RangeIterator.js

class RangeIterator {

  constructor({
    start = 0,
    end = 1000,
    step = 1
  }) {
    this.start = start;
    this.end = end;
    this.step = step;
  }

  [Symbol.iterator]() {

    let start = this.start;
    const iterable = {
		
      // Next fn complying with Iterator protocol.
      next: () => {

        if (start <= this.end) {
          const result = {
            value: start,
            done: false
          };
          start += this.step;
          return result;
        }

        return {
          done: true
        };
      }
    }
    return iterable;;
  }
}

const range = new RangeIterator({
  start: 0,
  end: 20,
  step: 5
});
console.log(...range); // 0 5 10 15 20