Dynamic Content and Accessibility
- Is the event used to trigger a change device independent? If the mouse is required, then it is not fully accessible.
- Is the dynamic content or functionality itself accessible? If assistive technologies cannot adequately access dynamically triggered content or functionality, then it is not fully accessible.
document.write or other functions is generally accessible to assistive technologies. In some cases, however, if the dynamic content is constantly changing or if it changes while the user is reading it or has set focus to it, this can interfere with navigation or browser functionality and cause accessibility problems. For example, if an element that has keyboard focus is significantly changed, hidden, or removed from the page, keyboard focus may revert to the very beginning of the page.
focus()) after it appears to ensure it is navigated or read immediately. Additional techniques may be necessary to ensure accessibility for such dynamic elements - a modal dialog, for example, may need to be programmed to maintain keyboard focus (rather than allowing focus into other parts of the page that are not available).
As you can see, there are many difficulties in both usability and accessibility that arise through the use of pop-up windows. Care must be taken in making the decision to use them. If they are used, thorough user testing of your implementation is vital to ensure accessibility. It is generally best to alert the user to the fact that a pop-up window will be opened.
Redirecting and Refreshing Browser Windows
When the page the browser is viewing suddenly changes or refreshes, the person viewing that page may become disoriented or confused, especially if that person is using an assistive technology. This is commonly done with page redirects when page content has been moved or updated, or with scripting or
<meta> tags to refresh pages automatically. Accessibility guidelines requires that users be given control over time sensitive content changes. Do not automatically change or refresh the browser window without first alerting the user that the change will occur and giving him/her the ability to disable or postpone the change, or even better, give the user full control over the page change or redirect.
It's important to note that CSS is intended for visual styling. As such, screen readers largely ignore CSS. It should not generally be used to present content or functionality, at least not without ensuring the content or functionality is fully accessible. Using CSS alone to produce dynamic content should only employed with much testing in a variety of browsers and screen readers.