UI 组件中等

Keyboard Navigable Menu

Menu component fully navigable by keyboard using arrow keys, Home, End and type-ahead search following WAI-ARIA menu pattern.

在 Lab 中打开

vanilla-js

目标: JS HTML

代码

*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: #0a0a0a;
  color: #e5e5e5;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 2rem 1rem;
}

@media (min-width: 480px) {
  body {
    padding: 3rem 1.5rem;
  }
}

.demo-wrapper {
  width: 100%;
  max-width: 720px;
}

.demo-title {
  font-size: clamp(1.25rem, 5vw, 1.75rem);
  font-weight: 700;
  color: #f5f5f5;
  margin-bottom: 0.375rem;
}

.demo-subtitle {
  font-size: 0.9rem;
  color: #888;
  margin-bottom: 2.5rem;
  line-height: 1.5;
}

/* ── Menubar ──────────────────────────────────────── */

.menubar-container {
  position: relative;
  margin-bottom: 2rem;
  overflow-x: auto;
  /* smooth scrolling on iOS */
  -webkit-overflow-scrolling: touch;
  /* hide scrollbar but keep functionality */
  scrollbar-width: none;
}

.menubar-container::-webkit-scrollbar {
  display: none;
}

.menubar {
  display: flex;
  list-style: none;
  background: #161616;
  border: 1px solid #262626;
  border-radius: 10px;
  padding: 4px;
  gap: 2px;
  width: max-content;
  min-width: 100%;
}

.menubar-item {
  position: relative;
}

.menubar-button {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  background: transparent;
  border: none;
  border-radius: 7px;
  color: #b0b0b0;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
  white-space: nowrap;
}

.menubar-button:hover {
  background: #222;
  color: #e5e5e5;
}

.menubar-button:focus-visible {
  outline: 2px solid #6366f1;
  outline-offset: -2px;
  background: #1e1e2e;
  color: #f5f5f5;
}

.menubar-button[aria-expanded="true"] {
  background: #1e1e2e;
  color: #f5f5f5;
}

.menubar-button[aria-expanded="true"] .chevron {
  transform: rotate(180deg);
}

.chevron {
  transition: transform 0.2s ease;
  flex-shrink: 0;
}

/* ── Submenu ─────────────────────────────────────── */

.submenu {
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  list-style: none;
  background: #161616;
  border: 1px solid #2a2a2a;
  border-radius: 10px;
  padding: 4px;
  min-width: 200px;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: opacity 0.15s, transform 0.15s, visibility 0.15s;
  z-index: 100;
}

.submenu.open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.submenu-item {
  padding: 8px 14px;
  border-radius: 7px;
  font-size: 0.85rem;
  color: #c0c0c0;
  cursor: pointer;
  transition: background 0.12s, color 0.12s;
  white-space: nowrap;
}

.submenu-item:hover {
  background: #222;
  color: #f5f5f5;
}

.submenu-item:focus-visible,
.submenu-item.focused {
  outline: none;
  background: #2d2d5e;
  color: #f5f5f5;
}

.submenu-separator {
  height: 1px;
  background: #262626;
  margin: 4px 8px;
}

/* ── Action Log ──────────────────────────────────── */

.action-log {
  background: #111;
  border: 1px solid #222;
  border-radius: 10px;
  padding: 16px 20px;
  min-height: 60px;
  margin-bottom: 2.5rem;
  font-size: 0.85rem;
  color: #888;
}

.action-log .log-entry {
  color: #a5b4fc;
  padding: 2px 0;
}

.action-log .log-entry::before {
  content: "\25B8  ";
  color: #6366f1;
}

.log-placeholder {
  color: #555;
  font-style: italic;
}

/* ── Keyboard Guide ──────────────────────────────── */

.keyboard-guide {
  background: #111;
  border: 1px solid #222;
  border-radius: 12px;
  padding: 16px;
}

@media (min-width: 480px) {
  .keyboard-guide {
    padding: 24px;
  }
}

.guide-title {
  font-size: 1rem;
  font-weight: 600;
  color: #d4d4d4;
  margin-bottom: 16px;
}

.guide-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
}

@media (min-width: 500px) {
  .guide-grid {
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 12px;
  }
}

.guide-item {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
  font-size: 0.85rem;
  color: #999;
}

.guide-item span {
  flex: 1;
  min-width: 0;
}

kbd {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 26px;
  height: 26px;
  padding: 0 7px;
  background: #1a1a1a;
  border: 1px solid #333;
  border-bottom-width: 2px;
  border-radius: 5px;
  font-family: inherit;
  font-size: 0.75rem;
  font-weight: 600;
  color: #ccc;
  line-height: 1;
}

(() => {
  const menubar = document.getElementById("menubar");
  const actionLog = document.getElementById("actionLog");
  const menubarButtons = [...menubar.querySelectorAll(".menubar-button")];

  let currentMenubarIndex = 0;
  let typeAheadBuffer = "";
  let typeAheadTimer = null;

  /* ── Helpers ──────────────────────────────────────── */

  function getSubmenu(button) {
    return button.parentElement.querySelector(".submenu");
  }

  function getMenuItems(submenu) {
    return [...submenu.querySelectorAll('[role="menuitem"]')];
  }

  function openSubmenu(button) {
    // Close all others first
    menubarButtons.forEach((btn) => closeSubmenu(btn));
    const submenu = getSubmenu(button);
    button.setAttribute("aria-expanded", "true");
    submenu.classList.add("open");
  }

  function closeSubmenu(button) {
    const submenu = getSubmenu(button);
    button.setAttribute("aria-expanded", "false");
    submenu.classList.remove("open");
    // Remove focused class from all items
    getMenuItems(submenu).forEach((item) => item.classList.remove("focused"));
  }

  function closeAllSubmenus() {
    menubarButtons.forEach((btn) => closeSubmenu(btn));
  }

  function isSubmenuOpen(button) {
    return button.getAttribute("aria-expanded") === "true";
  }

  function focusMenubarItem(index) {
    menubarButtons[currentMenubarIndex].setAttribute("tabindex", "-1");
    currentMenubarIndex = index;
    menubarButtons[currentMenubarIndex].setAttribute("tabindex", "0");
    menubarButtons[currentMenubarIndex].focus();
  }

  function focusSubmenuItem(submenu, index) {
    const items = getMenuItems(submenu);
    items.forEach((item) => item.classList.remove("focused"));
    if (index >= 0 && index < items.length) {
      items[index].classList.add("focused");
      items[index].focus();
    }
  }

  function getFocusedSubmenuIndex(submenu) {
    const items = getMenuItems(submenu);
    return items.findIndex((item) => item.classList.contains("focused"));
  }

  function logAction(text) {
    const placeholder = actionLog.querySelector(".log-placeholder");
    if (placeholder) placeholder.remove();

    const entry = document.createElement("p");
    entry.className = "log-entry";
    entry.textContent = text;
    actionLog.prepend(entry);

    // Keep only last 5 entries
    const entries = actionLog.querySelectorAll(".log-entry");
    if (entries.length > 5) {
      entries[entries.length - 1].remove();
    }
  }

  /* ── Menubar keyboard navigation ─────────────────── */

  menubarButtons.forEach((button, index) => {
    // Click to open/close
    button.addEventListener("click", () => {
      if (isSubmenuOpen(button)) {
        closeSubmenu(button);
      } else {
        openSubmenu(button);
        const submenu = getSubmenu(button);
        focusSubmenuItem(submenu, 0);
      }
      focusMenubarItem(index);
    });

    // Keyboard on menubar buttons
    button.addEventListener("keydown", (e) => {
      switch (e.key) {
        case "ArrowRight": {
          e.preventDefault();
          const wasOpen = isSubmenuOpen(button);
          closeAllSubmenus();
          const next = (index + 1) % menubarButtons.length;
          focusMenubarItem(next);
          if (wasOpen) {
            openSubmenu(menubarButtons[next]);
            focusSubmenuItem(getSubmenu(menubarButtons[next]), 0);
          }
          break;
        }
        case "ArrowLeft": {
          e.preventDefault();
          const wasOpen = isSubmenuOpen(button);
          closeAllSubmenus();
          const prev = (index - 1 + menubarButtons.length) % menubarButtons.length;
          focusMenubarItem(prev);
          if (wasOpen) {
            openSubmenu(menubarButtons[prev]);
            focusSubmenuItem(getSubmenu(menubarButtons[prev]), 0);
          }
          break;
        }
        case "ArrowDown":
        case "Enter":
        case " ": {
          e.preventDefault();
          openSubmenu(button);
          const submenu = getSubmenu(button);
          focusSubmenuItem(submenu, 0);
          break;
        }
        case "Escape": {
          e.preventDefault();
          closeAllSubmenus();
          break;
        }
        case "Home": {
          e.preventDefault();
          closeAllSubmenus();
          focusMenubarItem(0);
          break;
        }
        case "End": {
          e.preventDefault();
          closeAllSubmenus();
          focusMenubarItem(menubarButtons.length - 1);
          break;
        }
      }
    });
  });

  /* ── Submenu keyboard navigation ─────────────────── */

  menubarButtons.forEach((button, menuIndex) => {
    const submenu = getSubmenu(button);
    const items = getMenuItems(submenu);

    items.forEach((item) => {
      item.addEventListener("keydown", (e) => {
        const currentIndex = getFocusedSubmenuIndex(submenu);
        const allItems = getMenuItems(submenu);

        switch (e.key) {
          case "ArrowDown": {
            e.preventDefault();
            let next = currentIndex + 1;
            // Skip separators
            while (next < allItems.length && allItems[next].getAttribute("role") === "separator") {
              next++;
            }
            if (next < allItems.length) {
              focusSubmenuItem(submenu, next);
            }
            break;
          }
          case "ArrowUp": {
            e.preventDefault();
            let prev = currentIndex - 1;
            while (prev >= 0 && allItems[prev].getAttribute("role") === "separator") {
              prev--;
            }
            if (prev >= 0) {
              focusSubmenuItem(submenu, prev);
            }
            break;
          }
          case "ArrowRight": {
            e.preventDefault();
            closeSubmenu(button);
            const nextMenu = (menuIndex + 1) % menubarButtons.length;
            focusMenubarItem(nextMenu);
            openSubmenu(menubarButtons[nextMenu]);
            focusSubmenuItem(getSubmenu(menubarButtons[nextMenu]), 0);
            break;
          }
          case "ArrowLeft": {
            e.preventDefault();
            closeSubmenu(button);
            const prevMenu = (menuIndex - 1 + menubarButtons.length) % menubarButtons.length;
            focusMenubarItem(prevMenu);
            openSubmenu(menubarButtons[prevMenu]);
            focusSubmenuItem(getSubmenu(menubarButtons[prevMenu]), 0);
            break;
          }
          case "Home": {
            e.preventDefault();
            focusSubmenuItem(submenu, 0);
            break;
          }
          case "End": {
            e.preventDefault();
            focusSubmenuItem(submenu, allItems.length - 1);
            break;
          }
          case "Enter":
          case " ": {
            e.preventDefault();
            logAction(`Activated: ${item.textContent.trim()}`);
            closeSubmenu(button);
            focusMenubarItem(menuIndex);
            break;
          }
          case "Escape": {
            e.preventDefault();
            closeSubmenu(button);
            focusMenubarItem(menuIndex);
            break;
          }
          case "Tab": {
            closeAllSubmenus();
            break;
          }
          default: {
            // Type-ahead: single character search
            if (e.key.length === 1 && /[a-zA-Z]/.test(e.key)) {
              e.preventDefault();
              typeAheadBuffer += e.key.toLowerCase();
              clearTimeout(typeAheadTimer);
              typeAheadTimer = setTimeout(() => {
                typeAheadBuffer = "";
              }, 500);

              const match = allItems.findIndex((el, i) => {
                if (el.getAttribute("role") === "separator") return false;
                return el.textContent.trim().toLowerCase().startsWith(typeAheadBuffer);
              });

              if (match !== -1) {
                focusSubmenuItem(submenu, match);
              }
            }
            break;
          }
        }
      });

      // Click on submenu item
      item.addEventListener("click", () => {
        if (item.getAttribute("role") === "separator") return;
        logAction(`Activated: ${item.textContent.trim()}`);
        closeSubmenu(button);
        focusMenubarItem(menuIndex);
      });
    });
  });

  /* ── Click outside to close ──────────────────────── */

  document.addEventListener("click", (e) => {
    if (!menubar.contains(e.target)) {
      closeAllSubmenus();
    }
  });
})();

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>Keyboard Navigable Menu</title>
  <link rel="stylesheet" href="style.css" />
</head>
<body>

  <div class="demo-wrapper">
    <h1 class="demo-title">Keyboard Navigable Menu</h1>
    <p class="demo-subtitle">Full WAI-ARIA menubar pattern with arrow keys, Home/End, Escape, and type-ahead search</p>

    <nav class="menubar-container" aria-label="Application menu">
      <ul role="menubar" class="menubar" id="menubar">

        <li role="none" class="menubar-item">
          <button role="menuitem" aria-haspopup="true" aria-expanded="false" class="menubar-button" tabindex="0">
            File
            <svg class="chevron" aria-hidden="true" width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5"><path d="m6 9 6 6 6-6"/></svg>
          </button>
          <ul role="menu" class="submenu" aria-label="File">
            <li role="menuitem" class="submenu-item" tabindex="-1">New File</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">New Window</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Open File&hellip;</li>
            <li role="separator" class="submenu-separator"></li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Save</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Save As&hellip;</li>
          </ul>
        </li>

        <li role="none" class="menubar-item">
          <button role="menuitem" aria-haspopup="true" aria-expanded="false" class="menubar-button" tabindex="-1">
            Edit
            <svg class="chevron" aria-hidden="true" width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5"><path d="m6 9 6 6 6-6"/></svg>
          </button>
          <ul role="menu" class="submenu" aria-label="Edit">
            <li role="menuitem" class="submenu-item" tabindex="-1">Undo</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Redo</li>
            <li role="separator" class="submenu-separator"></li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Cut</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Copy</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Paste</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Delete</li>
          </ul>
        </li>

        <li role="none" class="menubar-item">
          <button role="menuitem" aria-haspopup="true" aria-expanded="false" class="menubar-button" tabindex="-1">
            View
            <svg class="chevron" aria-hidden="true" width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5"><path d="m6 9 6 6 6-6"/></svg>
          </button>
          <ul role="menu" class="submenu" aria-label="View">
            <li role="menuitem" class="submenu-item" tabindex="-1">Zoom In</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Zoom Out</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Reset Zoom</li>
            <li role="separator" class="submenu-separator"></li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Toggle Sidebar</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Toggle Terminal</li>
          </ul>
        </li>

        <li role="none" class="menubar-item">
          <button role="menuitem" aria-haspopup="true" aria-expanded="false" class="menubar-button" tabindex="-1">
            Help
            <svg class="chevron" aria-hidden="true" width="12" height="12" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5"><path d="m6 9 6 6 6-6"/></svg>
          </button>
          <ul role="menu" class="submenu" aria-label="Help">
            <li role="menuitem" class="submenu-item" tabindex="-1">Documentation</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Release Notes</li>
            <li role="menuitem" class="submenu-item" tabindex="-1">Report Issue</li>
            <li role="separator" class="submenu-separator"></li>
            <li role="menuitem" class="submenu-item" tabindex="-1">About</li>
          </ul>
        </li>

      </ul>
    </nav>

    <div class="action-log" id="actionLog" aria-live="polite">
      <p class="log-placeholder">Select a menu item to see it logged here&hellip;</p>
    </div>

    <section class="keyboard-guide">
      <h2 class="guide-title">Keyboard Guide</h2>
      <div class="guide-grid">
        <div class="guide-item">
          <kbd>&larr;</kbd> <kbd>&rarr;</kbd>
          <span>Move between menubar items</span>
        </div>
        <div class="guide-item">
          <kbd>&darr;</kbd> <kbd>&uarr;</kbd>
          <span>Navigate within a dropdown</span>
        </div>
        <div class="guide-item">
          <kbd>Enter</kbd> / <kbd>Space</kbd>
          <span>Open dropdown or activate item</span>
        </div>
        <div class="guide-item">
          <kbd>Escape</kbd>
          <span>Close dropdown, return to menubar</span>
        </div>
        <div class="guide-item">
          <kbd>Home</kbd> / <kbd>End</kbd>
          <span>Jump to first / last item</span>
        </div>
        <div class="guide-item">
          <kbd>A</kbd>&ndash;<kbd>Z</kbd>
          <span>Type-ahead: jump to matching item</span>
        </div>
      </div>
    </section>
  </div>

  <script src="script.js"></script>
</body>
</html>

A fully accessible horizontal menubar with dropdown submenus implementing the complete WAI-ARIA menu keyboard pattern. Supports arrow key navigation, Home/End jumps, Escape to close, and type-ahead character search for rapid item selection.