JS面向对象高级特性

时间 2019-11-10

原文原文链接

对象的建立能够经过两种方式，第一种经过对象初始化的方法： javascript

 var person={
                name:"xingoo",
                age:26,
                say:function(){
                    console.log("say something");
                },
                action:function(){
                    console.log("do something");
                }
            };

            console.log(person.name);
            console.log(person.age);
            person.say();
            person.action();

第二种方式经过构造函数建立：
html

 function student(name,age){                this.name = name;                this.age = age;                this.say = function(){
                    console.log("say something");
                }                this.action = function(){
                    console.log("do something");
                }
            }            var xingoo = new student("xingoo",27);
            console.log(xingoo.name);
            console.log(xingoo.age);
            xingoo.say();
            xingoo.action();

对象的属性

对象的属性分为对象属性、私有属性和类属性。java

　　对象属性须要建立对象后才能使用；闭包

　　私有属性在内部能够直接使用，在外部须要经过闭包才能使用。app

　　类属性能够经过对象名称直接使用。ide

function func(){                this.objPro1 = "对象属性";
                func.prototype.objPro2 = "对象属性";                var privatePro = "私有属性";
            }
            func.classPro = "类属性";

            console.log(func.classPro);            var f = new func();
            console.log(f.objPro1);
            console.log(f.objPro2);            <!-- 私有属性能够经过闭包获取 -->

对象的方法

　　对象方法包括：对象方法，私有方法和类方法，使用相似前面的属性。函数

 function demoFunc1(){                var privateFunc = function(){
                    console.log("this is privateFunc");
                };

                privateFunc();                this.objFunc1 = function(){
                    console.log("this is objFunc1");
                };
                demoFunc1.prototype.objFunc2 = function(){
                    console.log("this is objFunc2");
                };
            }
            demoFunc1.classFunc = function(){
                console.log("this is classFunc");
            };
            demoFunc1.classFunc();            var f = new demoFunc1();
            f.objFunc1();
            f.objFunc2();

继承、封装与多态

　　JS要想实现继承，须要经过apply方法或者prototype实现。ui

　　若是单纯的使用apply方法，子类的原型是子类；若是使用prototype，那么子类的原型也将继承父类。this

　　例以下面的代码：spa

 function Animal(name,age){                this.name = name;                this.age =age;                this.say = function(){
                    console.log("animal say something");
                }
            }            function Cat(name,age){
                Animal.apply(this,[name,age]);
            }            <!-- Cat.prototype = new Animal();-->            var cat1 = new Cat("xingoo",3);
            console.log(cat1.name);
            console.log(cat1.age);
            cat1.say();

上面代码中，cat的原型是cat；

若是开启注释的部分，能够发现，cat类的原型也变成了Animal。

子类的方法会覆盖父类的方法，即表现出多态性：

  function Pig(name,age){                this.say = function(){
                    console.log("i am pig");
                }
            }
            Pig.prototype = new Animal();            function Dog(name,age){                this.say = function(){
                    console.log("i am dog");
                }
            }
            Dog.prototype = new Animal();            function say(animal){                if(animal instanceof Animal){
                    animal.say();
                }
            }            var dog = new Dog();            var pig = new Pig();
            say(dog);
            say(pig);

使用到的所有代码：

<!doctype html>

<html>

<head>

</head>

<body>

var person={

name:"xingoo",

age:26,

say:function(){

console.log("say something");

action:function(){

console.log("do something");

}

};

console.log(person.name);

console.log(person.age);

person.say();

person.action();

function student(name,age){

this.name = name;

this.age = age;

this.say = function(){

console.log("say something");

}

this.action = function(){

console.log("do something");

}

var xingoo = new student("xingoo",27);

console.log(xingoo.name);

console.log(xingoo.age);

xingoo.say();

xingoo.action();

function func(){

this.objPro1 = "对象属性";

func.prototype.objPro2 = "对象属性";

var privatePro = "私有属性";

}

func.classPro = "类属性";

console.log(func.classPro);

var f = new func();

console.log(f.objPro1);

console.log(f.objPro2);

function demoFunc1(){

var privateFunc = function(){

console.log("this is privateFunc");

};

privateFunc();

this.objFunc1 = function(){

console.log("this is objFunc1");

};

demoFunc1.prototype.objFunc2 = function(){

console.log("this is objFunc2");

};

}

demoFunc1.classFunc = function(){

console.log("this is classFunc");

};

demoFunc1.classFunc();

var f = new demoFunc1();

f.objFunc1();

f.objFunc2();

function Animal(name,age){

this.name = name;

this.age =age;

this.say = function(){

console.log("animal say something");

}

function Cat(name,age){

Animal.apply(this,[name,age]);

}

var cat1 = new Cat("xingoo",3);

console.log(cat1.name);

console.log(cat1.age);

cat1.say();

function Pig(name,age){

this.say = function(){

console.log("i am pig");

}

Pig.prototype = new Animal();

function Dog(name,age){

this.say = function(){

console.log("i am dog");

}

Dog.prototype = new Animal();

function say(animal){

if(animal instanceof Animal){

animal.say();

}

var dog = new Dog();

var pig = new Pig();

say(dog);

say(pig);

</script>

</body>

</html>