promiseAll

// const [user, posts, tags] = await Promise.all([
//   fetch('/api/user').then((r) => r.json()),
//   fetch('/api/posts').then((r) => r.json()),
//   fetch('/api/tags').then((r) => r.json()),
// ]);

/**
 * @param {Array} iterable
 * @return {Promise<Array>}
 */
export default function promiseAll(iterable) {
  return new Promise((resolve, reject) => {
    const results = [];
    let complete = 0;
    if (iterable.length === 0) {
      resolve([]);
      return;
    }

    iterable.forEach((promise, idx) => {
      Promise.resolve(promise)
        .then((value) => {
          results[idx] = value;
          complete++;
          if (complete === iterable.length) {
            resolve(results);
          }
        })
        .catch((err) => {
          reject(err);
        })
    });
  });
}