标识哪个select提交了表单

<form id="myForm" onsubmit="submitForm(event)">
  <select id="select1">
    <option value="option1">Option 1</option>
    <option value="option2">Option 2</option>
  </select>
  
  <select id="select2">
    <option value="option3">Option 3</option>
    <option value="option4">Option 4</option>
  </select>
  
  <button type="submit">Submit</button>
</form>

<script>
function submitForm(event) {
  event.preventDefault(); // 阻止表单默认提交行为
  
  var select1 = document.getElementById("select1");
  var select2 = document.getElementById("select2");
  
  if (select1.value !== "") {
    // select1提交了表单
    console.log("select1提交了表单");
    // 执行相关操作...
  } else if (select2.value !== "") {
    // select2提交了表单
    console.log("select2提交了表单");
    // 执行相关操作...
  }
}
</script>

<form action="submit.php" method="post">
  <select name="select">
    <option value="option1">Option 1</option>
    <option value="option2">Option 2</option>
  </select>
  
  <select name="select">
    <option value="option3">Option 3</option>
    <option value="option4">Option 4</option>
  </select>
  
  <button type="submit">Submit</button>
</form>

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $selectedOption = $_POST["select"];
  
  if ($selectedOption == "option1") {
    // select1提交了表单
    echo "select1提交了表单";
    // 执行相关操作...
  } else if ($selectedOption == "option2") {
    // select2提交了表单
    echo "select2提交了表单";
    // 执行相关操作...
  }
}
?>