A change of context is one of four things, and only four. The user agent changes, the viewport changes, focus moves, or the content changes in a way that changes the meaning of the page. Everything else your interface does when somebody clicks is a change of content, which is a different thing under different rules, and most of a modern interface lives there. No entry in WCAG's glossary carries more of the standard than this one. Three success criteria name it and either forbid it outright or make you warn about it first, and a fourth is scoped by it from the other side, because a status message is defined as a change in content that is not a change of context. The member people trip over is focus, since moving focus feels like a courtesy rather than an interruption and the definition counts it on its own terms. That is why a confirmation which announces itself and also takes focus gets read out twice.
In practice
Start by asking whether what your page just did is on the list at all, because that question closes most findings before the argument starts. An accordion opening, a menu unfolding, a tab panel swapping its contents, a filter narrowing a list in place. The standard names the first three itself as changes of content that do not change context, and both On Focus and On Input carry a standing note saying they are automatically met on a page where nothing does one of the four things. So a great deal of what looks like risk is already passing.
Then test the two triggers separately, because the two rules that use the term behave differently. Tab across every control and press nothing else, watching for anything that navigates, submits, opens a window or throws focus somewhere you did not send it. Then change every setting without activating anything, ticking each box and picking each option and leaving it alone. On Focus forbids a context change on arrival and offers no way out at all. On Input allows one, but only where the reader was told before they used the control, which means next to it rather than in a footer.
The fourth member is the one that reaches modern applications, and it does so through a parenthesis. The definition's example covers going to a new page and then adds anything that would look to a user as if they had moved to a new page. A client-side route change is designed to feel like exactly that, so the criterion applies even though no document was requested and no load event fired.
Why it matters
Two habits come out of this definition and they save real money. The first is that most dynamic behaviour on your site is allowed, so a report calling every panel swap a failure is reading the rule wrong and you can say so with the definition in hand. The second is the announce-or-move rule for feedback. Moving focus to a message is itself a change of context, which takes the message out of the status-message rule entirely, so putting a live region on it as well produces a double announcement rather than a safety net. Pick one route per message. There is no automated test rule for On Focus, On Input or Status Messages, so a clean scan proves only that nobody looked.
The confirmation that says everything twice
A form saves, a green banner appears carrying an alert role, and the page moves focus to it so nobody misses it. Both mechanisms fire. The live region announces the banner, then the screen reader reads whatever just took focus, which is the banner. The reader hears the same sentence back to back. Drop one. Either announce it and leave focus where it was, or move focus and take the live region off.
Where this shows up on the site
Related terms
- Status messageA status message is a change in content that tells you how something went, without moving focus to it.
- Live regionA live region is a part of the page marked so that assistive technology announces changes to it without the user having to go and look.
- Modal dialogA modal dialog is a window that opens over the page and blocks everything behind it until it closes.
- alertdialogAn alertdialog is a dialog that interrupts, and it is the role for a message somebody has to answer before anything else happens.
Knowing the word is the easy part.
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