowUp
+  if (event.keyCode === 40) changeSelected(firstItem, selected, selected && selected.nextElementSibling); // ArrowDown
   if (event.keyCode === 13 || event.keyCode === 27 || event.keyCode === 188) removeParent(); // Enter || Esc || Comma
   if (event.keyCode === 38 || event.keyCode === 40) {
     // ArrowUp || ArrowDown
-    const newSelected = document.querySelector('.autocomplete__item--selected');
-    if (newSelected) applySelectedValue(newSelected.dataset.value);
+    const newSelected = $<HTMLElement>('.autocomplete__item--selected');
+    if (newSelected?.dataset.value) applySelectedValue(newSelected.dataset.value);
     event.preventDefault();
   }
 }
 
-function createItem(list, suggestion) {
-  const item = document.createElement('li');
-  item.className = 'autocomplete__item';
+function createItem(list: HTMLUListElement, suggestion: TermSuggestion) {
+  const item = makeEl('li', {
+    className: 'autocomplete__item',
+  });
 
   item.textContent = suggestion.label;
   item.dataset.value = suggestion.value;
@@ -119,7 +138,10 @@ function createItem(list, suggestion) {
   });
 
   item.addEventListener('click', () => {
+    if (!inputField || !item.dataset.value) return;
+
     applySelectedValue(item.dataset.value);
+
     inputField.dispatchEvent(
       new CustomEvent('autocomplete', {
         detail: {
@@ -134,66 +156,71 @@ function createItem(list, suggestion) {
   list.appendChild(item);
 }
 
-function createList(suggestions) {
-  const parent = document.querySelector('.autocomplete'),
-    list = document.createElement('ul');
-  list.className = 'autocomplete__list';
+function createList(parentElement: HTMLElement, suggestions: TermSuggestion[]) {
+  const list = makeEl('ul', {
+    className: 'autocomplete__list',
+  });
 
   suggestions.forEach(suggestion => createItem(list, suggestion));
 
-  parent.appendChild(list);
+  parentElement.appendChild(list);
 }
 
-function createParent() {
-  const parent = document.createElement('div');
+function createParent(): HTMLElement {
+  const parent = makeEl('div');
   parent.className = 'autocomplete';
 
-  // Position the parent below the inputfield
-  parent.style.position = 'absolute';
-  parent.style.left = `${inputField.offsetLeft}px`;
-  // Take the inputfield offset, add its height and subtract the amount by which the parent element has scrolled
-  parent.style.top = `${inputField.offsetTop + inputField.offsetHeight - inputField.parentNode.scrollTop}px`;
+  if (inputField && inputField.parentElement) {
+    // Position the parent below the inputfield
+    parent.style.position = 'absolute';
+    parent.style.left = `${inputField.offsetLeft}px`;
+    // Take the inputfield offset, add its height and subtract the amount by which the parent element has scrolled
+    parent.style.top = `${inputField.offsetTop + inputField.offsetHeight - inputField.parentElement.scrollTop}px`;
+  }
 
   // We append the parent at the end of body
   document.body.appendChild(parent);
+
+  return parent;
 }
 
-function showAutocomplete(suggestions, fetchedTerm, targetInput) {
+function showAutocomplete(suggestions: TermSuggestion[], fetchedTerm: string, targetInput: HTMLInputElement) {
   // Remove old autocomplete suggestions
   removeParent();
 
   // Save suggestions in cache
-  cache[fetchedTerm] = suggestions;
+  cachedSuggestions[fetchedTerm] = suggestions;
 
   // If the input target is not empty, still visible, and suggestions were found
   if (targetInput.value && targetInput.style.display !== 'none' && suggestions.length) {
-    createParent();
-    createList(suggestions);
-    inputField.addEventListener('keydown', keydownHandler);
+    createList(createParent(), suggestions);
+    targetInput.addEventListener('keydown', keydownHandler);
   }
 }
 
-function getSuggestions(term) {
+async function getSuggestions(term: string): Promise<TermSuggestion[]> {
   // In case source URL was not given at all, do not try sending the request.
-  if (!inputField.dataset.acSource) return [];
-  return fetch(`${inputField.dataset.acSource}${term}`).then(response => response.json());
+  if (!inputField?.dataset.acSource) return [];
+
+  return await fetch(`${inputField.dataset.acSource}${term}`)
+    .then(handleError)
+    .then(response => response.json());
 }
 
-function getSelectedTerm() {
-  if (!inputField || !originalQuery) {
-    return null;
-  }
+function getSelectedTerm(): TermContext | null {
+  if (!inputField || !originalQuery) return null;
+  if (inputField.selectionStart === null || inputField.selectionEnd === null) return null;
 
   const selectionIndex = Math.min(inputField.selectionStart, inputField.selectionEnd);
   const terms = getTermContexts(originalQuery);
 
-  return terms.find(([range]) => range[0] < selectionIndex && range[1] >= selectionIndex);
+  return terms.find(([range]) => range[0] < selectionIndex && range[1] >= selectionIndex) ?? null;
 }
 
 function toggleSearchAutocomplete() {
   const enable = store.get('enable_search_ac');
 
-  for (const searchField of document.querySelectorAll('input[data-ac-mode=search]')) {
+  for (const searchField of $$<HTMLInputElement>('input[data-ac-mode=search]')) {
     if (enable) {
       searchField.autocomplete = 'off';
     } else {
@@ -204,10 +231,9 @@ function toggleSearchAutocomplete() {
 }
 
 function listenAutocomplete() {
-  let timeout;
+  let timeout: number | undefined;
 
-  /** @type {LocalAutocompleter} */
-  let localAc = null;
+  let localAc: LocalAutocompleter | null = null;
   let localFetched = false;
 
   document.addEventListener('focusin', fetchLocalAutocomplete);
@@ -217,11 +243,15 @@ function listenAutocomplete() {
     fetchLocalAutocomplete(event);
     window.clearTimeout(timeout);
 
-    if (localAc !== null && 'ac' in event.target.dataset) {
-      inputField = event.target;
+    if (!(event.target instanceof HTMLInputElement)) return;
+
+    const targetedInput = event.target;
+
+    if (localAc !== null && 'ac' in targetedInput.dataset) {
+      inputField = targetedInput;
       let suggestionsCount = 5;
 
-      if (isSearchField()) {
+      if (isSearchField(inputField)) {
         originalQuery = inputField.value;
         selectedTerm = getSelectedTerm();
         suggestionsCount = 10;
@@ -242,29 +272,31 @@ function listenAutocomplete() {
         .map(({ name, imageCount }) => ({ label: `${name} (${imageCount})`, value: name }));
 
       if (suggestions.length) {
-        return showAutocomplete(suggestions, originalTerm, event.target);
+        return showAutocomplete(suggestions, originalTerm, targetedInput);
       }
     }
 
     // Use a timeout to delay requests until the user has stopped typing
     timeout = window.setTimeout(() => {
-      inputField = event.target;
+      inputField = targetedInput;
       originalTerm = inputField.value;
 
       const fetchedTerm = inputField.value;
       const { ac, acMinLength, acSource } = inputField.dataset;
 
-      if (ac && acSource && fetchedTerm.length >= acMinLength) {
-        if (cache[fetchedTerm]) {
-          showAutocomplete(cache[fetchedTerm], fetchedTerm, event.target);
-        } else {
-          // inputField could get overwritten while the suggestions are being fetched - use event.target
-          getSuggestions(fetchedTerm).then(suggestions => {
-            if (fetchedTerm === event.target.value) {
-              showAutocomplete(suggestions, fetchedTerm, event.target);
-            }
-          });
-        }
+      if (!ac || !acSource || (acMinLength && fetchedTerm.length < parseInt(acMinLength, 10))) {
+        return;
+      }
+
+      if (cachedSuggestions[fetchedTerm]) {
+        showAutocomplete(cachedSuggestions[fetchedTerm], fetchedTerm, targetedInput);
+      } else {
+        // inputField could get overwritten while the suggestions are being fetched - use event.target
+        getSuggestions(fetchedTerm).then(suggestions => {
+          if (fetchedTerm === targetedInput.value) {
+            showAutocomplete(suggestions, fetchedTerm, targetedInput);
+          }
+        });
       }
     }, 300);
   });
@@ -272,10 +304,14 @@ function listenAutocomplete() {
   // If there's a click outside the inputField, remove autocomplete
   document.addEventListener('click', event => {
     if (event.target && event.target !== inputField) removeParent();
-    if (event.target === inputField && isSearchField() && isSelectionOutsideCurrentTerm()) removeParent();
+    if (inputField && event.target === inputField && isSearchField(inputField) && isSelectionOutsideCurrentTerm()) {
+      removeParent();
+    }
   });
 
-  function fetchLocalAutocomplete(event) {
+  function fetchLocalAutocomplete(event: Event) {
+    if (!(event.target instanceof HTMLInputElement)) return;
+
     if (!localFetched && event.target.dataset && 'ac' in event.target.dataset) {
       const now = new Date();
       const cacheKey = `${now.getUTCFullYear()}-${now.getUTCMonth()}-${now.getUTCDate()}`;