peschee / lazy-image

Lazily load your images with <lazy-image> custom element

<lazy-image>

Lazily load your images!

🚛 Get it!

npm -i -S @power-elements/lazy-image

📦 Load it!

<!-- From CDN -->
<script async type="module" src="https://unpkg.com/@power-elements/lazy-image/lazy-image.js"></script>

<!-- From local installation -->
<script async type="module" src="/node_modules/@power-elements/lazy-image/lazy-image.js"></script>

<!-- In a Module -->
<script type="module">
  import '/node_modules/@power-elements/lazy-image/lazy-image.js';
  // ...
</script>

💪 Use it!

<lazy-image src="image.jpg" alt="Lazy Image">
  <svg slot="placeholder"><use xlink:href="#placeholder-svg"></use></svg>
</lazy-image>

The optional placeholder could be any element. Inline SVG, Pure CSS graphics, or an <img src="data:foo"/> would work best.

💄 Style it!

You should give your <lazy-image> elements some specific dimensions, since it absolutely positions its shadow children. In most cases, you should set the wrapping element as well as the --lazy-image- custom properties to the known display dimensions of your image.

<style>
html {
  --lazy-image-width: 640px;
  --lazy-image-height: 480px;
}

lazy-image {
  width: var(--lazy-image-width);
  height: var(--lazy-image-height);
}
</style>

<lazy-image src="https://fillmurray.com/640/480"></lazy-image>

<lazy-image> exposes a set of custom properties for your customizing delight:

Property	Purpose	Default
--lazy-image-width	Width of the internal image and placeholder elements	100%
--lazy-image-height	Height of the internal image and placeholder elements	100%
--lazy-image-fit	object-fit property of the internal image and placeholder elements	contain
--lazy-image-fade-duration	Duration of the fade in from the placeholder to the image. Set to 0 to disable fading.	0.3s
--lazy-image-fade-easing	ease property of the opacity transition for the image and placeholder	ease

Browser support

lazy-image manages the loading of your images via an Intersection Observer. In browsers where an Intersection Observer is not present, your images will be loaded immediately much like standard <img/> elements. Conditionally delivering the IntersectionObserver polyfill along with your lazy-images to your users will ensure that all users experience the benefits of loading images lazily. Stay lazy, friend!