1:  class Range {

   2:      constructor(start, end, step = 1) {

   3:          this.start = start;

   4:          this.end = end;

   5:          this.step = step;

   6:      }

   7:  

   8:      *[Symbol.iterator]() {

   9:          let current = this.start;

  10:          while (current <= this.end) {

  11:              yield current;

  12:              current += this.step;

  13:          }

  14:      }

  15:  }

  16:  

  17:  const range = new Range(1, 5);

  18:  for (const num of range) {

  19:      console.log(num); // 1, 2, 3, 4, 5

  20:  }

  21:  

  22:  console.log([...new Range(10, 15, 2)]); // [10, 12, 14]