Can I drain the pending queue without running them?

Yes, you can drain the pending queue without running the tasks using the clearQueue() method.

According to the API documentation in [index.d.ts:L16-L24], clearQueue() will "Discard pending promises that are waiting to run." This means any tasks in the queue that haven't started executing yet will be removed without being executed.

Here's what happens:

• Pending tasks are discarded — their internal fn is never called
• Already running tasks continue — clearQueue() does not cancel promises that are already executing
• Optional rejection — if you initialize the limiter with rejectOnClear: true, pending promises will be rejected with an AbortError instead of just being silently discarded

Example from the test suite [test.js:L183-L191]:

const limit = pLimit(1);
Array.from({length: 1}, () => limit(() => delay(1000)));
Array.from({length: 3}, () => limit(() => delay(1000)));

await Promise.resolve();
t.is(limit.pendingCount, 3);  // 3 tasks waiting
limit.clearQueue();
t.is(limit.pendingCount, 0);  // All pending tasks removed

If you need pending promises to be properly rejected (recommended when using Promise.all), use the rejectOnClear option as shown in [test.js:L197-L211].

FOLLOW_UPS:

• How do I enable rejection when clearing the queue?
• What's the difference between activeCount and pendingCount?
• Can I adjust concurrency while tasks are running?