例如,google+ 给出了以下代码:
<!-- Place this tag after the last +1 button tag. -->
<script type="text/javascript">
(function() {
var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true;
po.src = 'https://apis.google.com/js/plusone.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s);
})();
</script>
但为什么不只是这样:
<script async src="https://apis.google.com/js/plusone.js"></script>