Promise Sequence Example

promise-sequence.js

function transaction(delay) {
  return new Promise((resolve, reject) => {
    console.log(delay, "seconds");
    setTimeout(() => resolve(delay), delay * 1000);
  });
}

function main() {
  return [5, 4, 3, 2, 1].reduce((prev, next) => prev.then(() => transaction(next)), Promise.resolve());
}

if (require.main === module) {
  main().then(() => console.log("Finished"));
  console.log("Promise Sequence Example");
}