如何为下拉按钮选择定义两个值？

<select id="myDropdown">
  <option value="value1">Option 1</option>
  <option value="value2">Option 2</option>
</select>

document.getElementById("myDropdown").addEventListener("change", function() {
  var selectedValue = this.value;
  // 执行相关操作，根据selectedValue的值进行处理
});

import React, { useState } from 'react';

function Dropdown() {
  const [selectedValue, setSelectedValue] = useState("");

  const handleChange = (event) => {
    setSelectedValue(event.target.value);
    // 执行相关操作，根据selectedValue的值进行处理
  }

  return (
    <select value={selectedValue} onChange={handleChange}>
      <option value="value1">Option 1</option>
      <option value="value2">Option 2</option>
    </select>
  );
}

<form method="post" action="process.php">
  <select name="myDropdown">
    <option value="value1">Option 1</option>
    <option value="value2">Option 2</option>
  </select>
  <input type="submit" value="Submit">
</form>