如何在刷新页面后保留复选框并保留会话中的值

<form>
  <input type="checkbox" name="option1" value="value1" checked>选项1<br>
  <input type="checkbox" name="option2" value="value2">选项2<br>
  <input type="checkbox" name="option3" value="value3">选项3<br>
  <input type="submit" value="提交">
</form>

<?php
session_start();

if ($_SERVER["REQUEST_METHOD"] == "POST") {
  $_SESSION["option1"] = isset($_POST["option1"]) ? $_POST["option1"] : "";
  $_SESSION["option2"] = isset($_POST["option2"]) ? $_POST["option2"] : "";
  $_SESSION["option3"] = isset($_POST["option3"]) ? $_POST["option3"] : "";
}
?>

document.addEventListener("DOMContentLoaded", function() {
  var option1 = "<?php echo isset($_SESSION['option1']) ? $_SESSION['option1'] : ''; ?>";
  var option2 = "<?php echo isset($_SESSION['option2']) ? $_SESSION['option2'] : ''; ?>";
  var option3 = "<?php echo isset($_SESSION['option3']) ? $_SESSION['option3'] : ''; ?>";

  document.getElementsByName("option1")[0].checked = option1 === "value1";
  document.getElementsByName("option2")[0].checked = option2 === "value2";
  document.getElementsByName("option3")[0].checked = option3 === "value3";
});