bodega.js

const initialToDoState = {
  toDos: [],
};

const ADDTODO = { 
  type: 'ADD_TODO',
  toDo: ''
};

const toDoReducer = (state = initialToDoState, action) => {
  switch(action.type) {
    case 'ADD_TODO':
      // spread the current state and toDos array to save prior changes
      // add the new toDo to the toDos array
      return {
        ...state,
        toDos: [
          // spread the array as it's nested
          ...state.toDos,
          action.payload.toDo,
        ],
      };
      
    // default catch in case an action doesn't exist
    // this will return the initialState
    default:
      return state;
  };
};

const store = Redux.createStore(toDoReducer, initialToDoState);