An illustration of how ES6 promises work

promises.ts

async function zero(): Promise<number> {
  console.log('zero');

  return 0;
}

async function add(origP: Promise<number>, inc: number): Promise<number> {
  return inc + await origP;
}

(async () => {
  const zP = zero();

  const one = await add(zP, 1);
  const two = await add(zP, 2);

  console.log(await zP, one, two);
})();