promise-serial-example.js

const delayedReturn = (i) => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log(i);
      resolve(i);
    }, 1000);
  });
};

async function* stepSerial(count) {
  for (var i = 0; i < count; i++) {
    yield await delayedReturn(i);
  }
}

async function accumulateSerial(count) {
  const acc = []; 
  for await (const step of stepSerial(count)) {
    acc.push(step);
  }
  return acc;
}

async function init() { 
  const foobar = await accumulateSerial(5);
  console.log('foobar', foobar);
}

init();