This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung
Accessibility
Why should a page change only at the request of the visitor?
A selection field that changes the page immediately when you change it, a link that opens a new window without being asked, a page that redirects after five seconds: For people with audible reading or magnification, an unexpected change is a loss of orientation. Level A (3.2.1, 3.2.2) requires that focus and input do not trigger unexpected changes. Level AAA Criterion 3.2.5 requires that any change in context is only made upon explicit request or can be disabled.
What the Criterion Requires
A change of context is a change that takes the visitor to a different place: a new page, a new window, a change of focus to a different place, a fundamental rearrangement of the content. Such changes only happen if the visitor expressly triggers them, with a button, a link, a confirmation. A selection field that sends out when changing gets a button “Ads”. A link that opens a new window predicts that. A redirect by time becomes a redirect immediately (which the visitor does not notice) or a link. Alternatively, there is a setting that turns off such changes.
For whom this counts
He who works with a reading program hears only the place where he is; jumps the side, the thread is gone and the search for the connection takes minutes. Who greatly enlarges, sees a small section and often notices a change of sides only after a long search. Anyone who has a cognitive limitation loses the plan for what they just wanted to do with every unexpected change. Predictability is the basis for all three to work independently.
This is how we deal with it
The measurement finds selection fields with sends when changed, links with new window without indication and redirects with waiting time; This is automatically decidable. Whether there is an attitude to switch off or whether a change was announced, judges a person. The criterion belongs to the category AAA in knowledge.
Examples
Link opens a new window
<a href="/agb.pdf" target="_blank">AGB</a><a href="/agb.pdf" target="_blank">AGB (PDF, öffnet in neuem Fenster)</a>
<!-- oder ohne target: im selben Fenster -->Any change in context is only made upon explicit request or is announced; a submission infringes upon modification of a selection field.
- Replace each submission in the event of change (onchange) with a button that the visitor presses.
- Mark links that open a new window in the link text (“opens in new window”) or have them open in the same window.
- Replace redirects with waiting time by immediate redirects on the server or by a visible link.
- After an action, set the focus only where the visitor expects it: in the error message, in the window that he has opened.
