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Fix lazy loading of images in CmsSlot. #93

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Merged
merged 1 commit into from
Jun 1, 2020
Merged

Fix lazy loading of images in CmsSlot. #93

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2 changes: 1 addition & 1 deletion src/CmsSlot.js
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ export const styles = theme => ({
left: 0,
},
},
'& img[data-rsf-lazy]': {
'& img[data-src]': {
visibility: 'hidden',
},
},
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15 changes: 12 additions & 3 deletions src/utils/lazyLoadImages.js
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Expand Up @@ -4,16 +4,25 @@
* attribute is copied to `src`.
*
* See https://developers.google.com/web/fundamentals/performance/lazy-loading-guidance/images-and-video/
* @param {DOMElement} element The img element to lazy load
* @param {Object} options
* @param {Object} options.lazySrcAttribute The attribute containing the image URL. Defaults to `data-src`.
*/
export default function lazyLoadImages(element, { selector = 'img[data-rsf-lazy]' } = {}) {
export default function lazyLoadImages(element, { lazySrcAttribute = 'data-src' } = {}) {
if (!element) return
const lazyImages = [...element.querySelectorAll(selector)]
const lazyImages = [...element.querySelectorAll(`img[${lazySrcAttribute}]`)]
if (!lazyImages.length) return

let lazyImageObserver

const load = img => {
img.src = img.dataset.src
const src = img.getAttribute(lazySrcAttribute)
const onload = () => {
img.removeAttribute(lazySrcAttribute)
img.removeEventListener('load', onload)
}
img.addEventListener('load', onload)
img.setAttribute('src', src)

if (lazyImageObserver) {
lazyImageObserver.disconnect(img)
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10 changes: 5 additions & 5 deletions test/utils/lazyLoadImages.test.js
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Expand Up @@ -12,7 +12,7 @@ describe('lazyLoadImages', () => {

return (
<div ref={ref}>
<img ref={imageRef} data-src="https://via.placeholder.com/600x600" data-rsf-lazy="1" />
<img ref={imageRef} data-src="https://via.placeholder.com/600x600" />
</div>
)
}
Expand All @@ -38,7 +38,7 @@ describe('lazyLoadImages', () => {
})

it('should do nothing if selector can not find anything', () => {
selector = { selector: 'test' }
selector = { lazySrcAttribute: 'data-lazy-src' }

wrapper = mount(<Test />)

Expand All @@ -53,10 +53,10 @@ describe('lazyLoadImages', () => {
// Not intersected
observer.simulateChange(0, imageRef.current)
expect(ref.current.src).toBeUndefined()

observer.simulateChange(1, imageRef.current)

expect(imageRef.current.src).toBe('https://via.placeholder.com/600x600')
expect(imageRef.current.getAttribute('src')).toBe('https://via.placeholder.com/600x600')
imageRef.current.dispatchEvent(new Event('load'))
expect(imageRef.current.getAttribute('data-src')).toBe(null)
})

describe('if intersection observer is not available', () => {
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