LFades state implementation.

.js

import { useEffect, useRef, useState } from "react";

let atomCount = 0;

export function atom(initialValue) {
    let value = initialValue;
    let subs = [];
    let id = `atom${atomCount++}`;
    return Object.freeze({
        id,
        get() {
            return value;
        },
        set(newValue) {
            if (value === newValue)
                return;
            value = newValue;
            subs.forEach((cb) => {
                cb(value);
            });
        },
        sub(cb) {
            subs.push(cb);
            return () => {
                subs = subs.filter((sub) => sub !== cb);
            };
        },
    });
}
export function useAtom(atom) {
    const [_count, rerender] = useState(0);
    useSubscribe(atom, () => rerender((c) => c + 1));
    return [atom.get(), atom.set];
}
export function useSubscribe(atom, cb, deps = []) {
    useEffect(() => atom.sub(cb), [atom, ...deps]);
}
var HydrateState;
(function (HydrateState) {
    HydrateState[HydrateState["Pending"] = 0] = "Pending";
    HydrateState[HydrateState["Done"] = 1] = "Done";
    HydrateState[HydrateState["Effect"] = 2] = "Effect";
})(HydrateState || (HydrateState = {}));
export function useHydrate(cb, deps) {
    const hydratedRef = useRef(HydrateState.Pending);
    // Hydrate immediately for SSR and for the first render in the browser, this
    // should avoid hydration mismatches.
    if (hydratedRef.current === HydrateState.Pending) {
        hydratedRef.current = HydrateState.Done;
        cb();
    }
    // This allows bundlers to remove the effect at build time.
    if (typeof window !== "undefined") {
        useEffect(() => {
            // Prevent a double hydration and potential mismatch issues by running the
            // callback only from the second render onwards.
            if (hydratedRef.current === HydrateState.Done) {
                hydratedRef.current = HydrateState.Effect;
            }
            else {
                cb();
            }
        }, deps);
    }
}