layui弹出层无法关闭

<link rel="stylesheet" href="https://cdn.staticfile.org/layui/2.5.6/css/layui.css">
<script src="https://cdn.staticfile.org/layui/2.5.6/layui.js"></script>

<button id="openButton">打开弹出层</button>

<script>
layui.use('layer', function(){
  var layer = layui.layer;

  // 给按钮添加点击事件
  document.getElementById('openButton').onclick = function() {
    // 使用layer.open打开弹出层
    var index = layer.open({
      type: 2,
      content: '弹出层的页面路径'
    });
  }

  // 在弹出层的页面中给关闭按钮添加点击事件
  document.getElementById('closeButton').onclick = function() {
    // 获取父窗口的layer对象和弹出层的index
    var index = parent.layer.getFrameIndex(window.name);
    // 关闭弹出层
    parent.layer.close(index);
  }
});
</script>

<button id="closeButton">关闭弹出层</button>