qualaio / one-way

Async Utils for Humans

One-Way ➡️

Super small library to add some syntax sugar for looping over arrays asynchronously

feel free to just copy the 5 lines of code in your own util library

or

Install

npm install one-way

Usage

import { asyncForEach } from 'one-way';

const orderedList = [1, 2, 3, 4, 5];
let outputList: number[] = [];

async function sleep(ms = 15_000) {
  return new Promise(resolve => {
    setTimeout(resolve, ms);
  });
}

await asyncForEach(orderedList, async num => {
  await sleep(100); // do something asyncronous
  // note this will have typescript goodness
  outputList.push(num);
});

Why this library

1. For a long time I thought this was an anti-pattern. That one should leverage the Promise.all and map or forEach primitives. But after a few years and using this on multiple teams this has become a valuable tool in code reability.
2. How many time have I google, how does one loop through a loop in serial with asynchronous code

Our team using these methods have reduced tricky errors -- hopefull it can help you and your team as well.

Under the covers

... there is soooo little code in this library we can list it here, if you do not want to add a dependency feel free just to copy the code:

this is the main function

export async function asyncForEach<I>(array: I[], callback: (item: I, idx: number) => Promise<void>): Promise<void> {
  for (const item of array.keys()) {
    await callback(array[item], item);
  }
}

or just look at the other helper functions here: link