与任何异步调用一样，返回它可能需要花费不确定的时间.一种干净的解决方案是简单地添加

As any async call, it may take an undeterminable amount of time to return. One clean solution would be to simply add a loading icon to your main.html. And after the iframe loads simply hide the loading icon.

它应该有助于改善用户体验，因为他们在单击图标后至少可以立即看到某些内容.

It should help with the user experience as they'll be able to see at least something right after clicking the icon.