Accessibility
Every experiment is built to a fixed set of accessibility requirements for the elements it adds to or changes on your page. This page lists those requirements, what is checked before an experiment is delivered, and where the requirements stop.
What every experiment does
| Requirement | Applies to |
|---|---|
| ARIA attributes are added | Every element the experiment creates |
| Keyboard access is kept | Every interactive element the experiment adds or changes |
| Focus is managed | Every point where the experiment adds or removes elements |
| Colour contrast meets WCAG AA | Text the experiment renders |
| Touch targets are at least 44 by 44 pixels | Interactive elements on touch devices |
| Changes are announced with live regions | Content the experiment updates while the page is open |
| Copy is supplied in every language the site supports | Every string the experiment shows, screen reader labels included |
The sections below say what each requirement means in practice.
Screen readers
- ARIA attributes on created elements. Any element the experiment creates carries the ARIA attributes appropriate to what it is, so a screen reader can name it and describe its role and state.
- Live regions for dynamic updates. Where the experiment changes content while the page is open, the change is placed in an
aria-liveregion so it is announced rather than silently swapped.
Keyboard and focus
- Keyboard access. Every interactive element the experiment adds or changes remains reachable and usable by keyboard alone.
- Focus management. When the experiment adds or removes elements, keyboard focus is moved deliberately, so a visitor is not left focused on an element that has gone or unable to reach one that has appeared.
Contrast and touch targets
- Colour contrast. Text the experiment renders meets the WCAG AA contrast ratios: 4.5:1 for normal text and 3:1 for large text.
- Touch targets. Interactive elements the experiment adds are at least 44 by 44 pixels on touch devices.
Language
Every string the experiment shows, including screen reader labels such as aria-label values, is supplied in each language your site supports and rendered in the language of the page the visitor is on. The root element the experiment injects declares its language with a lang attribute, so assistive technology reads the added content in the right language.
Checked before delivery
Before an experiment is delivered, it is checked against a list that covers:
- Keyboard navigation works
- Colour contrast meets WCAG AA
- ARIA attributes are appropriate
- Touch targets are an adequate size
What this covers
The requirements and the checks on this page apply to what the experiment itself adds to or changes on your page. They do not assess the accessibility of the rest of your site, and they are not an audit of your site against WCAG or any other standard.