function sleepAsync (milliseconds) {
  return new Promise(resolve => setTimeout(() => resolve(`Elapsed ${milliseconds} ms`), milliseconds))
}
function sleepCallback (milliseconds, callback) {
  new Promise(resolve => setTimeout(() => resolve(`Elapsed ${milliseconds} ms`), milliseconds)).then(callback)
}

function withCallback (data, callback) {
  console.log("Start")
  sleepCallback(5000, (data) => {
    console.log("Data:", data)
  })
  console.log("End")
}

async function withoutCallback () {
  console.log("Start")
  const data = await sleepAsync(5000)
  console.log("Data:", data)
  console.log("End")
}