async function* generateSequence(start, end) {
  for (let i = start; i <= end; i++) {
    await new Promise(resolve => setTimeout(resolve, 1000));
    yield i;
  }
}

(async () => {
  let generator = generateSequence(1, 5);
  for await (let value of generator) {
    console.log(value); // 1, then 2, then 3, then 4, then 5 (with delay between)
  }
})();