如何在刷新后保存状态按钮(更改类名)？

<button id="saveBtn" class="default">保存状态</button>

window.onload = function() {
  var saveBtn = document.getElementById("saveBtn");
  var savedState = localStorage.getItem("btnState");

  if (savedState === "active") {
    saveBtn.classList.add("active");
  } else {
    saveBtn.classList.remove("active");
  }
}

var saveBtn = document.getElementById("saveBtn");

saveBtn.addEventListener("click", function() {
  if (saveBtn.classList.contains("active")) {
    saveBtn.classList.remove("active");
    localStorage.setItem("btnState", "inactive");
  } else {
    saveBtn.classList.add("active");
    localStorage.setItem("btnState", "active");
  }
});

.default {
  background-color: gray;
  color: white;
}

.active {
  background-color: green;
  color: white;
}