Method 1
Lots of extensions can be added this way including Asynchronous inclusion and script deferring. Lots of ad networks and hi traffic sites use this approach.
<script type="text/javascript">
(function(){
var randomh=Math.random();
var e = document.getElementsByTagName("script")[0];
var d = document.createElement("script");
d.src = "//site.com/js.js?x="+randomh+"";
d.type = "text/javascript";
d.async = true;
d.defer = true;
e.parentNode.insertBefore(d,e);
})();
</script>
Method 2 (AJZane's comment)
Small and robust inclusion. You can see exactly where JavaScript is fired and it is less customisable (to the point) than Method 1.
<script>document.write("<script type='text/javascript' src='//site.com
/js.js?v=" + Date.now() + "'></script>");</script>
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…