@surface/custom-element/internal/reactivity/data-bind.js

Provides support of directives and data binding on custom elements.

import { setValue } from "@surface/core";
import { scheduler } from "../singletons.js";
import AsyncObserver from "./async-observer.js";
export default class DataBind {
    static observe(target, observables, listener, lazy = false) {
        const subscriptions = observables.map(path => DataBind.oneWay(target, path, listener, lazy));
        return { unsubscribe: () => subscriptions.splice(0).forEach(x => x.unsubscribe()) };
    }
    static oneWay(root, path, listener, lazy = false) {
        const observer = AsyncObserver.observe(root, path, scheduler);
        const subscription = observer.subscribe(listener);
        if (!lazy) {
            observer.notify();
        }
        return subscription;
    }
    static twoWay(left, leftPath, right, rightPath) {
        const leftListener = (value) => setValue(value, right, ...rightPath);
        const rightListener = (value) => setValue(value, left, ...leftPath);
        const leftSubscription = DataBind.oneWay(left, leftPath, leftListener, true);
        const rightSubscription = DataBind.oneWay(right, rightPath, rightListener);
        return [leftSubscription, rightSubscription];
    }
}