Interchange

Use with Images

Bandwidth is precious on mobile networks, so it helps to serve users on smaller screens a smaller image. Using Interchange, you can serve up specific images for users depending on their screen size. CSS media queries are used to determine what size the user's device is, and which image should be served.

In the below example, we have three different sizes of image: one for small screens, one for medium, and one for large. Use the below format to set up a responsive image. The image will change automatically as the browser resizes.

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<img data-interchange="[assets/img/interchange/small.jpg, small], [assets/img/interchange/medium.jpg, medium], [assets/img/interchange/large.jpg, large]">

The image set is a comma-separated list of items with this format:

[image_path, media_query]

image_path can be a relative or absolute path. media_query can be any CSS media query, or a Foundation breakpoint—see Named Media Queries below.

Use with HTML

Interchange can also swap in and out entire chunks of HTML. This allows you to load in mobile-friendly components on small screens, or more advanced versions on large screens.

In the below example, we've applied data-interchange to a <div> instead of an <img> element, and the paths are to HTML files instead of images.

<div data-interchange="[assets/partials/interchange-default.html, small], [assets/partials/interchange-medium.html, medium], [assets/partials/interchange-large.html, large]"></div>

Use with Background Images

When using Interchange on a non-<img> element, you can pass in an image path instead of an HTML path, and the element's background-image property will be set to the path of the matching rule.

<div data-interchange="[assets/img/interchange/small.jpg, small], [assets/img/interchange/medium.jpg, medium], [assets/img/interchange/large.jpg, large]"></div>

Named Media Queries

Interchange supports named queries as shorthands for full CSS media queries. Any breakpoint defined in the $breakpoints variable in your Sass will work, along with a few other keywords. Learn more about changing the default breakpoints.

To add your own named media queries, add them as properties to Foundation.Interchange.SPECIAL_QUERIES.

Foundation.Interchange.SPECIAL_QUERIES['square'] = 'screen and (aspect-ratio: 1/1)';

Programmatic Use

When using Interchange programmatically, you need to pass in your ruleset in the options object, as well as the container element, not the content elements, like so:

var $photoFrame = $('#some-container');
var interchange = new Foundation.Interchange($photoFrame, {
  rules: [
    "[path/to/default.jpg, small]", 
    "[path/to/medium.jpg, medium]",
    "[path/to/large.jpg, large]"
  ]
 });

var elem = new Foundation.Interchange(element, options);

$('#element').foundation('replace', path);

$('#element').foundation('destroy');