redux-02.js

// action types
// import types from 'actionTypes.js'

function accounts(state = [], action) {
  switch(action.type) {
    case types.ADD_ACCOUNT:
      return [
          ...state,
          {
            id: getNewId(), //fake method that returns new ID
            title: action.title,
            createdBy: action.createdBy
          }
        ];
    case types.DELETE_ACCOUNT:
      return deleteAccountByID(action.id); //fake method that returns new array of accounts without specified one
    default:
      return state;
  }
}