标签：loading src color func point call extends fun show
ES6之前,定义一个函数(构造器)对象,使用this定义属性
使用new & 构造器创建一个新对象
function B(x){
console.log(‘B class‘)
console.log(this);
this.x=x;
this.show=function(){console.log(3333333)}
}
console.log(typeof B)
b=new B(22)
b.show()
console.log(typeof b,b)
function Point(x,y){
this.x=x;
this.y=y;
this.show=()=>console.log(this,this.x,this.y)
console.log(‘Point ~~~~~~~~~~~~‘)
}
p=new Point(4,8)
p.show()
function Point(x,y){
console.log(this)
this.x=x;
this.y=y;
console.log(this)
this.show=()=>console.log(this,this.x,this.y)
}
p1=new Point(4,9)
console.log(p1)
function Point(x,y){
this.x=x;
this.y=y;
this.show=()=>console.log(this,this.x,this.y)
console.log(this)
console.log(‘Point ~~~~~~~~~~~~~~‘)
}
// p1=new Point(4,9)
// console.log(Point)
// console.log(p1)
// p1.show()
// inherit
function Point3D(x,y,z){
Point.call(this,x,y)
this.z=z;
console.log(‘Point3d !!!!!!!!!!!!!!!!!!!!‘)
}
console.log(Point3D)
p2=new Point3D(8,4,3)
console.log(p2)
p2.show()
console.log(Point.call)
console.log(p2.call)
new 构建一个新的通用对象,new操作符会将新对象的this值传递给Point3D构造器函数,函数为这个对象创建z属性
new后得到一个对象,使用这个对象的this来调用构造器,使用Point3D对象的this来执行Point的构造器,所以使用call方法,传入子类this
class Point{
constructor(x,y){
this.x=x;
this.y=y;
this.bb=function(){console.log(‘Point ‘,this.x,this.y,this.z)}
// this.show=()=>console.log(‘Point vv‘)
console.log(‘Point ~~~~~~~~‘)
}
show(){
console.log(this,this.x,this.y)
}
}
// console.log(Point)
// p1=new Point(5,9)
// console.log(p1)
// p1.show()
class Point3D extends Point{
constructor(x,y,z){
super(x,y)
this.z=z;
this.bb=function(){console.log(‘Point3D ‘,this)}
this.vv=()=>console.log(‘Point3D vv‘)
}
show(){
// console.log(this,this.x,this.y,this.z)
super.show()
console.log(this.z)
}
static print(){
return ‘static print‘
}
}
console.log(Point3D)
p2=new Point3D(2,44,88)
console.log(p2)
p2.show()
console.log(Point3D.print())
// Point3D.show()
p2.constructor.print()
// p2.bb()
// p2.vv()
标签：loading src color func point call extends fun show
原文地址：https://www.cnblogs.com/dissipate/p/14165844.html
