The Container ARIA Plugin makes it easy to use the WAI-ARIA Roles and States with the Container family of controls. Using the ARIA plugin, Dialogs, Alerts and Tooltips created using the Container family are more interoperable with assistive technologies (AT), such as screen readers, making them more accessible to users with disabilities.
Watch a screen cast of this example running in Firefox 3 with the NVDA screen reader, to see immediately the benefits that ARIA provides, or download the latest development snapshot of NVDA to test this example for yourself.
Using the Container ARIA Plugin is easy. Simply include the source file(s) for the ARIA plugin after the Container source files as indicated on the Container landing page.
All YUI ARIA Plugins require the user's browser and AT support the WAI-ARIA Roles and States.
Currently only Firefox 3 and
8 have support for ARIA, and are supported by several screen readers for
Windows that also offer support for ARIA. For this reason the YUI ARIA Plugins are only enabled
by default for these browsers. To enable the ARIA plugin for other browsers, simply the set
usearia configuration property to
true. For example:
Both the Module and Overlay widgets make use of iframes — Module for the purpose of
textResize Custom Event, and Overlay provides an iframe shim to
<select> from poking through Overlay instances. In both cases
the iframe elements are hidden from the user using CSS. To ensure these iframes also remain
hidden from AT, the Container ARIA Plugin sets the
role attribute of each iframe to
presentation and sets
tabIndex attribute to
All Container widgets inherit a
visible configuration property from Module. To
ensure that the visible state is properly conveyed to AT, the Container ARIA Plugin automatically
attribute to the correct value when the value of the
visible configuration property
The Container ARIA Plugin adds a
configuration properties to the Menu class, each of which maps back to their respective ARIA
The Container ARIA Plugin adds a
role configuration property to Panel that is set to
dialog by default. Authors using Panel (or any of its subclasses) to replace
role configuration property to
alertdialog. As an additonal convenience, the Container ARIA Plugin automatically
sets the value of the
labelledby configuration property to a Panel's header element.
The Container ARIA Plugin adds some keyboard enhancements to Panel:
Pressing the Esc key will automatically hide a Panel instance, or in the case of Dialog, call
cancel method. Each Panel is also automatically registered with an OverlayManager
instance, and listens for the DOM focus and blur events so that Panels are automatically focused
and blurred accordingly by the OverlayManager. Lastly, when a Panel instance is hidden, focus
is automatically returned to the element in the DOM that was focused before the Panel was made
The Container ARIA Plugin enhances Tooltip such that each DOM element defined as a Tooltip
instance's trigger has its
attribute automatically set to the Tooltip's id. Additionally, when a Tooltip is automatically
shown and hidden as it's trigger(s) are focused and blurred.
In keeping with the WAI-ARIA Best Practices for keyboard navigation the ARIA plugin for Menu enhances Menu's default behavior such that only one MenuItem is in the browser's tab index, enabling the user to easily tab into and out of the Menu. When a MenuItem in a Menu has focus, pressing the arrow keys moves focus between each MenuItem in the Menu.
Two of the leading screen readers for Windows, JAWS and Window-Eyes, support ARIA. Free, trial versions of both are available for download, but require Windows be restarted every 40 minutes. The open-source NVDA Screen Reader is the best option for developers as it is both free and provides excellent support for ARIA.
Note: Logging and debugging is currently turned off for this example.
All YUI 2.x users should review the YUI 2.8.2 security bulletin, which discusses a vulnerability present in YUI 2.4.0-2.8.1.