storable-state/dist/store/derived.js

State management library that integrates with localStorage

import Store from './store.js';
export default (dependencies, update) => {
    const store = new Store();
    const values = [];
    const subMap = new Map();
    if (dependencies instanceof Array) {
        dependencies.forEach((dependency, i) => {
            subMap.set(i, value => {
                values[i] = value;
                if (values.length === dependencies.length)
                    store.set(update(...values));
            });
            dependency.subscribe(subMap.get(i));
        });
    }
    else {
        dependencies.subscribe(value => store.set(update(value)));
    }
    return { subscribe: store.subscribe };
};