能动态加载js的方法

//加载新的js
function _GetJsData(url, callback) {
    var scripts = document.createElement("script");
    document.body.appendChild(scripts);

    scripts.onload = function() {
        callback();
        document.body.removeChild(this);
    };
    scripts.onreadystatechange = function() {
        if (this.readyState == "loaded") {
            callback();
            document.body.removeChild(this);
        }
    };
    scripts.charset = "GBK";
    scripts.src = url;
}
_GetJsData('http://www.uefirst.com/index.js',isok);
var isok=function(){alert('isok')};