RangeGenerator.js

class RangeGenerator {

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

  *[Symbol.iterator]() {
    let start = this.start;
    while (start <= this.end) {
      yield start;
      start += this.step;
    }
  }
}

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