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progressive-image.js

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  • License MIT

progressive lazy-loading image system

Package Exports

  • progressive-image.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (progressive-image.js) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

progressive-image.js

demonstration | GitHub | npm | donate | @craigbuckler | craigbuckler.com

progressive-image.js implements a progressively-loaded image effect similar to those seen on Facebook and Medium. A very small blurred image is replaced with the full-resolution equivalent when the element is scrolled into view.

Please use the code as you wish. Tweet me @craigbuckler if you find it useful and consider donating toward development.

Benefits:

  • saves unnecessary bandwidth
  • fast loading, high performance, images loaded on view
  • supports any image type (JPEG photographs are most appropriate)
  • supports responsive images (srcset and sizes attributes)
  • supports CSS background images
  • supports native lazy loading and aspect ratios
  • lightweight: 1,407 bytes of JavaScript, 407 bytes of optional CSS (minified)
  • any CSS reveal effect can be applied
  • no external dependencies - works with any framework
  • makes up to three attempts if images fail to download
  • works in all modern browsers (IE10+)
  • progressively-enhanced to work in older browsers
  • easy to use

View demonstration and full documentation...

Basic usage

Include the minified CSS and JavaScript anywhere in your page:

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/progressive-image.js/dist/progressive-image.css">
<script src="https://cdn.jsdelivr.net/npm/progressive-image.js/dist/progressive-image.js" async></script>

or use npm and a bundler:

npm i progressive-image.js

Then add progressively-loaded images:

<a href="full.jpg" class="progressive replace">
  <img src="tiny.jpg" class="preview" alt="image" />
</a>

where:

  • full.jpg is the large image.
  • tiny.jpg is a small preview image - typically 20px width.

Both images must have the same aspect ratio.

Refer to demo.html for full documentation, examples, options, and usage notes. It is also available as a CodePen demonstration page.

Version history

v1.6.1, 2 October 2021

  • fixed page resize removing responsive srcset images

v1.6.0, 3 July 2020

  • improved browser support verification
  • more resilient to framework issues
  • minor refactoring
  • updated help and images
  • bugfix: script now works in HTML <head>

v1.5.0, 6 June 2020

  • pageshow event for Single Page Apps
  • more reliable MutationObserver
  • class names applied to the preview are applied to the full image (except preview)
  • smaller, better performance
  • no errors in older browsers
  • updated usage notes, including native lazy loading

v1.4.1, 9 July 2019

  • strict mode
  • srcset and sizes attributes only set when available
  • README and demo.html update

v1.4.0, 24 June 2019

  • retries download after 3s and 6s (suggestion from cheuksing)
  • continues to show preview if full image download fails
  • autoprefixer update

v1.3.0, 30 May 2019

  • Gulp.js minification
  • published on npm, CDN information

v1.2.0, 13 April 2018

  • added CSS background image support information

v1.2.0, 9 April 2018

  • full image replaces preview in-place (PR from ftaiolivista)
  • minor refactoring and simplification

v1.1.0, 25 November 2017

  • permits any container element
  • link to other URLs can be retained
  • mutation observer event detects elements added via JavaScript
  • minor performance tweaks

v1.0.0, 16 January 2017

  • Initial commit