js鼠标滑过下拉菜单

<div class="dropdown">
  <button class="dropbtn">Dropdown</button>
  <div class="dropdown-content">
    <a href="#">Link 1</a>
    <a href="#">Link 2</a>
    <a href="#">Link 3</a>
  </div>
</div>

.dropdown {
  position: relative;
  display: inline-block;
}

.dropbtn {
  background-color: #4CAF50;
  color: white;
  padding: 16px;
  font-size: 16px;
  border: none;
  cursor: pointer;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
}

.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

.dropdown-content a:hover {background-color: #f1f1f1}

document.addEventListener('DOMContentLoaded', function() {
  var dropdown = document.querySelector('.dropdown');
  var dropdownContent = document.querySelector('.dropdown-content');

  dropdown.addEventListener('mouseenter', function() {
    dropdownContent.style.display = 'block';
  });

  dropdown.addEventListener('mouseleave', function() {
    dropdownContent.style.display = 'none';
  });
});

document.addEventListener('DOMContentLoaded', function() {
  var dropdown = document.querySelector('.dropdown');
  var dropdownContent = document.querySelector('.dropdown-content');

  dropdown.addEventListener('touchstart', function() {
    dropdownContent.style.display = dropdownContent.style.display === 'block' ? 'none' : 'block';
  });
});