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@reda/parallelize-generator-promises@1.1.2

Runs promises yielded by generators in parallel

Works with
This package works with Bun
This package works with Cloudflare Workers
This package works with Node.js
This package works with Deno
This package works with Browsers
JSR Score
100%
Published
3 weeks ago
deno add @reda/parallelize-generator-promises
import * as mod from "@reda/parallelize-generator-promises";
npx jsr add @reda/parallelize-generator-promises
import * as mod from "@reda/parallelize-generator-promises";
yarn dlx jsr add @reda/parallelize-generator-promises
import * as mod from "@reda/parallelize-generator-promises";
pnpm dlx jsr add @reda/parallelize-generator-promises
import * as mod from "@reda/parallelize-generator-promises";
bunx jsr add @reda/parallelize-generator-promises
import * as mod from "@reda/parallelize-generator-promises";

parallelize-generator-promises

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A simple utility to run promises yielded by a generator in parallel. This is incredibly useful when you need to run a bunch of tasks as fast as possible without waiting for one another.

Installation

parallelize-generator-promises is available on both npm and JSR.

To use from npm, install the parallelize-generator-promises package and then import into a module:

import { parallelizeGeneratorPromises } from "parallelize-generator-promises";

To use from JSR, install the @reda/parallelize-generator-promises package and then import into a module:

import { parallelizeGeneratorPromises } from "@reda/parallelize-generator-promises";

Polyfilling Promise.withResolvers

If you are using Node.js v20 or below, you will require a polyfill for Promise.withResolvers.

A polyfill for this is available in a separate export as part of this package. To use the provided polyfill, import it at the entrypoint of your application.

npm:

import "parallelize-generator-promises/promise-with-resolvers-polyfill";

jsr:

import "@reda/parallelize-generator-promises/promise-with-resolvers-polyfill";

Usage

import { parallelizeGeneratorPromises } from "parallelize-generator-promises";

async function* getAllProductDetails() {
  for (let page = 1; page <= 100; page++) {
    const products = await fetch(`/products?page=${page}`).then((res) =>
      res.json()
    );
    yield products.map((product) =>
      fetch(`/product/${product.id}/details`).then((res) => res.json())
    );
  }
}

for await (
  const productDetails of parallelizeGeneratorPromises(
    getAllProductDetails(),
  )
) {
  console.log(productDetails);
}

The above example will fetch all product details for one page of products at a time as fast as possible, yielding the product details in the fastest order possible to keep the iterator fed.

If a concurrency limit is required, this utility pairs very well with a semaphore library such as async-sema.

Options

Name Description
maxBufferedPromises Limits the maximum number of promises that can be buffered at any given time. Useful to manage memory usage in the case where you are generating a lot of promises that aren't being consumed at a fast enough rate. NOTE: this value must be greater than or equal to 1. By default this is undefined which means there is no limit set.
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