Object iterator with a generator

index.js

const obj = {
  sub: {
    array: [1,2,3,4,5,6,7,8,9]
  },
  *[Symbol.iterator]() {
    for (let i = 0; i < this.sub.length; i++) {
      yield this.sub[i];
    }
  }
}

This is a more concise way of creating iterators than manually returning an object with a next() function embedded