concurrent.mjs

export const parallel = (tasks, fn) => Promise.all(tasks.map(task => fn(task)));

export const serial = (tasks, fn) => tasks.reduce((promise, task) => promise.then(previous => fn(task, previous)), Promise.resolve(null));

export const concurrent = async (tasks, fn, limit = 8) => {
  const chunks = Array.from(Array(Math.ceil(tasks.length / limit))).map((x, i) => tasks.slice(i * limit, i * limit + limit));
  for (const chunk of chunks) {
    await Promise.all(chunk.map((task) => fn(task)));
  }
};