比较简单的异步加载JS文件的代码

<script>
function getJsFile(url, callBack){
var XH = window.XMLHttpRequest ? new XMLHttpRequest : new ActiveXObject('Msxml2.XMLHTTP');
XH.open('get',url,true);
XH.onreadystatechange = function(){
if(XH.readyState == 4 && XH.status == 200){
if(window.execScript) window.execScript(XH.responseText);
else eval.call(window, XH.responseText);
eval(callBack)();
}
}
XH.send('');
}
</script>

//test
<script>
function cb(){
alert(1);
abc(); //这个是在js9.js 中的
}
getJsFile('https://www.jb51.net/images/test.js,'cb');
</script>