document.addEventListener("DOMContentLoaded", function () { let lazyImages = [].slice.call(document.querySelectorAll("img.lazy")); if ("IntersectionObserver" in window) { let lazyImageObserver = new IntersectionObserver(function (entries, observer) { entries.forEach(function (entry) { if (entry.isIntersecting) { let img = entry.target; img.src = img.dataset.src; img.classList.remove("lazy"); lazyImageObserver.unobserve(img); } }); }); lazyImages.forEach(function (lazyImage) { lazyImageObserver.observe(lazyImage); }); } else { lazyImages.forEach(function (img) { img.src = img.dataset.src; }); } });