tiny-limit

Run async functions with limited concurrency. Same API as p-limit, but ships both ESM and CJS with zero dependencies.

import { pLimit } from "tiny-limit";

const limit = pLimit(5);
const results = await Promise.all(urls.map((url) => limit(() => fetch(url))));

496 bytes gzipped. Zero dependencies.

Install

npm install tiny-limit

Usage

import { pLimit } from "tiny-limit";

const limit = pLimit(3);

const input = [
  limit(() => fetchUser(1)),
  limit(() => fetchUser(2)),
  limit(() => fetchUser(3)),
  limit(() => fetchUser(4)),
  limit(() => fetchUser(5)),
];

const users = await Promise.all(input);

Pass arguments

const limit = pLimit(2);
const result = await limit(fetch, "https://example.com");

Inspect the queue

limit.activeCount; // currently running
limit.pendingCount; // waiting in queue
limit.concurrency; // get or set the limit
limit.clearQueue(); // discard pending tasks

Differences from p-limit

p-limit v4+ is ESM-only. If you require("p-limit") in a CommonJS project, you get ERR_REQUIRE_ESM. tiny-limit works with both import and require().

| | p-limit | tiny-limit | | ------------ | ---------------------- | ------------ | | CJS support | v3 only (v4+ ESM-only) | ESM + CJS | | Dependencies | yocto-queue | 0 | | TypeScript | native (v6+) | native | | Export | default | named |

Migrating from p-limit

- import pLimit from "p-limit";
+ import { pLimit } from "tiny-limit";

One line. The rest of your code stays the same.

API

pLimit(concurrency: number): LimitFunction

Returns a limit function that queues async work up to the given concurrency. Throws if concurrency is not a positive integer (or Infinity).

limit(fn, ...args): Promise

Queues fn(...args) and returns a promise.

limit.activeCount

Number of promises currently running.

limit.pendingCount

Number of promises waiting in the queue.

limit.concurrency

Get or set the concurrency limit at runtime.

limit.clearQueue()

Discards all pending tasks.

Author

License

MIT © Ofer Shapira