class继承你一看就懂的知识点

class Parent{
    constructor(){
        this.name = 'parent';
        this.age = 88;
    }
    say(){
        console.log('hello parent');
    }
    static qqq = 666;//想给Parent设置一个私有属性，用static,这样child.qqq 也是可以调用到的
}
class Child extends Parent{
    constructor(){
        super();//写了extends 和constructor；则必须写super()
        //super其实就是Parent的constructor
        this.money = 100;
    }
    play(){
        console.log('child play')
    }
}
var xm = new Child();
console.log(xm);