I am refactoring my code to eliminate the default store and use ES6+ defaults as follows:

That is I am moving defaults from an object passed in as follows:

const store = createStore(reducers, defaultstore, middleware);

to directly into the reducers. This way I can locate them easier. The two methods are shown below ...

defaultstore

  Menu: {
    current: 'Articles'
  },

reducer function

// People is the default
const Menu = (state = {current: 'People'}, action) => {
  const newState = { ...state };
  switch(action.type) {
  case 'updateMenu':
    newState.current = action.current;
    return newState;
  }
  return state;
};

Is there any reason not to do this. It makes the code more readable.