原生js实现的ul li二级联动

使用方法

        <script>
            var city={
                "name":"网站",
                "num":['niace','aaaa'],
                "sites":[ "Google", "Runoob", "Taobao" ]     //设置数据
                    }
            window.onload=function(){
                    var l=new liandong(city);   //实例化联动
            }
        </script>
        <ul id="ld">
        <ul id="ld-left">
        </ul>
        <ul id="ld-right">
        </ul>
        </ul>