选择上的下拉按钮禁用一些第二个下拉选项

<select id="firstDropdown" onchange="disableOptions()">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

<select id="secondDropdown">
  <option value="optionA">Option A</option>
  <option value="optionB">Option B</option>
  <option value="optionC">Option C</option>
</select>

<script>
function disableOptions() {
  var firstDropdown = document.getElementById("firstDropdown");
  var secondDropdown = document.getElementById("secondDropdown");
  
  // 获取第一个下拉选项的值
  var selectedValue = firstDropdown.value;
  
  // 根据第一个下拉选项的值禁用或启用第二个下拉选项
  if (selectedValue === "option1") {
    secondDropdown.options[0].disabled = true;
    secondDropdown.options[1].disabled = false;
    secondDropdown.options[2].disabled = false;
  } else if (selectedValue === "option2") {
    secondDropdown.options[0].disabled = false;
    secondDropdown.options[1].disabled = true;
    secondDropdown.options[2].disabled = false;
  } else if (selectedValue === "option3") {
    secondDropdown.options[0].disabled = false;
    secondDropdown.options[1].disabled = false;
    secondDropdown.options[2].disabled = true;
  }
}
</script>