select

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

<script>
  const select = document.getElementById("mySelect");
  console.log(select.value); // 当前选中的 value

  const selectedOption = select.options[select.selectedIndex];

  console.log(selectedOption.value); // 选中值
  console.log(selectedOption.text); // 显示文本
  console.log(selectedOption.index); // 下标

  select.addEventListener("change", function () {
    console.log(this.value);
  });
</script>