Concurrent processing

Runs up to concurrency calls at the same time. Results are emitted in the order the calls complete, not in the order of the input.

import { setTimeout as sleep } from "node:timers/promises";

const delays = [60, 10, 30];
const work = async (ms: number) => {
    await sleep(ms);
    return ms;
};

await chain(delays).concurrentMap({ concurrency: 3 }, work).toArray();
// => [10, 30, 60]
await chain(delays).concurrentMap({ concurrency: 1 }, work).toArray();
// => [60, 10, 30]

As in map, an optional third argument turns an error thrown by the mapper into a value.

See concurrentMap and ConcurrentMapOptions.