Show some properties of javascript mixins

mixins.js

let HiMixin = Base => class extends Base {
  hi () {
    console.log('hi')
  }
}

let ByeMixin = Base => class extends Base {
  bye () {
    console.log('bye')
  }
}

class Base { }
class HiByeBase extends ByeMixin(HiMixin(Base)) {}
const b = new HiByeBase()
b.hi()
b.bye()

console.log(b instanceof HiByeBase)
console.log(b instanceof ByeMixin)
console.log(b instanceof HiMixin)
console.log(b instanceof Base)