Promise queue with concurrency control

globalQueue.js

const queue = (id, concurrency = 1) => {
  const d = { running: 0, queue: [] };
  const c = (globalThis._RQ ?? {})[id] ?? d;
  globalThis._RQ = { ...(globalThis._RQ ?? {}), [id]: c };
  const inc = (fn) => (c.running++, fn());
  return (task) =>
    (c.running < concurrency
      ? Promise.resolve(inc(task))
      : new Promise((res) => c.queue.push(() => res(inc(task))))
    ).finally(
      () => (c.running--, c.queue.length > 0 ? c.queue.shift()() : null)
    );
};

queue.js

export const queue = (concurrency = 1) => {
  let running = 0;
  const queue = [];
  const inc = (fn) => (running++, fn());
  const run = (res) => (
    running--, queue.length > 0 ? queue.shift()() : null, res
  );

  return (task) =>
    (running < concurrency
      ? Promise.resolve(inc(task))
      : new Promise((res) => queue.push(() => res(inc(task))))
    ).then(run);
};

export const queueFn = (concurrency, fn) => {
  const addTask = queue(concurrency);
  return (...args) => addTask(() => fn(...args));
};