reducer.js

import * as types from './types';

export const initialState = {
  msg: ''
};

export default (state = initialState, action) => {
  switch (action.type) {
    case types.TRY_SUBMIT:
      return trySubmit(state);

    case types.SUBMIT_SUCCESS:
      return submitSuccess(state, action);

    case types.SUBMIT_FAILURE:
      return submitFailure(state, action);

    
    default:
      return state;
  }
};

function trySubmit(state) {
  return {...state, msg: '' };
}

function submitSuccess(state, action) {
  return {...state, msg: action.msg };
}

function submitFailure(state, action) {
  return {...state, msg: action.msg };
}