Redux toolkit in vanilla JavaScript - reducer has too much responsibility

Question

I am creating a slice with a reducer that selects an entity by id.

Only one entity must be selected at a time, so the reducer deselects any previously selected entity, before selecting the new one.

I am maintaining the id of the selected item in state.

This does not 'feel' right, as the reducer is changing three things:

• Deselects previously selected entity
• Selects the new entity
• Sets the state.selectedItemId to the newly selected entity id

Can anyone suggest a better way to achieve this?

const itemsAdapter = createEntityAdapter();

const itemsSlice = createSlice({
    name: 'items',
    initialState: itemsAdapter.getInitialState({
        selectedItemId: null
    }),
    reducers: {
        itemSelected: (state, action) => {
            if (state.selectedItemId) {
                state.entities[state.selectedItemId].selected = false;
            }
            state.entities[action.payload].selected = true;
            state.selectedItemId = action.payload;
        }
    }
});