//动态原型模式function Box(name,age){    this.name = name;    this.age = age;    this.family = [‘哥哥‘,‘姐姐‘,‘妹妹‘];    if(typeof this.run != ‘function‘){        //判断this.run是否存在        Box.prototype.run = function(){            return this.name + this.age + ‘运行中...‘;        };    }    }//原型的初始化，只要第一次初始化就可以了，没必要每次都初始化var box1 = new Box(‘Lee‘,100);alert(box1.run());var box2 = new Box(‘Jak‘,200);alert(box2.run());