Promise.allSettled: polyfill

promise.allSettled.js

/**
 * The Promise.allSettled() method returns a promise that resolves
 * after all of the given promises have either resolved or rejected,
 * with an array of objects that each describe the outcome of each promise.
 *
 * For each outcome object, a `status` string is present.
 * If the status is "fulfilled", then a `value` is present.
 * If the status is "rejected", then a `reason` is present.
 * The value (or reason) reflects what value each promise
 * was fulfilled (or rejected) with.
 */
if (!Promise.allSettled) {
  Promise.allSettled = (promises) =>
    Promise.all(
      promises.map((promise, i) =>
        promise
          .then(value => ({
            status: "fulfilled",
            value,
          }))
          .catch(reason => ({
            status: "rejected",
            reason,
          }))
      )
    );
}

// Usage
Promise.allSettled(promises).then(console.log);