js如何獲取下拉列表的id

// 假设下拉列表的ID为'mySelect'
var selectElement = document.getElementById('mySelect');
var id = selectElement.id;
console.log(id); // 输出: mySelect

<select id="mySelect">
  <option value="1">Option 1</option>
  <option value="2">Option 2</option>
</select>

<script>
document.getElementById('mySelect').addEventListener('change', function() {
  var id = this.id;
  console.log(id); // 输出: mySelect
});
</script>

var selectElements = document.getElementsByTagName('select');
for (var i = 0; i < selectElements.length; i++) {
  console.log(selectElements[i].id);
}

// 获取特定ID的下拉列表的ID
var id = $('#mySelect').attr('id');
console.log(id); // 输出: mySelect

// 或者监听事件
$('#mySelect').on('change', function() {
  var id = $(this).attr('id');
  console.log(id); // 输出: mySelect
});