JavaScript 面向对象（封装、继承、多态）多种方式实现完全总结

function Person(name, agei){ 
    // public
    this.name = name;// 可直接通过对象点语法调用
    // private
    var age = agei;// 不可通过对象点语法调用
    this.getAge = function(){//getter
        return age;
    }
    this.setAge = function(a){//setter
        age = a;
    }
}
Person.prototype.show = function(){
    var str = this.name + " "+ this.getAge();
    //报错分析： 1.不加this表示访问原型属性 2.原型不能访问所在类的私有属性和方法
    // var str = name + " "+ age;
    return str;
}
//必须使用new关键字创建对象，否则this指向window
var p1 = new Person('csxiaoyao', 25);
//调用对象公开属性和私有属性(undefined)
console.log(p1.name + " " + p1.age);//csxiaoyao undefined
//调用对象方法
p1.setAge(20);
console.log(p1.getAge());//20
//调用原型方法
console.log(p1.show());//csxiaoyao 20
var p2 = new Person();
//利用对象动态性添加属性
p1.n = "sunshine";
console.log(p1.n);//sunshine

function Person(name, age){
    this.name = name;
    this.age = age;
}
//1.给原型对象中添加成员（通过对象的动态特性）不是严格意义上的继承
Person.prototype.sayHello = function () {
    console.log("sayHello1");
}
// p1对象继承原型
var p1 = new Person("csxiaoyao",25);
p1.sayHello();//sayHello1
//2.直接替换原型对象
var parent = {
    sayHello : function () {
        console.log("sayHello2");
    }
}
Person.prototype = parent;
var p2 = new Person("csxiaoyao",25);
p2.sayHello();//sayHello2

function Stu(name, age){
    this.name = name;
    this.age = age;
    this.show = function(){
        console.log(this.name + " " + this.age);
    }
}
function MidStu(name, age, money) {
    this.stu = Stu;//为当前对象创建Stu构造方法，赋值给stu属性
    this.stu(name, age);//调用构造方法，为当前构造函数添加name、age、show
    this.payFee = function(){//添加子类方法
        console.log("缴费" + money * 0.8);
    }
}
function Pupil(name, age, money) {
    this.stu = Stu;
    this.stu(name, age);
    this.payFee = function(){
        console.log("缴费" + money * 0.5);
    }
}
var midStu = new MidStu("csxiaoyao", 13, 10000);
var pupil = new Pupil("sunshine", 10, 10000);
midStu.show();//csxiaoyao 13
midStu.payFee();//缴费8000
pupil.show();//sunshine 10
pupil.payFee();//缴费5000

function Stu(name,age){
    this.name=name;
    this.age=age;
    this.show=function(){
        console.log(this.name+" "+this.age);
    }
}
function MidStu(name,age){
    Stu.call(this,name,age);//调用父类构造函数
    //Stu.apply(this,[name,age]); 
    this.pay=function(fee){
        console.log("学费:"+fee*0.8);
    }
} 
function Pupil(name,age){ 
    Stu.call(this,name,age);
    this.pay=function(fee){
        console.log("学费:"+fee*0.5);
    }
}
var midstu = new MidStu("csxiaoyao",15); 
var pupil = new Pupil("sunshine",12); 
midstu.show();// csxiaoyao 15
midstu.pay(100);// 学费:80
pupil.show();// sunshine 12
pupil.pay(100);// 学费:50

//js通过判断参数个数、类型来实现重载
function Person(){
    this.test = function (){
        if(arguments.length==1 && (typeof arguments[0])==="string"){
            this.show1(arguments[0]);
        }else if(arguments.length==1 && (typeof arguments[0])==="number"){
            this.show2(arguments[0]);
        }else if(arguments.length==2){
            this.show3(arguments[0],arguments[1]);
        }else if(arguments.length==3){
            this.show4(arguments[0],arguments[1],arguments[2]);
        }
    }
    this.show1=function(a){
        console.log("function(string):"+a);
    }
    this.show2=function(a){
        console.log("function(number):"+a);
    }
    this.show3=function(a,b){ 
        console.log("function(a,b):"+a+","+b); 
    }
    function show4(a,b,c){ 
        console.log("function(a,b,c):"+a+","+b+","+c); 
    }
} 
var p1=new Person();
p1.test("a");//function(string):a
p1.test(1);//function(number):1
p1.test("sun","shine");//function(a,b):sun,shine
// p1.test("sun","shine","studio");//报错 is not a function

// Master类
function Master(name){
    this.nam=name;
}
//原型法添加成员函数
Master.prototype.feed=function (animal,food){
    console.log("给 "+animal.name+" 喂 "+ food.name);
}
// 食物
function Food(name){
    this.name=name;
}
function Fish(name){
    this.food=Food;
    this.food(name);
}
function Bone(name){
    this.food=Food;
    this.food(name);
}
// 动物
function Animal(name){
    this.name=name;
}
function Cat(name){
    this.animal=Animal;
    this.animal(name);
}
function Dog(name){
    this.animal=Animal;
    this.animal(name);
}
var cat=new Cat("猫");
var fish=new Fish("鱼");
var dog=new Dog("狗");
var bone=new Bone("骨头");
//创建一个主人
var master=new Master("csxiaoyao"); 
master.feed(dog,bone);//给 狗 喂 骨头
master.feed(cat,fish);//给 猫 喂 鱼