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lozad.es.js
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lozad.es.js
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/*! lozad.js - v1.15.0 - 2020-08-01
* https://github.com/ApoorvSaxena/lozad.js
* Copyright (c) 2020 Apoorv Saxena; Licensed MIT */
/**
* Detect IE browser
* @const {boolean}
* @private
*/
const isIE = typeof document !== 'undefined' && document.documentMode;
const defaultConfig = {
rootMargin: '0px',
threshold: 0,
load(element) {
if (element.nodeName.toLowerCase() === 'picture') {
const img = document.createElement('img');
if (isIE && element.getAttribute('data-iesrc')) {
img.src = element.getAttribute('data-iesrc');
}
if (element.getAttribute('data-alt')) {
img.alt = element.getAttribute('data-alt');
}
element.append(img);
}
if (element.nodeName.toLowerCase() === 'video' && !element.getAttribute('data-src')) {
if (element.children) {
const childs = element.children;
let childSrc;
for (let i = 0; i <= childs.length - 1; i++) {
childSrc = childs[i].getAttribute('data-src');
if (childSrc) {
childs[i].src = childSrc;
}
}
element.load();
}
}
if (element.getAttribute('data-poster')) {
element.poster = element.getAttribute('data-poster');
}
if (element.getAttribute('data-src')) {
element.src = element.getAttribute('data-src');
}
if (element.getAttribute('data-srcset')) {
element.setAttribute('srcset', element.getAttribute('data-srcset'));
}
let backgroundImageDelimiter = ',';
if (element.getAttribute('data-background-delimiter')) {
backgroundImageDelimiter = element.getAttribute('data-background-delimiter');
}
if (element.getAttribute('data-background-image')) {
element.style.backgroundImage = `url('${element.getAttribute('data-background-image').split(backgroundImageDelimiter).join('\'),url(\'')}')`;
} else if (element.getAttribute('data-background-image-set')) {
const imageSetLinks = element.getAttribute('data-background-image-set').split(backgroundImageDelimiter);
let firstUrlLink = (imageSetLinks[0].substr(0, imageSetLinks[0].indexOf(' ')) || imageSetLinks[0]); // Substring before ... 1x
firstUrlLink = firstUrlLink.indexOf('url(') === -1 ? `url(${firstUrlLink})` : firstUrlLink;
if (imageSetLinks.length === 1) {
element.style.backgroundImage = firstUrlLink;
} else {
element.setAttribute('style', (element.getAttribute('style') || '') + `background-image: ${firstUrlLink}; background-image: -webkit-image-set(${imageSetLinks}); background-image: image-set(${imageSetLinks})`);
}
}
if (element.getAttribute('data-toggle-class')) {
element.classList.toggle(element.getAttribute('data-toggle-class'));
}
},
loaded() {}
};
function markAsLoaded(element) {
element.setAttribute('data-loaded', true);
}
function preLoad(element) {
if (element.getAttribute('data-placeholder-background')) {
element.style.background = element.getAttribute('data-placeholder-background');
}
}
const isLoaded = element => element.getAttribute('data-loaded') === 'true';
const onIntersection = (load, loaded) => (entries, observer) => {
entries.forEach(entry => {
if (entry.intersectionRatio > 0 || entry.isIntersecting) {
observer.unobserve(entry.target);
if (!isLoaded(entry.target)) {
load(entry.target);
markAsLoaded(entry.target);
loaded(entry.target);
}
}
});
};
const getElements = (selector, root = document) => {
if (selector instanceof Element) {
return [selector]
}
if (selector instanceof NodeList) {
return selector
}
return root.querySelectorAll(selector)
};
function lozad (selector = '.lozad', options = {}) {
const {root, rootMargin, threshold, load, loaded} = Object.assign({}, defaultConfig, options);
let observer;
if (typeof window !== 'undefined' && window.IntersectionObserver) {
observer = new IntersectionObserver(onIntersection(load, loaded), {
root,
rootMargin,
threshold
});
}
const elements = getElements(selector, root);
for (let i = 0; i < elements.length; i++) {
preLoad(elements[i]);
}
return {
observe() {
const elements = getElements(selector, root);
for (let i = 0; i < elements.length; i++) {
if (isLoaded(elements[i])) {
continue
}
if (observer) {
observer.observe(elements[i]);
continue
}
load(elements[i]);
markAsLoaded(elements[i]);
loaded(elements[i]);
}
},
triggerLoad(element) {
if (isLoaded(element)) {
return
}
load(element);
markAsLoaded(element);
loaded(element);
},
observer
}
}
export default lozad;