deferred.ts

function deferred<T>() {
  let resolve: (value: PromiseLike<T> | T) => void;
  let reject: (reason: Error) => void;
  let promise = new Promise<T>((_resolve, _reject) => {
    resolve = _resolve;
    reject = _reject;
  });

  return { promise, resolve, reject };
}
function randomIntFromInterval(min: number, max: number) {
  return Math.floor(Math.random() * (max - min + 1) + min);
}
async function myAsyncFunction(val: string) {
  const { resolve, promise } = deferred<string>();

  setTimeout(
    () => resolve(`${val} - computed`),
    randomIntFromInterval(200, 3000)
  );
  return promise;
}

async function main() {
  for (let i = 0; i < 10; i++) {
    const input = i + 1 + '';
    myAsyncFunction(input)
      .then(v => console.log(v))
      .catch(e => console.error(`${i} failed`));
  }
}

main();