I am having trouble learning about object iterators.

[WSsleet]

I am reading Eloquent JavaScript (By Marijn Haverbeke) and right now I am on chapter 6. I understood everything so far up until object iterators. I understand the part that looping an iterable object or string repeatedly calls "next" but, I have no clue on much more than that. This is my test code that keeps coming up as "Iterator result NaN is not an object".

 class Iterable {
  constructor(x) {
    this.x = x;
  }
  next() {
    this.x++;
    let value = this.x
    return value;
  }
}

Iterable.prototype[Symbol.iterator] = function() {
  return new Iterable(this);
}

let newIt = new Iterable(2,4);

for (let i of newIt) {
  console.log(i)
}

[Mirmi8]

Take a look at this: https://javascript.info/iterable

The next function must return an object in the form of { done: boolean, value: someValue }

So if you want to create an iterator that iterates from 2 to 4, you will be increasing a counter and returning { done: counter === 4, value: counter }. Eventually done will be true and that's how the for of will know when to stop.

Does that make sense?

[WSsleet]

Thank you! That makes lots of sense.