获取<option>属性in<input>

<select id="mySelect">
  <option value="1">Option 1</option>
  <option value="2">Option 2</option>
  <option value="3">Option 3</option>
</select>

<script>
  var selectElement = document.getElementById("mySelect");
  var selectedOption = selectElement.options[selectElement.selectedIndex];
  var attributeValue = selectedOption.getAttribute("value");
  console.log(attributeValue);
</script>