根据不同状态动态加载js。很像原生的AJAX
function loadJs(loadUrl,callback){
var script = doucument.creteElement('script');
var head = document.getElementsByTagName('head')[0];
script.src = loadUrl;
script.type = "text/javascript";
//判断服务器
if(navigator.userAgent.indexOf('IE') != -1){//IE
script.onreadystatechange = function(){
//判断资源绑定成功
if(/^(loaded|complete)$/.test(readystate)){
script.onreadystatechange = null;
callback();
}
}
script.onerror = function(){
....
}
}else{
script.onload = function(){
script.onload = null;
callback();
}
}
}
function callback(){
alert("回调函数");
}
