1.自己写着玩的代码，一个返回一个JSON对象的函数：

var somebody = function(arg1, arg2){
    var name = arg1;
    var age = arg2;
    var setName = function(arg3){
        name = arg3;
    }
    var getName = function(){
        return name;
    }
    var setAge = function(arg4){
        age = arg4;
    }
    var getAge = function(){
        return age;
    };
    return {setName:setName,getName:getName,setAge:setAge,getAge:getAge};
}

rose = somebody("rose",15);
jack = somebody("jack",21);
rose.setAge(17);
console.log(jack.getAge(),rose.getAge());

结果是21 17

请问为什么JSON中只存储了函数引用，rose和jack却可以拥有各自的值？Javascript的原型链在这里怎么理解？