如何在多个下拉列表中显示选中的值？

<select id="list1">
  <option value="value1">选项1</option>
  <option value="value2">选项2</option>
  <option value="value3">选项3</option>
</select>

<select id="list2">
  <option value="value4">选项4</option>
  <option value="value5">选项5</option>
  <option value="value6">选项6</option>
</select>

<select id="list3">
  <option value="value7">选项7</option>
  <option value="value8">选项8</option>
  <option value="value9">选项9</option>
</select>

// 获取下拉列表元素
var list1 = document.getElementById("list1");
var list2 = document.getElementById("list2");
var list3 = document.getElementById("list3");

// 监听下拉列表的变化事件
list1.addEventListener("change", updateSelectedValue);
list2.addEventListener("change", updateSelectedValue);
list3.addEventListener("change", updateSelectedValue);

// 更新选中的值
function updateSelectedValue() {
  var selectedValue1 = list1.options[list1.selectedIndex].value;
  var selectedValue2 = list2.options[list2.selectedIndex].value;
  var selectedValue3 = list3.options[list3.selectedIndex].value;

  // 将选中的值显示在其他地方，例如一个文本框或一个标签中
  var result = document.getElementById("result");
  result.textContent = "选中的值：" + selectedValue1 + "，" + selectedValue2 + "，" + selectedValue3;
}

<div id="result"></div>