Iterators

Description

Iterator objects enable custom iteration like CLR IEnumerable or Java Iterable. Generalize for..in to custom iterator-based iteration with for..of. Don’t require realizing an array, enabling lazy design patterns like LINQ.

Task

Your task is simple, create a counter that increments by 1 each time. You must use the iterator described below. Good luck!

Example

let fibonacci = {
  [Symbol.iterator]() {
    let pre = 0, cur = 1;
    return {
      next() {
        [pre, cur] = [cur, pre + cur];
        return { done: false, value: cur }
      }
    }
  }
}

for (let n of fibonacci) {
  // truncate the sequence at 1000
  if (n > 1000)
    break;
  console.log(n);
}

Reading: Iterators and Generators