Reuse the same redux reducer code for a different slice of state

createNamedReducer.js

/**
 * Higher-order reducer factory for creating named reducers.
 * Both params are required, and it will return your reducer or state.
 *
 * @param key
 * @param reducer
 * @returns {function}
 */
const createNamedReducer = (key, reducer) => {
	return (state, action) => {
		// Action must have a key called 'reducerName'. Use the optional metadata param with createAction
		const { reducerName } = action;
		const isInitialCall = state === undefined; // Check if initialization is happening

		// If the provided key doesn't match the reducerName, and it's not the initialization, return the state
		if (reducerName !== key && !isInitialCall) {
			return state;
		}

		// Otherwise return the reducer
		return reducer(state, action);
	};
};

export default createNamedReducer;

usage.js

const reducers = {
  someOtherReducer,
  [SLICE_1]: createNamedReducer(SLICE_1, reducer),
  [SLICE_2]: createNamedReducer(SLICE_2, reducer),
  [SLICE_3]: createNamedReducer(SLICE_3, reducer)
};