html页面中异步加载js文件方法

<script type="text/javascript" async="async" src="http://thirdpart/js.js" ></script>

(function() {
function asyncLoad() {
var src = "http://thirdpart/js.js";
var urls = src.split(",");
var x = document.getElementsByTagName('body');
if(x && x[0]){
for (var i = 0; i < urls.length; i++) {
var s = document.createElement(&#39;script&#39;);
s.type = &#39;text/javascript&#39;;
s.async = true;
s.src = urls[i];
x[0].appendChild(s);
}
}
}
window.attachEvent ? window.attachEvent(&#39;onload&#39;, asyncLoad) :
window.addEventListener(&#39;load&#39;, asyncLoad, false);
})();