index.js.flow

/**
 * Copyright 2004-present Facebook. All Rights Reserved.
 *
 * @flow
 * @format
 */

// This comes straight from the Redux types.
type ActionType = {+type: string & any};

export type ReduxReactHooks<
  TState,
  TAction: ActionType,
  TDispatch,
  TStore: Store<TState, TAction, TDispatch>,
> = {|
  +StoreContext: Context<?TStore>,
  +useMappedState: <TResult>(
    mapState: (state: TState) => TResult,
    equalityCheck?: (TResult, TResult) => boolean,
  ) => TResult,
  +useDispatch: () => TDispatch,
|};

type CreateOptions = {|
  defaultEqualityCheck?: (a: mixed, b: mixed) => boolean,
|};

/**
 * To use redux-react-hook with stronger type safety, or to use with multiple
 * stores in the same app, create() your own instance and re-export the returned
 * functions.
 */
declare export function create<
  TState,
  TAction: ActionType,
  TDispatch,
  TStore: Store<TState, TAction, TDispatch>,
>(options?: CreateOptions): ReduxReactHooks<TState, TAction, TDispatch, TStore>;

// This is a module variable, so it cannot be typed generic.
declare export var StoreContext: Context<any>;

declare export function useDispatch<TDispatch>(): TDispatch;

/**
 * Your passed in mapState function should be memoized with useCallback to avoid
 * resubscribing every render. If you don't use other props in mapState, pass
 * an empty array [] as the dependency list so the callback isn't recreated
 * every render.
 *
 * const todo = useMappedState(useCallback(
 *   state => state.todos.get(id),
 *   [id],
 * ));
 */
declare export function useMappedState<TState, TResult>(
  mapState: (state: TState) => TResult,
  equalityCheck?: (TResult, TResult) => boolean,
): TResult;