js动态引入JS文件

<script type="text/javascript">
	function loadJS(path){
	    var oHead = document.getElementsByTagName('HEAD').item(0);
	    var oScript= document.createElement("script");
	    oScript.type = "text/javascript";
	    oScript.src=path;
	    oHead.appendChild( oScript); 
	}
	/** IE8浏览器需要添加canvas支持 */
	function lessIE8(){
		if(!+[1,]){// 万恶的IE浏览器！
			try{
				var Sys = {};
				var ua = navigator.userAgent.toLowerCase();
				var s;
				(s = ua.match(/msie ([\d.]+)/)) ? Sys.ie = s[1] :
				(s = ua.match(/firefox\/([\d.]+)/)) ? Sys.firefox = s[1] :
				(s = ua.match(/chrome\/([\d.]+)/)) ? Sys.chrome = s[1] :
				(s = ua.match(/opera.([\d.]+)/)) ? Sys.opera = s[1] :
				(s = ua.match(/version\/([\d.]+).*safari/)) ? Sys.safari = s[1] : 0;

				if(Sys.ie) document.getElementById('browserVersion').innerText= "IE "+Sys.ie;
				if(Sys.firefox) document.getElementById('browserVersion').innerText= "FireFox "+Sys.firefox;
				if(Sys.chrome) document.getElementById('browserVersion').innerText= "Chrome "+Sys.chrome;
				if(Sys.opera) document.getElementById('browserVersion').innerText= "Opera "+Sys.opera;
				if(Sys.safari) document.getElementById('browserVersion').innerText= "Safari "+Sys.safari;
				return (parseInt(Sys.ie)< 9); // 更万恶的低版本IE浏览器！
			}catch(e){
				return false;// 默认支持HTML5
			}
		}
	}
	//if(lessIE8()) loadJS("admin-ROOT/js/chart/excanvas.compiled.js");
</script>