js实现select效果

<div class="custom-select">
  <div class="selected-option">请选择</div>
  <ul class="options">
    <li>选项1</li>
    <li>选项2</li>
    <li>选项3</li>
  </ul>
</div>

.custom-select {
  position: relative;
  width: 200px;
}

.selected-option {
  border: 1px solid #ccc;
  padding: 10px;
  cursor: pointer;
}

.options {
  display: none;
  position: absolute;
  width: 100%;
  border: 1px solid #ccc;
  border-top: none;
  list-style-type: none;
  margin: 0;
  padding: 0;
  background-color: #fff;
}

.options li {
  padding: 10px;
  cursor: pointer;
}

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

document.addEventListener('DOMContentLoaded', function() {
  const customSelect = document.querySelector('.custom-select');
  const selectedOption = customSelect.querySelector('.selected-option');
  const options = customSelect.querySelector('.options');

  // 点击选择框时显示或隐藏选项列表
  selectedOption.addEventListener('click', function() {
    options.style.display = options.style.display === 'block' ? 'none' : 'block';
  });

  // 点击某个选项时更新选择框的文本并隐藏选项列表
  options.addEventListener('click', function(event) {
    if (event.target.tagName === 'LI') {
      selectedOption.textContent = event.target.textContent;
      options.style.display = 'none';
    }
  });

  // 点击文档其他地方时隐藏选项列表
  document.addEventListener('click', function(event) {
    if (!customSelect.contains(event.target)) {
      options.style.display = 'none';
    }
  });
});