AB-interchange

AB-interchange is a small, dependency free and vanilla script to:

lazy load images and background-images
give responsiveness to background-images

It's damn small: about 2.6KB (uglyfied and GZipped).

Have a look at this Demonstration page (offline version in the docs folder).

Version 1 is used on French websites of ENGIE and Gaz tarif règlementé.

Important news

removed <img> and <picture> support since it's natif and useless on IE 11.
removed delayed option that was quite useless and introduced code complexity

Install

npm install --save ab-interchange

Setup

Import it in your JS bundle (webpack, ES6, browserify…):

import abInterchange from 'ab-interchange';

(If you are not building your assets, simply load the script AB-interchange.min.js in the dist folder.)

Usage

Follow AB-mediaQuery readme file to configure it the way you like depending on your needs. For exemple:

AB.plugins.mediaQuery({
  bp: {
    smallOnly:  'screen and (max-width: 767px)',
    mediumOnly: 'screen and (min-width: 768px) and (max-width: 1024px)',
    medium:     'screen and (min-width: 768px)',
    largeOnly:  'screen and (min-width: 1025px) and (max-width: 1280px)',
    large:      'screen and (min-width: 1025px)'
  }
});

Then initialize interchange with some options.

AB.plugins.interchange({
  mode: 'lazy-img',
  lazySettings: {
    offscreen: 1.25,
    layout:    'fluid' // can be "fixed" to fixed dimensions (not fluid)
  }
});

mode can be:
- lazy-img
- background
- lazy-background
lazySettings are for lazy modes:
- offscreen: load picture only when in the viewport * offscreen value
- layout: Can be fluid (default) for fluid images or fixed for fixed dimensions

Use data-ab-interchange attribute to pass specific options on an element if needed.

data-ab-interchange-src attribute is where you define different sources and breakpoints defined with AB-mediaQuery. It should contain a list of arrays with the path to the asset and the breakpoint name. Beware to respect mobile first order. Order is VERY important!

Examples

Lazy loading of img

<div
  alt=""
  width="100"
  height="75"
  data-ab-interchange='{
    "mode": "lazy-img",
    "lazySettings": {
      "offscreen": 1,
    }
  }"'
  data-ab-interchange-src="[xxx, smallOnly], [xxx, medium]">
</div>

If your images have different ratio depending on media query you can provide a JSON on width and height attributes:

width='{"smallOnly": 20, "medium": 50}'
height='{"smallOnly": 20, "medium": 50}'

background-image

<div
  data-ab-interchange='{"mode": "background"}'
  data-ab-interchange-src="[xxx, smallOnly], [xxx, medium]">
</div>

Lazy load background-image

<div
  data-ab-interchange='{"mode": "lazy-background"}'
  data-ab-interchange-src="[xxx, smallOnly], [xxx, medium]">
</div>

JS event

replaced.ab-interchange event is automatically triggered when when an image/background-image update.

window.addEventListener('replaced.ab-interchange', function(e){
  console.log(e.detail.element);
});

Package detail

readme