JS语法---对象模型

JS对象模型

定义类

字面式声明方式

ES6之前---构造器

//定义类
function Point(x,y){
    this.x = x;
    this.y = y;
    this.show = () => console.log(this,this.x,this.y);
    console.log('Point~~~~~~');
}
// console.log(Point)　　//[Function: Point]
// p1 = Point(4,5)
// console.log(p1)　　　　//undefined
p1 =new Point(4,5)              //Point~~~~~~
console.log(111,p1)             //Point { x: 4, y: 5, show: [Function] }
//继承
function Point3D(x,y,z){
    Point.call(this,x,y);
    this.z = z;
    console.log('Point3D~~');
}   
console.log(222,Point3D);       //[Function: Point3D]
p2 = new Point3D(14,15,16);     //Point~~~~~~   Point3D~~
console.log(333,p2);            //Point3D { x: 14, y: 15, show: [Function], z: 16 }
p2.show();                      //Point3D { x: 14, y: 15, show: [Function], z: 16 } 14 15

ES6中的class

//基类定义
class Point{
    constructor(x,y){/*构造器*/
        this.x = x;
        this.y = y;
    }
    show(){/*方法 */
        console.log(this,this.x,this.y);
    }
}

let p1 = new Point(10,11)
p1.show()   //Point { x: 10, y: 11 } 10 11

//继承
class Point3D extends Point{
    constructor(x,y,z){
        super(x,y)
        this.z = z
    }
}
let p2 = new Point3D(20,21,22) 
p2.show()   //Point3D { x: 20, y: 21, z: 22 } 20 21

重写方法

//基类定义
class Point{
    constructor(x,y){/*构造器*/
        this.x = x;
        this.y = y;
    }
    show(){/*方法 */
        console.log(this,this.x,this.y);
    }
}

let p1 = new Point(10,11)
p1.show()   //Point { x: 10, y: 11 } 10 11

//继承
class Point3D extends Point{
    constructor(x,y,z){
        super(x,y)
        this.z = z
    }
    show(){/*方法 */
        console.log(this,this.x,this.y,this.z);
    }
}
let p2 = new Point3D(20,21,22)  
p2.show()   //Point3D { x: 20, y: 21, z: 22 } 20 21 22

//基类定义
class Point{
    constructor(x,y){/*构造器*/
        this.x = x;
        this.y = y;
        this.show = () => console.log('Point');
        // this.show = function (){console.log(this,this.x,this.y)};
    }
}

//继承
class Point3D extends Point{
    constructor(x,y,z){
        super(x,y)
        this.z = z
        this.show = () => {console.log('Point3D')}
    }
}
let p2 = new Point3D(20,21,22)  
p2.show() //Point3D

待续。。