动态加载新的js文件

//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;
}
//加载新的js
function GetJsData(src,callback){
    var head=document.getElementsByTagName("head")[0];
    var js=document.createElement("script");
    js.setAttribute("src",src);
    js.onload=js.onreadystatechange=function(){
        if(!this.readyState||this.readyState=="loaded"||this.readyState=="complete"){
            head.removeChild(js);
            if(callback) callback();
        }
    }
    head.appendChild(js);
}

VeryCD的

if (typeof(VeryCD) != "object") {
    var VeryCD = {}
}
VeryCD.is_ie = navigator.appName == "Microsoft Internet Explorer" ? true: false;
VeryCD.$import = function(jsfile, onloadfun, defer) {
    VeryCD._IMPORT_JSFILE = VeryCD._IMPORT_JSFILE || {};
    if (!VeryCD._IMPORT_JSFILE[jsfile]) {
        var s = "script";
        VeryCD._IMPORT_JSFILE[jsfile] = 1;
        var obj = document.createElement("script");
        obj.src = jsfile;
        if (defer) {
            obj.defer = "defer";
            obj.setAttribute("defer", "defer")
        }
        if (onloadfun) {
            if (typeof onloadfun != "function") {
                var onloadfunstr = onloadfun;
                onloadfun = function() {
                    try {
                        eval(onloadfunstr)
                    } catch(e) {}
                }
            }
            if (VeryCD.is_ie) {
                obj.onreadystatechange = function() {
                    if (this.readyState == "complete" || this.readyState == "loaded") {
                        onloadfun()
                    }
                }
            } else {
                obj.onload = onloadfun
            }
        }
        var s = document.getElementsByTagName("script")[0];
        s.parentNode.insertBefore(obj, s)
    }
};
VeryCD.$import('http://j.ssajax.cn/js/quote/jquery/jquery-1.5.1.min.js',ok,false);
function ok(){$('#test').html('is ok');alert('is ok');};

百度tangram的

baidu.script = baidu.script || {};
baidu.script._createScriptTag = function(scr, url, charset){
    scr.setAttribute('type', 'text/javascript');
    charset && scr.setAttribute('charset', charset);
    scr.setAttribute('src', url);
    document.getElementsByTagName('head')[0].appendChild(scr);
};
baidu.script._removeScriptTag = function(scr){
    if (scr.clearAttributes) {
        scr.clearAttributes();
    } else {
        for (var attr in scr) {
            if (scr.hasOwnProperty(attr)) {
                delete scr[attr];
            }
        }
    }
    if(scr && scr.parentNode){
        scr.parentNode.removeChild(scr);
    }
    scr = null;
};
baidu.script.getscript = function (url, opt_callback, opt_options) {
    var scr = document.createElement("SCRIPT"),
        scriptLoaded = 0,
        options = opt_options || {},
        charset = options['charset'],
        callback = opt_callback || function(){},
        timeOut = options['timeOut'] || 0,
        timer;
    
    // IE和opera支持onreadystatechange
    // safari、chrome、opera支持onload
    scr.onload = scr.onreadystatechange = function () {
        // 避免opera下的多次调用
        if (scriptLoaded) {
            return;
        }
        
        var readyState = scr.readyState;
        if ('undefined' == typeof readyState
            || readyState == "loaded"
            || readyState == "complete") {
            scriptLoaded = 1;
            try {
                callback();
                clearTimeout(timer);
            } finally {
                scr.onload = scr.onreadystatechange = null;
                baidu.script._removeScriptTag(scr);
            }
        }
    };

    if( timeOut ){
        timer = setTimeout(function(){
            scr.onload = scr.onreadystatechange = null;
            baidu.script._removeScriptTag(scr);
            options.onfailure && options.onfailure();
        }, timeOut);
    }
    
    baidu.script._createScriptTag(scr, url, charset);
};