Promises Queue

promisedQueue.js

function queue (operations, finished = []) {
  let [curr, ...rest] = operations;

  return !curr ? Promise.resolve(finished) : new Promise(resolve => {
    curr()
      .then(result => {
        resolve(queue(rest, finished.concat(result)));
      })
      .catch(() => {
        resolve(queue(rest, finished));
      });
  });
}

// sample

function f (expr) {
  return () => new Promise((resolve, reject) => {
      let rand = Math.random();
      setTimeout(() => {
        // ololo
        (rand > 0.5) ? resolve(expr()) : reject();
      }, rand);
    });
}

let list = [1, 2, 3, 4, 5, 6, 7, 8, 9].map(x => f(() => x * x));
queue(list).then(data => {
  console.log(data);
});