Method indexBy

packages/core/src/entity/Collection.ts:840–848

* Maps the collection items to a dictionary, indexed by the key you specify. * If there are more items with the same key, only the first one will be present.

(
    key: K1,
    valueKey?: K2,
  )

   * If there are more items with the same key, only the first one will be present.
   */
  indexBy<K1 extends keyof T, K2 extends keyof T = never>(
    key: K1,
    valueKey?: K2,
  ): Record<T[K1] & PropertyKey, T> | Record<T[K1] & PropertyKey, T[K2]> {
    return this.reduce((obj, item) => {
      obj[item[key] as string] ??= valueKey ? item[valueKey] : item;
      return obj;
    }, {} as any);
  }

  /** Returns whether the collection has been initialized. Pass `fully = true` to also check that all items are initialized. */
  isInitialized(fully = false): boolean {