react selectors code example
Example: selector for redux
import { createSelector } from 'reselect';
const getProducts = state => state.products.itemsById;
const getCartItemIds = state => state.currentUser.shoppingCart.itemIds;
export const selectShoppingCartItems = createSelector(
getProducts,
getCartItemIds,
(products, itemIds) => itemIds.map(id => products[id])
);