更改一个select，其他select都是更改

<select id="select1">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

<select id="select2">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

<select id="select3">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

// 获取select元素
var select1 = document.getElementById('select1');
var select2 = document.getElementById('select2');
var select3 = document.getElementById('select3');

// 监听select1的change事件
select1.addEventListener('change', function() {
  // 获取select1当前选中的值
  var selectedValue = select1.value;

  // 根据选中的值修改其他select元素的选项
  if (selectedValue === 'option1') {
    // 修改select2的选项
    select2.innerHTML = `
      <option value="option4">Option 4</option>
      <option value="option5">Option 5</option>
      <option value="option6">Option 6</option>
    `;
    
    // 修改select3的选项
    select3.innerHTML = `
      <option value="option7">Option 7</option>
      <option value="option8">Option 8</option>
      <option value="option9">Option 9</option>
    `;
  } else if (selectedValue === 'option2') {
    // 修改select2的选项
    select2.innerHTML = `
      <option value="option10">Option 10</option>
      <option value="option11">Option 11</option>
      <option value="option12">Option 12</option>
    `;
    
    // 修改select3的选项
    select3.innerHTML = `
      <option value="option13">Option 13</option>
      <option value="option14">Option 14</option>
      <option value="option15">Option 15</option>
    `;
  } else if (selectedValue === 'option3') {
    // 修改select2的选项
    select2.innerHTML = `
      <option value="option16">Option 16</option>
      <option value="option17">Option 17</option>
      <option value="option18">Option 18</option>
    `;
    
    // 修改select3的选项
    select3.innerHTML = `
      <option value="option19">Option 19</option>
      <option value="option20">Option 20</option>
      <option value="option21">Option 21</option>
    `;
  }
});