Techniques for WCAG 2.0

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ARIA19: Using ARIA role=alert or Live Regions to Identify Errors

Applicability

Technologies that support Accessible Rich Internet Applications (WAI-ARIA).

This technique relates to:

User Agent and Assistive Technology Support Notes

See User Agent Support for WAI-ARIA for general information on user agent support.

Supports this technique:

Does NOT support this technique:

Support Notes:

When using Firefox with JAWS and NVDA role=alert is announced as "Alert" and aria-live=assertive does not include that extra text. There is NO support for NVDA 2013.1 + IE 8. The third example uses BOTH role=alert & aria-live=assertive on the error container for wider UA/AT support working in all combinations listed.

There are different methods to display an alert or assertive live region on the page and depending on how you create the error container or inject the error messages determines if it will work in the more difficult browsers/screen reader combinations like IE 8 + JAWS 14 or VoiceOver + Safari.

Description

The purpose of this technique is to notify Assistive Technologies (AT) when an input error occurs. The aria-live attribute makes it possible for an AT (such as a screen reader) to be notified when error messages are injected into a Live Region container. The content within the aria-live region is automatically read by the AT, without the AT having to focus on the place where the text is displayed.

There are also a number of special case live region roles which can be used instead of applying live region properties directly.

Examples

Example 1: Injecting error messages into a container with role=alert already present in the DOM

The following example uses role=alert which is equivalent to using aria-live=assertive.

In the example there is an empty error message container element with aria-atomic=true and an aria-live property or alert role present in the DOM on page load. The error container must be present in the DOM on page load for the error message to be spoken by most screen readers. aria-atomic=true is necessary to make Voiceover on iOS read the error messages after more than one invalid submission.

jQuery is used to test if the inputs are empty on submit and inject error messages into the live region containers if so. Each time a new submit is attempted the previous error messages are removed from the container and new error messages injected.

<script src="http://code.jquery.com/jquery.js"></script>
<script>
$(document).ready(function(e) {
	$('#signup').submit(function() {
		$('#errors').html('');
		if ($('#first').val() === '') {
			$('#errors').append('<p>Please enter your first name.</p>');
		}
		if ($('#last').val() === '') {
			$('#errors').append('<p>Please enter your last name.</p>');
		} 
		if ($('#email').val() === '') {
			$('#errors').append('<p>Please enter your email address.</p>');
		} 
		return false;
	});
});
</script>

<form name="signup" id="signup" method="post" action="">
  <p id="errors" role="alert" aria-atomic="true"></p>
  <p>
    <label for="first">First Name (required)</label><br>
    <input type="text" name="first" id="first">
  </p>
  <p>
    <label for="last">Last Name (required)</label><br>
    <input type="text" name="last" id="last">
  </p>
  <p>
    <label for="email">Email (required)</label><br>
    <input type="text" name="email" id="email">
  </p>
  <p>
    <input type="submit" name="button" id="button" value="Submit">
  </p>
</form>

A live example of the code can be used to demonstrate the differences in browser/AT support for this technology.

Resources

Resources are for information purposes only, no endorsement implied.

(none currently listed)

Tests

Procedure

  1. Determine that an empty error container role=alert or aria-live=assertive attribute is present in the DOM at page load.

  2. Trigger the error that causes the content in the live region to appear or update.

  3. Determine that the error message was injected into the already present error container.

Expected Results

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.

Techniques are Informative

Techniques are informative—that means they are not required. The basis for determining conformance to WCAG 2.0 is the success criteria from the WCAG 2.0 standard—not the techniques. For important information about techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.