如何使此弹出窗口仅在单击按钮时加载

<button id="openButton">点击打开弹出窗口</button>

<div id="popupWindow" style="display: none;">
  <!-- 弹出窗口的内容 -->
</div>

// 获取按钮和弹出窗口的引用
var openButton = document.getElementById("openButton");
var popupWindow = document.getElementById("popupWindow");

// 定义按钮的点击事件处理函数
openButton.addEventListener("click", function() {
  // 检查弹出窗口的显示状态
  if (popupWindow.style.display === "none") {
    // 如果弹出窗口是隐藏的，则显示弹出窗口
    popupWindow.style.display = "block";
  } else {
    // 如果弹出窗口是显示的，则隐藏弹出窗口
    popupWindow.style.display = "none";
  }
});

#popupWindow {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 400px;
  height: 200px;
  background-color: #fff;
  border: 1px solid #ccc;
  padding: 20px;
}