JS动态加载js文件

    function loadScript(src,callback){
        //生成新script
        var newScript = document.createElement('script');
        newScript.type = 'text/javascript';
        if(window.attachEvent){
            newScript.src = src + (new Date().getTime());
        }else{
            newScript.src = src;
        }
        document.getElementsByTagName('head')[0].appendChild(newScript);

        //判断是否加载完成
        if(window.attachEvent){//ie
            newScript.onreadystatechange = function(){
                if( !this.readyState || this.readyState == "loaded" || this.readyState == "complete" ){
                    newScript.onreadystatechange = null;
                    if( callback && typeof callback === 'function' ){ callback() }
                }
            }
        }else{
            newScript.onload = function(){
                newScript.onload = null;
                if( callback && typeof callback === 'function' ){ callback() }
            }
        }
    }