redux_post_h_proxy.js

const combineLazyReducers = (reducers, initialState) => {
    initialState = initialState || {};
    let handler = {
        ownKeys(target){
            return Array.from(new Set([...Reflect.ownKeys(target), ...Reflect.ownKeys(initialState)]));
        },
        get(target, key){
            return target[key] || (state => state === undefined ? null : state);
        },
        getOwnPropertyDescriptor(target, key){
            return Reflect.getOwnPropertyDescriptor(target, key) || Reflect.getOwnPropertyDescriptor(initialState, key);
        }
    };

    return combineReducers(new Proxy(reducers, handler));
}