next-resolver

^{Social Media Photo by Jan Genge on Unsplash}

A utility to simpify the repeated unique ID + promise dance.

import nextResolver from 'next-resolver';

const [next, resolve] = nextResolver();

// next unique identifier and its promise
const [id, promise] = next();

// pass the promise around, hold the id ...
// ... so that whenever it's done:
if (condition) {
  resolve(id, value);

  // or reject via
  resolve(id, null, new Error('reason'));
}

The default nextResolver() accepts an optional callback that will receive a unique identifier that can be used to return something else:

// use strings instead of numbers as IDs
const [next, resolve] = nextResolver(String);

const [id, promise] = next();
typeof id; // string

// use any Map key variant
const [next, resolve] = nextResolver(id => {
  // make it stronger (not really useful)
  return `${id}-${crypto.randomUUID()}`;
  // make it a unique ref
  return { id };
});

Please note that if the returned value is still awaited, the next id will be passed to create a new identifier (so don't put too much logic within the id creation, it's already granted to be unique per that logic/session).

This is mostly needed in case you want to brand your async operations, so that something like a prefix would be enough:

const [next, resolve] = nextResolver(id => `my-logic-${id}`);

And that's all folks 🥕