49 lines
1.7 KiB
JavaScript
49 lines
1.7 KiB
JavaScript
// Source: https://css-tricks.com/the-complete-guide-to-lazy-loading-images/
|
|
document.addEventListener("DOMContentLoaded", function() {
|
|
var lazyloadImages;
|
|
|
|
if ("IntersectionObserver" in window) {
|
|
lazyloadImages = document.querySelectorAll(".lazy");
|
|
var imageObserver = new IntersectionObserver(function(entries, observer) {
|
|
entries.forEach(function(entry) {
|
|
if (entry.isIntersecting) {
|
|
var image = entry.target;
|
|
image.classList.remove("lazy");
|
|
imageObserver.unobserve(image);
|
|
}
|
|
});
|
|
});
|
|
|
|
lazyloadImages.forEach(function(image) {
|
|
imageObserver.observe(image);
|
|
});
|
|
} else {
|
|
var lazyloadThrottleTimeout;
|
|
lazyloadImages = document.querySelectorAll(".lazy");
|
|
|
|
function lazyload () {
|
|
if(lazyloadThrottleTimeout) {
|
|
clearTimeout(lazyloadThrottleTimeout);
|
|
}
|
|
|
|
lazyloadThrottleTimeout = setTimeout(function() {
|
|
var scrollTop = window.pageYOffset;
|
|
lazyloadImages.forEach(function(img) {
|
|
if(img.offsetTop < (window.innerHeight + scrollTop)) {
|
|
img.src = img.dataset.src;
|
|
img.classList.remove('lazy');
|
|
}
|
|
});
|
|
if(lazyloadImages.length == 0) {
|
|
document.removeEventListener("scroll", lazyload);
|
|
window.removeEventListener("resize", lazyload);
|
|
window.removeEventListener("orientationChange", lazyload);
|
|
}
|
|
}, 20);
|
|
}
|
|
|
|
document.addEventListener("scroll", lazyload);
|
|
window.addEventListener("resize", lazyload);
|
|
window.addEventListener("orientationChange", lazyload);
|
|
}
|
|
});
|