Observer.js

 window.Observer = {

    observer: null,

    Initialize: function (component, observerTargetId) {

        this.observer = new IntersectionObserver(e => {

            component.invokeMethodAsync('OnIntersection');

        });

        let element = document.getElementById(observerTargetId);

        if (element == null) throw new Error("Target was not found");

        this.observer.observe(element);

    }

};