Image simple lazy Loader with SEO enhancement

main.js

/**
 * Simple Image Lazy Loader
 * @author: Robin D. https://www.robin-d.fr/
 * idea borrow from : https://davidwalsh.name/lazyload-image-fade
 * Example : <span data-img="https://source.unsplash.com/collection/993239/600x400">Random Image from Unsplash</span>
 * will be transform to : <img src="https://source.unsplash.com/collection/993239/600x400" alt="Random Image from Unsplash" />
 */
export function imgLazyLoad() {
    [].forEach.call(document.querySelectorAll('[data-img]'), function(img) {
        let newDomImg = document.createElement('img');
        let src = img.getAttribute('data-img');
        img.removeAttribute('data-img');
        for (var i = 0, n = img.attributes.length; i < n; i++){
          newDomImg.setAttribute(img.attributes[i].nodeName, img.attributes[i].nodeValue);
        }
        if (newDomImg.getAttribute('alt') === null && img.textContent != '') {
            newDomImg.setAttribute('alt', img.textContent);
        }
        newDomImg.setAttribute('src', src);
        img.outerHTML = newDomImg.outerHTML;

    });
}

Test with delay (npm) : http://localhost:4567/5000/https://source.unsplash.com/collection/993239/600x400

#SEO tip :

<a href="my-image" data-img="my-image">my image</a>