example.js

function foo()
{
  const {promise, resolve, reject} = Promise.withResolvers()

  setTimeout(() => {
    resolve('DONE')
  }, 2000)
  
  
  return promise
}


function foo2()
{
  const {promise, resolve, reject} = withResolvers()

  setTimeout(() => {
    resolve('DONE 2')
  }, 2500)
  
  
  return promise
}

// polyfill
function withResolvers() {
  let resolve, reject;
  const promise = new Promise((res, rej) => {
    resolve = res;
    reject = rej;
  });
  return { promise, resolve, reject };
}

// Použití:
const { promise: aliasOnlyForTesting, resolve } = withResolvers();



(async() => {
  const data = await foo()
  console.log(data)
  
  const data2 = await foo2()
  console.log(data2)
})()