Basic Memoized Selector Creation

import { createSelector } from '@reduxjs/toolkit';

// Selector to get the items array from state
const selectCartItems = state => state.cart.items;

// Memoized selector to calculate the total price of items in the shopping cart
const selectTotalPrice = createSelector(
  [selectCartItems],
  (items) => items.reduce((total, item) => total + item.price * item.quantity, 0)
);