尝试从html>select发送值00,01,02，但在PHP值为0,1,2

<select id="mySelect">
  <option value="00">Option 00</option>
  <option value="01">Option 01</option>
  <option value="02">Option 02</option>
</select>

document.getElementById("mySelect").addEventListener("change", function() {
  var selectedValue = this.value;
  
  // 发送选中的值给后端的PHP脚本
  var xhr = new XMLHttpRequest();
  xhr.open("POST", "your_php_script.php", true);
  xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
      // 处理后端返回的响应
      var response = xhr.responseText;
      console.log(response);
    }
  };
  xhr.send("selectedValue=" + encodeURIComponent(selectedValue));
});

$selectedValue = $_POST['selectedValue'];

// 进行相应的处理
// ...

// 返回响应给前端
echo "处理成功";