wip(js): add head.html and assets/js

assets/js/modules/components.js

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+export { categoryCollapse } from './components/category-collapse';
+export { initClipboard } from './components/clipboard';
+export { loadImg } from './components/img-loading';
+export { imgPopup } from './components/img-popup';
+export { initLocaleDatetime } from './components/locale-datetime';
+export { initToc } from './components/toc';
+export { loadMermaid } from './components/mermaid';
+export { modeWatcher } from './components/mode-toggle';
+export { back2top } from './components/back-to-top';
+export { loadTooptip } from './components/tooltip-loader';

assets/js/modules/components/back-to-top.js

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+/**
+ * Reference: https://bootsnipp.com/snippets/featured/link-to-top-page
+ */
+
+export function back2top() {
+  const btn = document.getElementById('back-to-top');
+
+  window.addEventListener('scroll', () => {
+    if (window.scrollY > 50) {
+      btn.classList.add('show');
+    } else {
+      btn.classList.remove('show');
+    }
+  });
+
+  btn.addEventListener('click', () => {
+    window.scrollTo({ top: 0 });
+  });
+}

assets/js/modules/components/category-collapse.js

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+/**
+ * Tab 'Categories' expand/close effect.
+ */
+
+import 'bootstrap/js/src/collapse.js';
+
+const childPrefix = 'l_';
+const parentPrefix = 'h_';
+const children = document.getElementsByClassName('collapse');
+
+export function categoryCollapse() {
+  [...children].forEach((elem) => {
+    const id = parentPrefix + elem.id.substring(childPrefix.length);
+    const parent = document.getElementById(id);
+
+    // collapse sub-categories
+    elem.addEventListener('hide.bs.collapse', () => {
+      if (parent) {
+        parent.querySelector('.far.fa-folder-open').className =
+          'far fa-folder fa-fw';
+        parent.querySelector('.fas.fa-angle-down').classList.add('rotate');
+        parent.classList.remove('hide-border-bottom');
+      }
+    });
+
+    // expand sub-categories
+    elem.addEventListener('show.bs.collapse', () => {
+      if (parent) {
+        parent.querySelector('.far.fa-folder').className =
+          'far fa-folder-open fa-fw';
+        parent.querySelector('.fas.fa-angle-down').classList.remove('rotate');
+        parent.classList.add('hide-border-bottom');
+      }
+    });
+  });
+}

assets/js/modules/components/clipboard.js

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+/**
+ * Clipboard functions
+ *
+ * Dependencies:
+ *    clipboard.js (https://github.com/zenorocha/clipboard.js)
+ */
+
+import Tooltip from 'bootstrap/js/src/tooltip';
+
+const clipboardSelector = '.code-header>button';
+
+const ICON_DEFAULT = 'far fa-clipboard';
+const ICON_SUCCESS = 'fas fa-check';
+
+const ATTR_TIMEOUT = 'timeout';
+const ATTR_TITLE_SUCCEED = 'data-title-succeed';
+const ATTR_TITLE_ORIGIN = 'data-bs-original-title';
+const TIMEOUT = 2000; // in milliseconds
+
+function isLocked(node) {
+  if (node.hasAttribute(ATTR_TIMEOUT)) {
+    let timeout = node.getAttribute(ATTR_TIMEOUT);
+    if (Number(timeout) > Date.now()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+function lock(node) {
+  node.setAttribute(ATTR_TIMEOUT, Date.now() + TIMEOUT);
+}
+
+function unlock(node) {
+  node.removeAttribute(ATTR_TIMEOUT);
+}
+
+function showTooltip(btn) {
+  const succeedTitle = btn.getAttribute(ATTR_TITLE_SUCCEED);
+  btn.setAttribute(ATTR_TITLE_ORIGIN, succeedTitle);
+  Tooltip.getInstance(btn).show();
+}
+
+function hideTooltip(btn) {
+  Tooltip.getInstance(btn).hide();
+  btn.removeAttribute(ATTR_TITLE_ORIGIN);
+}
+
+function setSuccessIcon(btn) {
+  const icon = btn.children[0];
+  icon.setAttribute('class', ICON_SUCCESS);
+}
+
+function resumeIcon(btn) {
+  const icon = btn.children[0];
+  icon.setAttribute('class', ICON_DEFAULT);
+}
+
+function setCodeClipboard() {
+  const clipboardList = document.querySelectorAll(clipboardSelector);
+
+  if (clipboardList.length === 0) {
+    return;
+  }
+
+  // Initial the clipboard.js object
+  const clipboard = new ClipboardJS(clipboardSelector, {
+    target: (trigger) => {
+      const codeBlock = trigger.parentNode.nextElementSibling;
+      return codeBlock.querySelector('code .rouge-code');
+    }
+  });
+
+  [...clipboardList].map(
+    (elem) =>
+      new Tooltip(elem, {
+        placement: 'left'
+      })
+  );
+
+  clipboard.on('success', (e) => {
+    const trigger = e.trigger;
+
+    e.clearSelection();
+
+    if (isLocked(trigger)) {
+      return;
+    }
+
+    setSuccessIcon(trigger);
+    showTooltip(trigger);
+    lock(trigger);
+
+    setTimeout(() => {
+      hideTooltip(trigger);
+      resumeIcon(trigger);
+      unlock(trigger);
+    }, TIMEOUT);
+  });
+}
+
+function setLinkClipboard() {
+  const btnCopyLink = document.getElementById('copy-link');
+
+  if (btnCopyLink === null) {
+    return;
+  }
+
+  btnCopyLink.addEventListener('click', (e) => {
+    const target = e.target;
+
+    if (isLocked(target)) {
+      return;
+    }
+
+    // Copy URL to clipboard
+    navigator.clipboard.writeText(window.location.href).then(() => {
+      const defaultTitle = target.getAttribute(ATTR_TITLE_ORIGIN);
+      const succeedTitle = target.getAttribute(ATTR_TITLE_SUCCEED);
+
+      // Switch tooltip title
+      target.setAttribute(ATTR_TITLE_ORIGIN, succeedTitle);
+      Tooltip.getInstance(target).show();
+
+      lock(target);
+
+      setTimeout(() => {
+        target.setAttribute(ATTR_TITLE_ORIGIN, defaultTitle);
+        unlock(target);
+      }, TIMEOUT);
+    });
+  });
+
+  btnCopyLink.addEventListener('mouseleave', (e) => {
+    Tooltip.getInstance(e.target).hide();
+  });
+}
+
+export function initClipboard() {
+  setCodeClipboard();
+  setLinkClipboard();
+}

assets/js/modules/components/img-loading.js

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+/**
+ * Setting up image lazy loading and LQIP switching
+ */
+
+const ATTR_DATA_SRC = 'data-src';
+const ATTR_DATA_LQIP = 'data-lqip';
+
+const cover = {
+  SHIMMER: 'shimmer',
+  BLUR: 'blur'
+};
+
+function removeCover(clzss) {
+  this.parentElement.classList.remove(clzss);
+}
+
+function handleImage() {
+  if (!this.complete) {
+    return;
+  }
+
+  if (this.hasAttribute(ATTR_DATA_LQIP)) {
+    removeCover.call(this, cover.BLUR);
+  } else {
+    removeCover.call(this, cover.SHIMMER);
+  }
+}
+
+/**
+ * Switches the LQIP with the real image URL.
+ */
+function switchLQIP() {
+  const src = this.getAttribute(ATTR_DATA_SRC);
+  this.setAttribute('src', encodeURI(src));
+  this.removeAttribute(ATTR_DATA_SRC);
+}
+
+export function loadImg() {
+  const images = document.querySelectorAll('article img');
+
+  if (images.length === 0) {
+    return;
+  }
+
+  images.forEach((img) => {
+    img.addEventListener('load', handleImage);
+  });
+
+  // Images loaded from the browser cache do not trigger the 'load' event
+  document.querySelectorAll('article img[loading="lazy"]').forEach((img) => {
+    if (img.complete) {
+      removeCover.call(img, cover.SHIMMER);
+    }
+  });
+
+  // LQIPs set by the data URI or WebP will not trigger the 'load' event,
+  // so manually convert the URI to the URL of a high-resolution image.
+  const lqips = document.querySelectorAll(
+    `article img[${ATTR_DATA_LQIP}="true"]`
+  );
+
+  if (lqips.length) {
+    lqips.forEach((lqip) => {
+      switchLQIP.call(lqip);
+    });
+  }
+}

assets/js/modules/components/img-popup.js

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+/**
+ * Set up image popup
+ *
+ * Dependencies: https://github.com/biati-digital/glightbox
+ */
+
+const lightImages = '.popup:not(.dark)';
+const darkImages = '.popup:not(.light)';
+let selector = lightImages;
+
+function updateImages(current, reverse) {
+  if (selector === lightImages) {
+    selector = darkImages;
+  } else {
+    selector = lightImages;
+  }
+
+  if (reverse === null) {
+    reverse = GLightbox({ selector: `${selector}` });
+  }
+
+  [current, reverse] = [reverse, current];
+}
+
+export function imgPopup() {
+  if (document.querySelector('.popup') === null) {
+    return;
+  }
+
+  const hasDualImages = !(
+    document.querySelector('.popup.light') === null &&
+    document.querySelector('.popup.dark') === null
+  );
+
+  if (Theme.visualState === Theme.DARK) {
+    selector = darkImages;
+  }
+
+  let current = GLightbox({ selector: `${selector}` });
+
+  if (hasDualImages && Theme.switchable) {
+    let reverse = null;
+
+    window.addEventListener('message', (event) => {
+      if (event.source === window && event.data && event.data.id === Theme.ID) {
+        updateImages(current, reverse);
+      }
+    });
+  }
+}

assets/js/modules/components/locale-datetime.js

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+/**
+ * Update month/day to locale datetime
+ *
+ * Requirement: <https://github.com/iamkun/dayjs>
+ */
+
+/* A tool for locale datetime */
+class LocaleHelper {
+  static get attrTimestamp() {
+    return 'data-ts';
+  }
+
+  static get attrDateFormat() {
+    return 'data-df';
+  }
+
+  static get locale() {
+    return document.documentElement.getAttribute('lang').substring(0, 2);
+  }
+
+  static getTimestamp(elem) {
+    return Number(elem.getAttribute(this.attrTimestamp)); // unix timestamp
+  }
+
+  static getDateFormat(elem) {
+    return elem.getAttribute(this.attrDateFormat);
+  }
+}
+
+export function initLocaleDatetime() {
+  dayjs.locale(LocaleHelper.locale);
+  dayjs.extend(window.dayjs_plugin_localizedFormat);
+
+  document
+    .querySelectorAll(`[${LocaleHelper.attrTimestamp}]`)
+    .forEach((elem) => {
+      const date = dayjs.unix(LocaleHelper.getTimestamp(elem));
+      const text = date.format(LocaleHelper.getDateFormat(elem));
+      elem.textContent = text;
+      elem.removeAttribute(LocaleHelper.attrTimestamp);
+      elem.removeAttribute(LocaleHelper.attrDateFormat);
+
+      // setup tooltips
+      if (
+        elem.hasAttribute('data-bs-toggle') &&
+        elem.getAttribute('data-bs-toggle') === 'tooltip'
+      ) {
+        // see: https://day.js.org/docs/en/display/format#list-of-localized-formats
+        const tooltipText = date.format('llll');
+        elem.setAttribute('data-bs-title', tooltipText);
+      }
+    });
+}

assets/js/modules/components/mermaid.js

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+/**
+ * Mermaid-js loader
+ */
+
+const MERMAID = 'mermaid';
+const themeMapper = Theme.getThemeMapper('default', 'dark');
+
+function refreshTheme(event) {
+  if (event.source === window && event.data && event.data.id === Theme.ID) {
+    // Re-render the SVG › <https://github.com/mermaid-js/mermaid/issues/311#issuecomment-332557344>
+    const mermaidList = document.getElementsByClassName(MERMAID);
+
+    [...mermaidList].forEach((elem) => {
+      const svgCode = elem.previousSibling.children.item(0).textContent;
+      elem.textContent = svgCode;
+      elem.removeAttribute('data-processed');
+    });
+
+    const newTheme = themeMapper[Theme.visualState];
+
+    mermaid.initialize({ theme: newTheme });
+    mermaid.init(null, `.${MERMAID}`);
+  }
+}
+
+function setNode(elem) {
+  const svgCode = elem.textContent;
+  const backup = elem.parentElement;
+  backup.classList.add('d-none');
+  // Create mermaid node
+  const mermaid = document.createElement('pre');
+  mermaid.classList.add(MERMAID);
+  const text = document.createTextNode(svgCode);
+  mermaid.appendChild(text);
+  backup.after(mermaid);
+}
+
+export function loadMermaid() {
+  if (
+    typeof mermaid === 'undefined' ||
+    typeof mermaid.initialize !== 'function'
+  ) {
+    return;
+  }
+
+  const initTheme = themeMapper[Theme.visualState];
+
+  let mermaidConf = {
+    theme: initTheme
+  };
+
+  const basicList = document.getElementsByClassName('language-mermaid');
+  [...basicList].forEach(setNode);
+
+  mermaid.initialize(mermaidConf);
+
+  if (Theme.switchable) {
+    window.addEventListener('message', refreshTheme);
+  }
+}

assets/js/modules/components/mode-toggle.js

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+/**
+ * Add listener for theme mode toggle
+ */
+
+const $toggle = document.getElementById('mode-toggle');
+
+export function modeWatcher() {
+  if (!$toggle) {
+    return;
+  }
+
+  $toggle.addEventListener('click', () => {
+    Theme.flip();
+  });
+}

assets/js/modules/components/search-display.js

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+/**
+ * This script make #search-result-wrapper switch to unload or shown automatically.
+ */
+
+const btnSbTrigger = document.getElementById('sidebar-trigger');
+const btnSearchTrigger = document.getElementById('search-trigger');
+const btnCancel = document.getElementById('search-cancel');
+const content = document.querySelectorAll('#main-wrapper>.container>.row');
+const topbarTitle = document.getElementById('topbar-title');
+const search = document.getElementById('search');
+const resultWrapper = document.getElementById('search-result-wrapper');
+const results = document.getElementById('search-results');
+const input = document.getElementById('search-input');
+const hints = document.getElementById('search-hints');
+
+// CSS class names
+const LOADED = 'd-block';
+const UNLOADED = 'd-none';
+const FOCUS = 'input-focus';
+const FLEX = 'd-flex';
+
+/* Actions in mobile screens (Sidebar hidden) */
+class MobileSearchBar {
+  static on() {
+    btnSbTrigger.classList.add(UNLOADED);
+    topbarTitle.classList.add(UNLOADED);
+    btnSearchTrigger.classList.add(UNLOADED);
+    search.classList.add(FLEX);
+    btnCancel.classList.add(LOADED);
+  }
+
+  static off() {
+    btnCancel.classList.remove(LOADED);
+    search.classList.remove(FLEX);
+    btnSbTrigger.classList.remove(UNLOADED);
+    topbarTitle.classList.remove(UNLOADED);
+    btnSearchTrigger.classList.remove(UNLOADED);
+  }
+}
+
+class ResultSwitch {
+  static resultVisible = false;
+
+  static on() {
+    if (!this.resultVisible) {
+      resultWrapper.classList.remove(UNLOADED);
+      content.forEach((el) => {
+        el.classList.add(UNLOADED);
+      });
+      this.resultVisible = true;
+    }
+  }
+
+  static off() {
+    if (this.resultVisible) {
+      results.innerHTML = '';
+
+      if (hints.classList.contains(UNLOADED)) {
+        hints.classList.remove(UNLOADED);
+      }
+
+      resultWrapper.classList.add(UNLOADED);
+      content.forEach((el) => {
+        el.classList.remove(UNLOADED);
+      });
+      input.textContent = '';
+      this.resultVisible = false;
+    }
+  }
+}
+
+function isMobileView() {
+  return btnCancel.classList.contains(LOADED);
+}
+
+export function displaySearch() {
+  btnSearchTrigger.addEventListener('click', () => {
+    MobileSearchBar.on();
+    ResultSwitch.on();
+    input.focus();
+  });
+
+  btnCancel.addEventListener('click', () => {
+    MobileSearchBar.off();
+    ResultSwitch.off();
+  });
+
+  input.addEventListener('focus', () => {
+    search.classList.add(FOCUS);
+  });
+
+  input.addEventListener('focusout', () => {
+    search.classList.remove(FOCUS);
+  });
+
+  input.addEventListener('input', () => {
+    if (input.value === '') {
+      if (isMobileView()) {
+        hints.classList.remove(UNLOADED);
+      } else {
+        ResultSwitch.off();
+      }
+    } else {
+      ResultSwitch.on();
+      if (isMobileView()) {
+        hints.classList.add(UNLOADED);
+      }
+    }
+  });
+}

assets/js/modules/components/toc.js

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+import { TocMobile as mobile } from './toc/toc-mobile';
+import { TocDesktop as desktop } from './toc/toc-desktop';
+
+const desktopMode = matchMedia('(min-width: 1200px)');
+
+function refresh(e) {
+  if (e.matches) {
+    if (mobile.popupOpened) {
+      mobile.hidePopup();
+    }
+
+    desktop.refresh();
+  } else {
+    mobile.refresh();
+  }
+}
+
+function init() {
+  if (document.querySelector('main>article[data-toc="true"]') === null) {
+    return;
+  }
+
+  // Avoid create multiple instances of Tocbot. Ref: <https://github.com/tscanlin/tocbot/issues/203>
+  if (desktopMode.matches) {
+    desktop.init();
+  } else {
+    mobile.init();
+  }
+
+  const $tocWrapper = document.getElementById('toc-wrapper');
+  $tocWrapper.classList.remove('invisible');
+
+  desktopMode.onchange = refresh;
+}
+
+export { init as initToc };

assets/js/modules/components/toc/toc-desktop.js

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+export class TocDesktop {
+  /* Tocbot options Ref: https://github.com/tscanlin/tocbot#usage */
+  static options = {
+    tocSelector: '#toc',
+    contentSelector: '.content',
+    ignoreSelector: '[data-toc-skip]',
+    headingSelector: 'h2, h3, h4',
+    orderedList: false,
+    scrollSmooth: false,
+    headingsOffset: 16 * 2 // 2rem
+  };
+
+  static refresh() {
+    tocbot.refresh(this.options);
+  }
+
+  static init() {
+    tocbot.init(this.options);
+  }
+}

assets/js/modules/components/toc/toc-mobile.js

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+/**
+ * TOC button, topbar and popup for mobile devices
+ */
+
+const $tocBar = document.getElementById('toc-bar');
+const $soloTrigger = document.getElementById('toc-solo-trigger');
+const $triggers = document.getElementsByClassName('toc-trigger');
+const $popup = document.getElementById('toc-popup');
+const $btnClose = document.getElementById('toc-popup-close');
+
+const SCROLL_LOCK = 'overflow-hidden';
+const CLOSING = 'closing';
+
+export class TocMobile {
+  static #invisible = true;
+  static #barHeight = 16 * 3; // 3rem
+
+  static options = {
+    tocSelector: '#toc-popup-content',
+    contentSelector: '.content',
+    ignoreSelector: '[data-toc-skip]',
+    headingSelector: 'h2, h3, h4',
+    orderedList: false,
+    scrollSmooth: false,
+    collapseDepth: 4,
+    headingsOffset: this.#barHeight
+  };
+
+  static initBar() {
+    const observer = new IntersectionObserver(
+      (entries) => {
+        entries.forEach((entry) => {
+          $tocBar.classList.toggle('invisible', entry.isIntersecting);
+        });
+      },
+      { rootMargin: `-${this.#barHeight}px 0px 0px 0px` }
+    );
+
+    observer.observe($soloTrigger);
+    this.#invisible = false;
+  }
+
+  static listenAnchors() {
+    const $anchors = document.getElementsByClassName('toc-link');
+    [...$anchors].forEach((anchor) => {
+      anchor.onclick = () => this.hidePopup();
+    });
+  }
+
+  static refresh() {
+    if (this.#invisible) {
+      this.initComponents();
+    }
+    tocbot.refresh(this.options);
+    this.listenAnchors();
+  }
+
+  static get popupOpened() {
+    return $popup.open;
+  }
+
+  static showPopup() {
+    this.lockScroll(true);
+    $popup.showModal();
+    const activeItem = $popup.querySelector('li.is-active-li');
+    activeItem.scrollIntoView({ block: 'center' });
+  }
+
+  static hidePopup() {
+    $popup.toggleAttribute(CLOSING);
+
+    $popup.addEventListener(
+      'animationend',
+      () => {
+        $popup.toggleAttribute(CLOSING);
+        $popup.close();
+      },
+      { once: true }
+    );
+
+    this.lockScroll(false);
+  }
+
+  static lockScroll(enable) {
+    document.documentElement.classList.toggle(SCROLL_LOCK, enable);
+    document.body.classList.toggle(SCROLL_LOCK, enable);
+  }
+
+  static clickBackdrop(event) {
+    if ($popup.hasAttribute(CLOSING)) {
+      return;
+    }
+
+    const rect = event.target.getBoundingClientRect();
+    if (
+      event.clientX < rect.left ||
+      event.clientX > rect.right ||
+      event.clientY < rect.top ||
+      event.clientY > rect.bottom
+    ) {
+      this.hidePopup();
+    }
+  }
+
+  static initComponents() {
+    this.initBar();
+
+    [...$triggers].forEach((trigger) => {
+      trigger.onclick = () => this.showPopup();
+    });
+
+    $popup.onclick = (e) => this.clickBackdrop(e);
+    $btnClose.onclick = () => this.hidePopup();
+    $popup.oncancel = (e) => {
+      e.preventDefault();
+      this.hidePopup();
+    };
+  }
+
+  static init() {
+    tocbot.init(this.options);
+    this.listenAnchors();
+    this.initComponents();
+  }
+}

assets/js/modules/components/tooltip-loader.js

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+import Tooltip from 'bootstrap/js/src/tooltip';
+
+export function loadTooptip() {
+  const tooltipTriggerList = document.querySelectorAll(
+    '[data-bs-toggle="tooltip"]'
+  );
+
+  [...tooltipTriggerList].map(
+    (tooltipTriggerEl) => new Tooltip(tooltipTriggerEl)
+  );
+}

assets/js/modules/layouts.js

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+export { basic } from './layouts/basic';
+export { initSidebar } from './layouts/sidebar';
+export { initTopbar } from './layouts/topbar';

assets/js/modules/layouts/basic.js

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+import { back2top, loadTooptip, modeWatcher } from '../components';
+
+export function basic() {
+  modeWatcher();
+  back2top();
+  loadTooptip();
+}

assets/js/modules/layouts/sidebar.js

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+const ATTR_DISPLAY = 'sidebar-display';
+const $sidebar = document.getElementById('sidebar');
+const $trigger = document.getElementById('sidebar-trigger');
+const $mask = document.getElementById('mask');
+
+class SidebarUtil {
+  static #isExpanded = false;
+
+  static toggle() {
+    this.#isExpanded = !this.#isExpanded;
+    document.body.toggleAttribute(ATTR_DISPLAY, this.#isExpanded);
+    $sidebar.classList.toggle('z-2', this.#isExpanded);
+    $mask.classList.toggle('d-none', !this.#isExpanded);
+  }
+}
+
+export function initSidebar() {
+  $trigger.onclick = $mask.onclick = () => SidebarUtil.toggle();
+}

assets/js/modules/layouts/topbar.js

@@ -0,0 +1,5 @@
+import { displaySearch } from '../components/search-display';
+
+export function initTopbar() {
+  displaySearch();
+}

assets/js/modules/theme.js

@@ -0,0 +1,138 @@
+/**
+ * Theme management class
+ *
+ * To reduce flickering during page load, this script should be loaded synchronously.
+ */
+class Theme {
+  static #modeKey = 'mode';
+  static #modeAttr = 'data-mode';
+  static #darkMedia = window.matchMedia('(prefers-color-scheme: dark)');
+  static switchable = !document.documentElement.hasAttribute(this.#modeAttr);
+
+  static get DARK() {
+    return 'dark';
+  }
+
+  static get LIGHT() {
+    return 'light';
+  }
+
+  /**
+   * @returns {string} Theme mode identifier
+   */
+  static get ID() {
+    return 'theme-mode';
+  }
+
+  /**
+   * Gets the current visual state of the theme.
+   *
+   * @returns {string} The current visual state, either the mode if it exists,
+   *                   or the system dark mode state ('dark' or 'light').
+   */
+  static get visualState() {
+    if (this.#hasMode) {
+      return this.#mode;
+    } else {
+      return this.#sysDark ? this.DARK : this.LIGHT;
+    }
+  }
+
+  static get #mode() {
+    return (
+      sessionStorage.getItem(this.#modeKey) ||
+      document.documentElement.getAttribute(this.#modeAttr)
+    );
+  }
+
+  static get #isDarkMode() {
+    return this.#mode === this.DARK;
+  }
+
+  static get #hasMode() {
+    return this.#mode !== null;
+  }
+
+  static get #sysDark() {
+    return this.#darkMedia.matches;
+  }
+
+  /**
+   * Maps theme modes to provided values
+   * @param {string} light Value for light mode
+   * @param {string} dark Value for dark mode
+   * @returns {Object} Mapped values
+   */
+  static getThemeMapper(light, dark) {
+    return {
+      [this.LIGHT]: light,
+      [this.DARK]: dark
+    };
+  }
+
+  /**
+   * Initializes the theme based on system preferences or stored mode
+   */
+  static init() {
+    if (!this.switchable) {
+      return;
+    }
+
+    this.#darkMedia.addEventListener('change', () => {
+      const lastMode = this.#mode;
+      this.#clearMode();
+
+      if (lastMode !== this.visualState) {
+        this.#notify();
+      }
+    });
+
+    if (!this.#hasMode) {
+      return;
+    }
+
+    if (this.#isDarkMode) {
+      this.#setDark();
+    } else {
+      this.#setLight();
+    }
+  }
+
+  /**
+   * Flips the current theme mode
+   */
+  static flip() {
+    if (this.#hasMode) {
+      this.#clearMode();
+    } else {
+      this.#sysDark ? this.#setLight() : this.#setDark();
+    }
+    this.#notify();
+  }
+
+  static #setDark() {
+    document.documentElement.setAttribute(this.#modeAttr, this.DARK);
+    sessionStorage.setItem(this.#modeKey, this.DARK);
+  }
+
+  static #setLight() {
+    document.documentElement.setAttribute(this.#modeAttr, this.LIGHT);
+    sessionStorage.setItem(this.#modeKey, this.LIGHT);
+  }
+
+  static #clearMode() {
+    document.documentElement.removeAttribute(this.#modeAttr);
+    sessionStorage.removeItem(this.#modeKey);
+  }
+
+  /**
+   * Notifies other plugins that the theme mode has changed
+   */
+  static #notify() {
+    window.postMessage({ id: this.ID }, '*');
+  }
+}
+
+Theme.init();
+
+export default Theme;