https://giubberossenews.it/wp-content/plugins/featured-image-from-url/includes/html/js/lazyload.js?ver=6.0.9

1document.addEventListener("DOMContentLoaded", function () {
2    let lazyImages = document.querySelectorAll("img[fifu-lazy='1']");
3
4    function setSizesAttribute(image) {
5        if (image.getAttribute('fifu-data-sizes') === 'auto') {
6            let width = image.getAttribute('width') || image.clientWidth;
7            image.setAttribute('sizes', `${width}px`);
8        }
9    }
10
11    if ("IntersectionObserver" in window) {
12        let lazyImageObserver = new IntersectionObserver(function (entries, observer) {
13            entries.forEach(function (entry) {
14                if (entry.isIntersecting) {
15                    let lazyImage = entry.target;
16                    lazyImage.src = lazyImage.getAttribute('fifu-data-src');
17                    lazyImage.srcset = lazyImage.getAttribute('fifu-data-srcset');
18                    setSizesAttribute(lazyImage);
19                    lazyImage.removeAttribute('fifu-lazy');
20                    lazyImageObserver.unobserve(lazyImage);
21                }
22            });
23        });
24
25        lazyImages.forEach(function (lazyImage) {
26            lazyImageObserver.observe(lazyImage);
27        });
28    } else {
29        // Fallback for browsers that do not support IntersectionObserver
30        let lazyLoadThrottleTimeout;
31
32        function debounce(func, wait) {
33            return function () {
34                clearTimeout(lazyLoadThrottleTimeout);
35                lazyLoadThrottleTimeout = setTimeout(func, wait);
36            };
37        }
38
39        function lazyLoad() {
40            let scrollTop = window.scrollY;
41            lazyImages.forEach(function (img) {
42                if (img.offsetTop < (window.innerHeight + scrollTop)) {
43                    img.src = img.getAttribute('fifu-data-src');
44                    img.srcset = img.getAttribute('fifu-data-srcset');
45                    setSizesAttribute(img);
46                    img.removeAttribute('fifu-lazy');
47                }
48            });
49            lazyImages = Array.prototype.filter.call(lazyImages, function (img) {
50                return img.hasAttribute('fifu-lazy');
51            });
52            if (lazyImages.length == 0) {
53                document.removeEventListener("scroll", lazyLoadHandler);
54                window.removeEventListener("resize", lazyLoadHandler);
55                window.removeEventListener("orientationchange", lazyLoadHandler);
56            }
57        }
58
59        let lazyLoadHandler = debounce(lazyLoad, 20);
60
61        document.addEventListener("scroll", lazyLoadHandler);
62        window.addEventListener("resize", lazyLoadHandler);
63        window.addEventListener("orientationchange", lazyLoadHandler);
64    }
65}, {once: true});