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.

Watch this part in video

<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]"
  ]
 });

JavaScript Reference

Initializing

The following files must be included in your JavaScript to use this plugin:

• foundation.core.js
• foundation.interchange.js
  • With utility library foundation.util.mediaQuery.js

Foundation.Interchange

Creates a new instance of Interchange.

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

Fires these events: Interchange#event:init

Name	Type	Description
element	Object	jQuery object to add the trigger to.
options	Object	Overrides to the default plugin settings.

---

Plugin Options

Use these options to customize an instance of Interchange. Plugin options can be set as individual data attributes, one combined data-options attribute, or as an object passed to the plugin's constructor. Learn more about how JavaScript plugins are initialized.

Name	Type	Default	Description
data-rules	array	null	Rules to be applied to Interchange elements. Set with the `data-interchange` array notation.
data-type	string	auto	Type of the responsive ressource to replace. It can take the following options: - `auto` (default): choose the type according to the element tag or the ressource extension, - `src`: replace the `[src]` attribute, recommended for images ``. - `background`: replace the `background-image` CSS property. - `html`: replace the element content.

---

---

Methods

replace

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

Update the src property of an image, or change the HTML of a container, to the specified path.

Fires these events: Interchange#event:replaced

Name	Type	Description
path	String	Path to the image or HTML partial.

---

_destroy

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

Destroys an instance of interchange.