关于继承

class A{
  x=7;
  constructor() {
    this.y=10; 
  }
  a(){console.log('A')}
}
class B extends A{
  z=5;
constructor() {
    super(); 
  }
b(){
  this.a()
}
c(){
  this.b()
}
d=function(){
    console.log("D");
  }
e(){
    
 console.log(super.y);
}
}
let C=new B();
console.log(C.z)
console.log(C.x)
console.log(C.y)
C.e()