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‎README.md

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@@ -203,6 +203,16 @@ const coolImage = document.querySelector('.image-to-load-first')
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observer.triggerLoad(coolImage);
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```
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### Large image improvment
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Sometimes image loading takes a long time. For this case, you can add a placeholder background:
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```html
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<img class="lozad" data-placeholder-background="red" data-src="image.png" />
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```
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Lozad sets a placeholder background color of img element and users will see the fallback till the image loads.
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## Example with picture tag
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Create _a broken_ picture element structure.

‎demo/assets/css/main.css

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@@ -47,6 +47,7 @@ body {
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img {
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width: 100%;
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height: 100%;
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}
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/* Box Model */

‎demo/index.html

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@@ -58,62 +58,62 @@ <h1><a href="https://github.com/ApoorvSaxena/lozad.js"><strong>Lozad.js</strong>
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<h1>Lozad.js - Performant Lazy Loading Library</h1>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/01.jpg" data-index="1" />
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<img class="lozad" data-placeholder-background="#583624" data-src="images/thumbs/01.jpg" data-index="1" />
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<noscript><img src="images/thumbs/01.jpg" data-index="1" /></noscript>
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<h2>Image 1</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/02.jpg" data-index="2" />
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<img class="lozad" data-placeholder-background="#b97248" data-src="images/thumbs/02.jpg" data-index="2" />
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<noscript><img src="images/thumbs/02.jpg" data-index="2" /></noscript>
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<h2>Image 2</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/03.jpg" data-index="3" />
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<img class="lozad" data-placeholder-background="#352629" data-src="images/thumbs/03.jpg" data-index="3" />
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<noscript><img src="images/thumbs/03.jpg" data-index="3" /></noscript>
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<h2>Image 3</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/04.jpg" data-index="4" />
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<img class="lozad" data-placeholder-background="#5e7b80" data-src="images/thumbs/04.jpg" data-index="4" />
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<noscript><img src="images/thumbs/04.jpg" data-index="4" /></noscript>
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<h2>Image 4</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/05.jpg" data-index="5" />
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<img class="lozad" data-placeholder-background="#444443" data-src="images/thumbs/05.jpg" data-index="5" />
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<noscript><img src="images/thumbs/05.jpg" data-index="5" /></noscript>
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<h2>Image 5</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/06.jpg" data-index="6" />
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<img class="lozad" data-placeholder-background="#a2a8ab" data-src="images/thumbs/06.jpg" data-index="6" />
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<noscript><img src="images/thumbs/06.jpg" data-index="6" /></noscript>
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<h2>Image 6</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/07.jpg" data-index="7" />
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<img class="lozad" data-placeholder-background="#3e5e79" data-src="images/thumbs/07.jpg" data-index="7" />
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<noscript><img src="images/thumbs/07.jpg" data-index="7" /></noscript>
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<h2>Image 7</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/08.jpg" data-index="8" />
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<img class="lozad" data-placeholder-background="#32141d" data-src="images/thumbs/08.jpg" data-index="8" />
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<noscript><img src="images/thumbs/08.jpg" data-index="8" /></noscript>
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<h2>Image 8</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/09.jpg" data-index="9" />
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<img class="lozad" data-placeholder-background="#67848a" data-src="images/thumbs/09.jpg" data-index="9" />
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<noscript><img src="images/thumbs/09.jpg" data-index="9" /></noscript>
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<h2>Image 9</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/10.jpg" data-index="10" />
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<img class="lozad" data-placeholder-background="#322721" data-src="images/thumbs/10.jpg" data-index="10" />
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<noscript><img src="images/thumbs/10.jpg" data-index="10" /></noscript>
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<h2>Image 10</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/11.jpg" data-index="11" />
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<img class="lozad" data-placeholder-background="#c8c3c4" data-src="images/thumbs/11.jpg" data-index="11" />
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<noscript><img src="images/thumbs/11.jpg" data-index="11" /></noscript>
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<h2>Image 11</h2>
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</article>
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<article class="thumb">
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<img class="lozad" data-src="images/thumbs/12.jpg" data-index="12" />
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<img class="lozad" data-placeholder-background="#5a6840" data-src="images/thumbs/12.jpg" data-index="12" />
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<noscript><img src="images/thumbs/12.jpg" data-index="12" /></noscript>
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<h2>Image 12</h2>
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</article>

‎dist/lozad.es.js

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@@ -83,6 +83,12 @@ function markAsLoaded(element) {
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element.setAttribute('data-loaded', true);
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}
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function preLoad(element) {
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if (element.getAttribute('data-placeholder-background')) {
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element.style.background = element.getAttribute('data-placeholder-background');
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}
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}
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const isLoaded = element => element.getAttribute('data-loaded') === 'true';
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const onIntersection = (load, loaded) => (entries, observer) => {
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});
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}
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const elements = getElements(selector, root);
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for (let i = 0; i < elements.length; i++) {
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preLoad(elements[i]);
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}
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return {
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observe() {
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const elements = getElements(selector, root);

‎dist/lozad.js

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element.setAttribute('data-loaded', true);
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}
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function preLoad(element) {
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if (element.getAttribute('data-placeholder-background')) {
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element.style.background = element.getAttribute('data-placeholder-background');
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}
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}
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var isLoaded = function isLoaded(element) {
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return element.getAttribute('data-loaded') === 'true';
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};
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});
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}
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var elements = getElements(selector, root);
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for (var i = 0; i < elements.length; i++) {
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preLoad(elements[i]);
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}
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return {
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observe: function observe() {
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var elements = getElements(selector, root);
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for (var i = 0; i < elements.length; i++) {
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if (isLoaded(elements[i])) {
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for (var _i = 0; _i < elements.length; _i++) {
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if (isLoaded(elements[_i])) {
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continue;
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}
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if (observer) {
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observer.observe(elements[i]);
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observer.observe(elements[_i]);
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continue;
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}
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load(elements[i]);
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markAsLoaded(elements[i]);
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loaded(elements[i]);
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load(elements[_i]);
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markAsLoaded(elements[_i]);
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loaded(elements[_i]);
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}
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},
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triggerLoad: function triggerLoad(element) {

‎dist/lozad.min.js

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‎src/lozad.js

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element.setAttribute('data-loaded', true)
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}
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function preLoad(element) {
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if (element.getAttribute('data-placeholder-background')) {
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element.style.background = element.getAttribute('data-placeholder-background')
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}
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}
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const isLoaded = element => element.getAttribute('data-loaded') === 'true'
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const onIntersection = (load, loaded) => (entries, observer) => {
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})
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}
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const elements = getElements(selector, root)
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for (let i = 0; i < elements.length; i++) {
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preLoad(elements[i])
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}
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return {
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observe() {
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const elements = getElements(selector, root)

‎test/index.js

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'background-image: url(photo.jpg);'
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)
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})
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// Handle image background placeholder
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it('should load the image with data-placeholder-background attribute', () => {
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const image = document.querySelectorAll('img')[0]
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const bgImageSetAttr = 'red'
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image.setAttribute('class', 'lozad')
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image.setAttribute('data-placeholder-background', bgImageSetAttr)
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const observer = lozad()
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observer.observe()
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assert.strictEqual('true', image.dataset.loaded)
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assert.strictEqual(image.style.cssText, 'background: red;')
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})
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})
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describe('when passing options', () => {

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