sortByKeyTransform.ts

export const keyComparator = <ItemT extends object, ComparableT extends number>(
  keyTransform: (item: ItemT) => ComparableT
) => {
  const _cache = new WeakMap<ItemT, ComparableT>();
  const cachedTransform = (item: ItemT) => {
    if (!_cache.has(item)) {
      _cache.set(item, keyTransform(item));
    }
    return _cache.get(item) as ComparableT;
  };
  return (a: ItemT, b: ItemT) => cachedTransform(a) - cachedTransform(b);
};