1.原型继承

原型继承

当原型中存在引用类型，存在数据被修改的问题

    <script>
        function Box() {
            this.name="lee";
        }
        function Desk() {
            this.age="22";
        }
        Desk.prototype=new Box();//Desk继承了Box形参了原型链
        var desk=new Desk();
        //    console.log(desk.name+desk.age)
        function Table() {
            this.level="AAAAA";
        }
        Table.prototype=desk;
        var tab=new Table();
        console.log(desk instanceof Table)
    </script>