切换和取消切换下拉菜单的外观

<button id="toggleBtn">切换下拉菜单</button>
<button id="cancelBtn">取消切换下拉菜单</button>
<ul id="dropdownMenu" class="dropdown-menu">
  <li>选项1</li>
  <li>选项2</li>
  <li>选项3</li>
</ul>

.dropdown-menu {
  display: none;
}

.dropdown-menu.show {
  display: block;
}

var toggleBtn = document.getElementById('toggleBtn');
var cancelBtn = document.getElementById('cancelBtn');
var dropdownMenu = document.getElementById('dropdownMenu');

toggleBtn.addEventListener('click', function() {
  dropdownMenu.classList.toggle('show');
});

cancelBtn.addEventListener('click', function() {
  dropdownMenu.classList.remove('show');
});