gc-hook

A simplified FinalizationRegistry approach that works:

it does the right thing by never leaking the reference meant to be notified
it allows overriding the returned proxy with any other more complex wrapper or indirection
it allows references owners to drop from the registry explicitly, either via the held reference or an explicit token, if passed as extra option
it avoids understanding how the FinalizationRegistry works, helping you to focus on more complex issues instead of re-implementing the same dance over and over

Example

// available as commonjs too
import { create, drop } from 'gc-hook';

// keep a count of all passed references created here
let references = 0;

// notify how many references are still around
const onGarbageCollected = myUtility => {
  console.log(--references, 'references still used');
};

export default options => {
  const myUtility = { ...options, do: 'something' };
  console.log(++references, 'references provided');
  // return a proxy to avoid holding directly myUtility
  // while keeping the utility in memory until such proxy
  // is not needed, used, or referenced anymore
  return create(myUtility, onGarbageCollected);
};

// as module consumer
import createUtility from './module.js';

let util = createUtility({some: 'thing'});
// do something  amazing with the util ... then
setTimeout(() => {
  // clear the utility or don't reference it anymore anywhere
  util = null;
  // once the GC kicks in, the module.js will log how many
  // utilities are still around and never collected
});