异步加载js不能使用document.write

<script>
var _hmt = _hmt || [];
(function() {
var hm = document.createElement("script");
hm.src = "https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js";
var s = document.getElementsByTagName("script")[0];
s.parentNode.insertBefore(hm, s);
})();
</script>