下拉菜单中的if语句和php中的条件

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

<script>
  var dropdown = document.getElementById("myDropdown");
  dropdown.addEventListener("change", function() {
    var selectedOption = dropdown.value;
    if (selectedOption === "option1") {
      // 执行选项1的操作
    } else if (selectedOption === "option2") {
      // 执行选项2的操作
    } else if (selectedOption === "option3") {
      // 执行选项3的操作
    }
  });
</script>

$score = 80;

if ($score >= 90) {
  echo "优秀";
} elseif ($score >= 80) {
  echo "良好";
} elseif ($score >= 70) {
  echo "中等";
} else {
  echo "不及格";
}