lazyload.html

<!--
https://developers.google.com/web/fundamentals/performance/lazy-loading-guidance/images-and-video/
https://css-tricks.com/preventing-content-reflow-from-lazy-loaded-images/
https://codepen.io/tigt/post/optimizing-svgs-in-data-uris
https://addyosmani.com/blog/lazy-loading/
-->
<img
  alt="A cat"
  class="lazyload"
  data-src="cat.jpg"
  loading="lazy"
  src="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 1440 900'%3E%3C/svg%3E"
>
<noscript>
  <img alt="A cat" src="cat.jpg">
</noscript>