WCAG 2.0 Understanding Page

Intent

This Success Criteria is intended to help users of assistive technology be aware of changes that many users can easily see and understand.

There are a number of cases where content changes on a page after it is loaded. Users who are blind or have low vision that rely on a screen reader may have trouble knowing that information on a page changed. They may be working on the part of the page which is not near where changes have occurred on a page. It may be on a part of the web page that they have already read and wouldn't consider reviewing that part of the page for unannounced changes.

These messages would be very short in nature, such as:

"Your shopping cart has been updated, 5 items"
"Your form was successfully submitted."
"There are 5 results for your search"
"There are 3 errors on this form"
"Scores updated"
"content loading" (when a busy indicator is onscreen)

Examples of situations where this type of notification would be appropriate include:

Interactive controls may change the page based on a users selection
Filter / sort selections of data already displayed on page add/remove content
Additions and subtractions to/from a cart
A notification that 'support by chat' is available for this task at hand
Results of form submission when they are displayed on same page
A global error message placed above the form saying "form submission failed etc." or a thank you message after completion of a multi-step process
On switching from grid view to list view
In data table when sort column is changed
On selecting a different pagination link
When a graphical spinning "busy" signal notifies visual users

Dynamic changes to a page sometimes cause the page to become inactive for a period of time while it is being updated. Users of assistive technology may think the page has crashed and may loose their work if they either reload the page or leave the page thinking the browser crashed. This notification will ensure they are aware that something is happening in the background, the way that sighted users are aware when they see a spinning icon or the words "loading". If there is no such visual indication there is no requirement in the Success Criterion to provide programmatic notification, only when there is a visual notification, is there a requirement to make that notification also programmatic. This is not about the initial wait to load a new page. Those are announced to screen readers.

Note: SC 4.1.2 covers notification of changes in content that are a result of a change in the state of a control, such as selecting a new Tab in a tabbed interface, opening and closing a menu, clicking a link or button that opens up a dialog or tooltip. The text of 4.1.2 is "... states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies."

Benefits

Users of assistive technology will know what changed on the page, and will be able to make decisions based on that information.
Users who are blind will know if a shopping cart was successfully updated, or if form was successfully submitted, or if there were errors on their form.
Helps people with visual disabilities, cognitive limitations, and motor impairments by reducing the chance that a control will be accidentally activated or action will occur unexpectedly.
Individuals who are unable to detect changes on the page will be able to know what people who can see those changes know.

Techniques

This section references techniques that can be used to meet the Guideline or Success Criterion. There are sub-sections for sufficient techniques, advisory techniques, and failures.

Within each sub-section, there may be "situations" to describe when a set of techniques need to be considered. Remove the sub-section and heading if situations are not used.
Techniques are provided in an unordered list. Reference techniques by linking to the filename of the technique and using the technique ID as link text. Use unlinked plain text if the technique has not been written yet.
If more than one technique must be used for full sufficiency, list them in the same bullet separated by "AND".
If a general technique requires technology-specific techniques to be implemented, end the bullet with "using" and provide a sub-list of those techniques.
Square brackets indicate optional components.

Remove any parts of the template that are not used, such as the section and heading for situations, sub-lists of techniques, or the "AND" construction. Also remove the square brackets around placeholder optional components.

Sufficient

Techniques that are sufficient to meet the Guideline or Success Criterion.

Situation

ID [AND ID]* [using]
- ID

Advisory

Techniques that are not sufficient by themselves to meet the Guideline or Success Criterion.

Same template as sufficient techniques.

Failure

Techniques that document conditions that would cause the page not to meet the Guideline or Success Criterion, even if sufficient techniques are also used.

Same template as sufficient techniques.

Understanding Change in Content