many-promises

many-promises allows sequential or parallel promise evaluation, including limiting number of promises that can be in progress at the same time. Includes Typescript typings, but can be used in Javascript projects as well.

Installation

npm install many-promises

Example

import execute from 'many-promises';

const items = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const job = (item) => Promise.resolve(item * 2);

const results = await execute({ items, job });
// Will call `job` for every `item` in `items` and await until all promises are resolved.
// results - [2, 4, 6, 8, 10, 12, 14, 16, 18, 20];

// All promises in parallel:
const results = await execute({ items, job });
// All promises sequentially:
const results = await execute({ items, job, concurrentLimit: 1 });
// Maximum 3 jobs at the same time, but each job has a minimum 200ms duration:
const results = await execute({ items, job, concurrentLimit: 3, minJobTime: 200 });

Reference

execute(options: ExecuteOptions)

type ExecuteOptions<ItemType, ResultType> = {
  items: ItemType[];
  job: (item: ItemType) => Promise<ResultType> | ResultType;
  concurrentLimit?: number | undefined | null;
  minJobTime?: number | undefined | null;
};

Note: Types ItemType and ResultType are usually inferred and you don't need to specify them explicitly.

items

Array of items of any type.

job

A function with one argument - which is an item from the items array.

concurrentLimit (optional)

Maximum number of Promises that can be in progress at the same time. Default - undefined

minJobTime (optional)

Minimum time of execution for one job. If a job finishes earlier, next job will wait for this timeout to end before starting. Default - undefined