var tabs=function(){
    function tag(name,elem){
        return (elem||document).getElementsByTagName(name);
    }
    //获得相应ID的元素
    function id(name){
        return document.getElementById(name);
    }
    function first(elem){
        elem=elem.firstChild;
        return elem&&elem.nodeType==1? elem:next(elem);
    }
    function next(elem){
        do{
            elem=elem.nextSibling;  
        }while(
            elem&&elem.nodeType!=1  
        )
        return elem;
    }
    return {
        set:function(elemId,tabId){
            var elem=tag("li",id(elemId));
            var tabs=tag("ul",id(tabId));
            var listNum=elem.length;
            var tabNum=tabs.length;
            for(var i=0;i<listNum;i++){
                    elem[i].onclick=(function(i){
                        return function(){
                            for(var j=0;j<tabNum;j++){
                                if(i==j){
                                    tabs[j].style.display="block";
                                    //alert(elem[j].firstChild);
                                    elem[j].firstChild.className="selected";
                                }
                                else{
                                    tabs[j].style.display="none";
                                    elem[j].firstChild.className="";
                                }
                            }
                        }
                    })(i)
            }
        }
    }
}();
tabs.set("nav","menu_con");//执行