类的封装和继承最佳方法和解析

27 May 2015

1.最佳的封装方式--组合模式，构造函数模式和原型模式混合

                    function Person(name, age, job){
                        this.name = name;
                        this.age = age;
                        this.job = job;
                        this.friends = ["aaa","bbb","ccc"];
                    }

                    Person.prototype = {
                        constructor: Person,
                        sayName: function(){
                            return this.name;
                        }
                    }

                    var person1 = new Person("sunny","11","nnn");
                    var person2 = new Person("stella","12","ppp");
                    person1.friends.push("ddd");
                    console.log(person1.friends);
                    //["aaa", "bbb", "ccc", "ddd"]
                    console.log(person2.friends);   
                    //["aaa", "bbb", "ccc"]
                    console.log(person1.sayName());
                    console.log(person2.sayName());
                    console.log(person1.sayName == person2.sayName);
                    //true
                

这种方式中，将构造函数模式用于对象属性，使得每个实例的属性都私有化。将原型模式用于对象方法，使得实例的对象可以共享。

2.最佳的继承方式--组合模式

                    //继承Person
                    function Sub(name, age, job, id){
                        //调用Person函数
                        Person.call(this,name,age,job);
                        this.id = id;
                    }
                    //子类的原型去继承父类的实例
                    Sub.prototype = new Person();

                    //如果用字面量的方式定义的话，会导致上一行代码无效，所以要用下面的方式添加方法
                    Sub.prototype.sayAge = function(){
                        return this.age;
                    }

                    var sub1 = new Sub("first","33","sss",9);
                    var sub2 = new Sub("second","77","sss",7);
                    console.log(sub1.name);
                    console.log(sub2.name);
                    console.log(sub2.id);
                    console.log(sub1.sayName());
                    console.log(sub1.sayAge());