const initialState = { devices: [], positions: [], events: [] }; function rootReducer(state = initialState, action) { switch (action.type) { case 'UPDATE_DEVICES': return Object.assign({}, { ...state, devices: [...action.devices] }); case 'UPDATE_POSITIONS': return Object.assign({}, { ...state, positions: [...action.positions] }); default: return state; } } export default rootReducer