js中面向对象

        var a = {
            name: ‘小米‘
        };
        //拷贝继承
        function extend(obj1, obj2) {
            for (var attr in obj2) {
                obj1[attr] = obj2[attr];
            }
        }
        //原型继承
            var b=cloneObj(a);
            b.name=‘小乔‘;
            alert(a.name);
            alert(b.name);
            function cloneObj(obj) {
                var F=function () {};
                F.prototype=obj;
                return new F();
            }
        //类式继承
        function A() {//父类
            this.name=‘小米‘;
        }
        A.prototype.showName=function () {
            alert(this.name);
        }
        function B() {//子类
            A.call(this);//属性和方法分开继承
        }
        var F=function () {};
        F.prototype=A.prototype;
        B.prototype=new F();
        B.prototype.constructor=A;//修正指向问题
        var b1=new B();
        b1.name=‘笑笑‘;
        b1.showName();