QuestQueue

A concurrency-limited async task queue. At most simultaneous tasks run at once; the rest wait, and a slot is refilled as each one finishes. Use it for batch uploads or batch requests — anything you cannot fire all at once.

API

new QuestQueue({ simultaneous })

Parameter	Description	Type	Default
simultaneous	Max concurrency; <= 0 means 1	number	1

Member	Description
add(task)	Enqueue a task, get its own result promise. Starts when a slot is free
allSettled(tasks)	Enqueue a batch; resolves like Promise.allSettled, in input order
onIdle()	Wait for the queue to drain
clear()	Drop everything not yet started (running tasks are untouched)
running / pending / executed / idle	Live counters

Example

import { QuestQueue } from 'ranuts';

const queue = new QuestQueue({ simultaneous: 3 });
const results = await Promise.all(urls.map((url) => queue.add(() => fetch(url))));

// Or fire and forget, then wait for everything including failures
urls.forEach((url) => queue.add(() => fetch(url)).catch(report));
await queue.onIdle();

Notes

1. FIFO — tasks run in the order they were added.
2. One failure does not stall the queue. Each task rejects its own promise; the next task starts regardless.
3. A task that throws synchronously is caught too, so it cannot leak out of add() and leave the concurrency counter stuck.
4. allSettled keeps input order and reports each outcome separately.

Rewritten in 0.3

The previous implementation was unusable: add() only enqueued (you had to call running() by hand), it popped LIFO, one promise carried the results of unrelated tasks, and allSettled wrote results starting at index 1 and resolved on the first task. The constructor's total option is gone — use onIdle() or allSettled(tasks) instead.