JS语法---对象模型

Posted 2022-06-28 xiaoshayu520ly

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。。