function* evenNumberGenerator() {
  let num = 0;
  while (true) {
    yield num;
    num += 2;
  }
}

const evenGen = evenNumberGenerator();

console.log(evenGen.next().value);
console.log(evenGen.next().value);
console.log(evenGen.next().value);
console.log(evenGen.next().value);
console.log(evenGen.next().value);