export const uniqueBy = <T, K>(
  arr: readonly T[],
  getKey: (item: T) => K,
): T[] => {
  const map = new Map<K, T>();
  for (const item of arr) {
    map.set(getKey(item), item);
  }
  return [...map.values()];
};

// Usage
const users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' },
  { id: 1, name: 'Alice (updated)' },
];

uniqueBy(users, u => u.id);
// [{ id: 1, name: 'Alice (updated)' }, { id: 2, name: 'Bob' }]