number-munchers/js/app/Reducers.js

import { MODE, ACTIONS } from './Constants.js';

export const modeReducer = (state = MODE.WELCOME, action) => {
    if (action.type === ACTIONS.NEXT) {
        switch (state) {
            case MODE.BOARD:
                return MODE.WELCOME;
            case MODE.WELCOME:
                return MODE.BOARD;
        };
    }
    else {
        return MODE.WELCOME;
    }
};