js二级菜单 点击

<ul class="menu">
  <li>
    <a href="#">菜单1</a>
    <ul class="submenu">
      <li><a href="#">子菜单1-1</a></li>
      <li><a href="#">子菜单1-2</a></li>
    </ul>
  </li>
  <li>
    <a href="#">菜单2</a>
    <ul class="submenu">
      <li><a href="#">子菜单2-1</a></li>
      <li><a href="#">子菜单2-2</a></li>
    </ul>
  </li>
</ul>

.menu {
  list-style: none;
  padding: 0;
}

.menu > li {
  position: relative;
}

.menu > li > a {
  display: block;
  padding: 10px;
  text-decoration: none;
  color: #333;
}

.submenu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background-color: #fff;
  border: 1px solid #ccc;
  list-style: none;
  padding: 0;
  min-width: 150px;
}

.submenu li a {
  display: block;
  padding: 10px;
  text-decoration: none;
  color: #333;
}

.submenu li a:hover {
  background-color: #f0f0f0;
}

document.addEventListener('DOMContentLoaded', function() {
  const menuItems = document.querySelectorAll('.menu > li');

  menuItems.forEach(function(item) {
    item.addEventListener('click', function(event) {
      event.stopPropagation();
      const submenu = this.querySelector('.submenu');
      if (submenu) {
        submenu.style.display = submenu.style.display === 'block' ? 'none' : 'block';
      }
    });
  });

  // 点击页面其他地方时隐藏所有子菜单
  document.addEventListener('click', function() {
    const submenus = document.querySelectorAll('.submenu');
    submenus.forEach(function(submenu) {
      submenu.style.display = 'none';
    });
  });
});