Lazyload Picturefill Background

Responsive background images using Window.matchMedia() and the Intersection Observer API.

This project is inspired by M6Web/picturefill-background

• Lazyload Picturefill Background
  • Getting Started
    • Install
    • JS
    • HTML
    • CSS
    • Change default selectors
  • Browser support
  • License

Getting Started

Install

With npm:

npm install lazyload-picturefill-background

With yarn:

yarn add lazyload-picturefill-background

With CDN:

<script src="https://unpkg.com/[email protected]/dist/lazyload-picturefill-background.min.js"></script>

You can as well clone this repository.

JS

Using ES6 and import

import lazyloadPicturefillBackground from "lazyload-picturefill-background";

new lazyloadPicturefillBackground();

If you are not using babel you can use dist/lazyload-picturefill-background.min.js

<script src="lazyload-picturefill-background.min.js"></script>
<script>
  new lazyloadPicturefillBackground();
</script>

HTML

The .is-lazy selector is optional. Use it if you want to lazyload our .picturefill-background elements.

<div class="picturefill-background is-lazy">
  <span class="picturefill-background-source" data-src="small.jpg"></span>
  <span
    class="picturefill-background-source"
    data-src="medium.jpg"
    data-media="(min-width: 400px)"
  ></span>
  <span
    class="picturefill-background-source"
    data-src="large.jpg"
    data-media="(min-width: 640px)"
  ></span>
  <span
    class="picturefill-background-source"
    data-src="big.jpg"
    data-media="(min-width: 800px)"
  ></span>
</div>

By default:

• .picturefill-background: apply the background-image attribute
• .is-lazy: Set observer to lazyload the image (Optional)
• .picturefill-background-source:
  • [data-src]: specify the image path
  • [data-media]: apply in specific media settings (Optional)

CSS

Set your CSS as you need:

.picturefill-background {
  background-size: cover;
  background-repeat: no-repeat;
}

.picturefill-background.is-lazy {
  background-color: lime;
}

Change default selectors

import lazyloadPicturefillBackground from "lazyload-picturefill-background";

new lazyloadPicturefillBackground({
  pictureFillBackgroundSelector: ".picturefill-background", //String or node list
  lazySelector: ".is-lazy", //String
  pictureFillBackgroundSourceSelector: ".picturefill-background-source" //String
});

Browser support

Lazyload Picturefill Background will work in all modern browsers. the Intersection Observer API is not supported on IE you can use the w3c polyfill.

The IntersectionObserver polyfill can be included in your project using polyfill.io, which will automatically include dependencies where necessary:

<script src="https://polyfill.io/v3/polyfill.min.js?features=IntersectionObserver"></script>

License

This project is licensed under the MIT License - see the LICENSE file for details