[Async] Async await over promises

async.ts

const random = () => { return Promise.resolve(Math.random()); }

// Callback hell
const sum randomAsyncAwait = () => {
  let first;
  let second;
  let third;
  
  return random.then(val => {
    first = val;
    return random();
  }).then(val => {
    second = val;
    return random();
  }).then(val => {
    third = val;
    return first + second + third;
  });
}

// Beytter 
const randomAsyncAwait = async () => {
  const first = await random();
  const second = await random();
  const third = await random();
}