1.jsx

function reducer(state = {books: []}, action) {
  switch (action.type) {
    case "SET_RECOMMENDED":
      return {books: action.payload};
    default:
      state;
  }
}

function mapStateToPros(state) {
  console.log("state: "+state);
  return {books: state.books};
}

const store = createStore(reducer, {books: []});