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Dynamic HTML 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 DHTML content or functionality itself accessible? If assistive technologies cannot adequately access DHTML triggered content or functionality, then it is not fully accessible.
Dynamic, constantly changing information is being written to the page in this example using the
The current time is displayed in the text box below. It updates and changes every second.
onclick="window.open(this.href); return false;">Select this...</a>
If you are using software to block pop-up windows, you may need disable the software or select the link in a way that bypasses the pop-up blocker (typically Ctrl + click or Ctrl + Enter with the link selected).
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. Always 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. Section 508 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.
Also, screen readers do not have great CSS
support, especially when presented with content that can be made visible
or invisible using either the
visibility:hidden styles. Many screen readers
do not read content that is assigned these styles even though the content
is still part of the underlying structure of the page. Until there is better
CSS support in both web
browsers and assistive technologies, using CSS
alone to produce dynamic content should only employed with much testing
in a variety of browsers and screen readers.