gistfile1.txt

const reducers = combineReducers({
    routing,
    chapters: (state = {}) => state,
    expandChapter
});

export default reducers;


const expandChapter = (state = {}, action = null) => {

    if(action.type == EXPAND_CHAPTER) {
        var item = state[action.id];
        return {...item, isExpanded: !item.isExpanded}
    }
    return state;
};

export  {
    expandChapter
}