使用JavaScript获取所选选项的值

var selectElement = document.getElementById("mySelect");

var selectedValue = selectElement.value;

<select id="mySelect">
  <option value="option1">选项1</option>
  <option value="option2">选项2</option>
  <option value="option3">选项3</option>
</select>

<script>
  var selectElement = document.getElementById("mySelect");
  var selectedValue = selectElement.value;
  console.log("所选选项的值为：" + selectedValue);
</script>