Re-implementing Recoil APIs / article gists

core.ts

// @see https://github.com/NoriSte/recoil-apis

/**
 * Get the current Recoil Atom' value
 */
const coreGetAtomValue = <T>(recoilId: string, atom: Atom<T>): T => {
  const coreRecoilValue = getRecoilStore(recoilId)[atom.key];

  // type-safety
  if (coreRecoilValue.type !== "atom") {
    throw new Error(`${coreRecoilValue.key} is not an atom`);
  }

  return (coreRecoilValue.value as any) as T;
};

/**
 * Get the current Recoil Selector' value
 */
const coreGetSelectorValue = <T>(recoilId: string, selector: Selector<T>): T =>
  selector.get({ get: createPublicGetRecoilValue(recoilId) });

/**
 *  Get the current Recoil Value' value
 */
export const coreGetRecoilValue = <T>(
  recoilId: string,
  recoilValue: RecoilValue<T>
): T =>
  isAtom(recoilValue)
    ? coreGetAtomValue(recoilId, recoilValue)
    : coreGetSelectorValue(recoilId, recoilValue);

/**
 * Create a function that get the current Recoil Value' value
 * @private
 */
export const createPublicGetRecoilValue = <T>(recoilId: string) => (
  recoilValue: RecoilValue<T>
): T => coreGetRecoilValue(recoilId, recoilValue);