Draft of how basic low level Redux filters could work

filter-subscription.js

// ---> custom filtered sub-store

function createContentObservable(store) {
    const contentSubs = {
        X: []
    }

    const dispose = store.subscribe((cat) => {
        if (store.getState().lastAction.type === 'content-change') {
            const id = store.getState().lastAction.id;
            const content = select(store, getContent(id))

            contentSubs[id].forEach(s => s(content))
        }
    });

    return {
        subscribe: (name, cb) => {
            contentSubs[name].push(cb);

            // @todo return unsub
        },
        dispose
    }
}

const contentStore = createContentStore(myStore);
const unSub = contentStore.subscribe('X', (content) => {
    console.log(content);
});
// unSub when needed


// ---> path sub-store

function createPathObservable(path = [], store) {
    const getVal = () => { path.reduce((acc, val) => acc[val], store.getState()) }

    let preValue = getVal()
    const contentSubs = [];

    const dispose = store.subscribe((cat) => {
        const val = getVal();

        if (val !== preValue) {
            contentSubs.forEach(s => s(val));
        }
    });

    return {
        subscribe: (cb) => {
            contentSubs.push(cb);

            // @todo return unsub
        },
        dispose
    }
}

const contentStore = createContentStore(['somereducer', 'some-attribute'], myStore);
const unSub = contentStore.subscribe((content) => {
    console.log(content);
});