动态加载外部javascript文件的函数代码分享

(function (clover) { 
clover.loadScript = function loadScript(url, callback) { 
var heads = document.getElementsByTagName('head'); 
if (heads.length == 0) { 
alert("page must have one head element"); 
} 
var head = heads[0]; 
var script = document.createElement('script'); 
script.type = 'text/javascript'; 
script.src = url; 
// most browsers 
script.onload = callback; 
// IE 6 & 7 
script.onreadystatechange = function () { 
if (this.readyState == 'complete') { 
callback(); 
} 
} 
head.appendChild(script); 
} })(window.clover = window.clover || {}); 
// sample 
// clover.loadScript("http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js");