lazyfunc

grLazyFunc: function(selector, callback) {
            var elem = selector;
            var defaultMargin = '10px';

            let options = {
                rootMargin: defaultMargin
            };

            const imageObserver = new IntersectionObserver((entries, imgObserver) => {
                entries.forEach((entry) => {
                    if (entry.isIntersecting) {
                        const lazyItem = entry.target // Текущий элемент

                        if (callback) {
                            callback();
                        };

                        imgObserver.unobserve(lazyItem);
                    }
                })
            }, options);

            if (typeof selector == 'string') {
                const arr = document.querySelectorAll(elem);
                arr.forEach((v) => {
                    imageObserver.observe(v);
                });
            } else {
                imageObserver.observe(elem);
            };
        },