异步加载google-analytics,用户看不到loading等待效果

如果script代码中，直接放入google-analytics代码，那么中国大陆的用户页面会显示loading转圈30s.
解决方法：

  function ga_async_load(fun){         if (window.attachEvent){             window.attachEvent('onload', fun);         }else{             window.addEventListener('load', fun, false);         }    }    ga_async_load( function(){        var s = document.createElement('script');        s.type = 'text/javascript';        s.async = true; //js下载之后立刻动作//       s.defer = true; //浏览器html parse后动作        s.innerHTML = "(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');ga('xxx', 'xxxx', 'xxx');ga('xxx', 'xxx');";        document.body.appendChild(s);    });