Techniques for WCAG 2.0

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SCR31: Using script to change the background color or border of the element with focus

Applicability

HTML and XHTML, CSS, Script

This technique relates to:

User Agent and Assistive Technology Support Notes

This technique can be used on user agents that don't support the :focus pseudoclass but do support script, including Microsoft Internet Explorer.

Description

This purpose of this technique is to allow the author to use JavaScript to apply CSS, in order to make the focus indicator more visible than it would ordinarily be. When an element receives focus, the background color or border is changed to make it visually distinct. When the element loses focus, it returns to its normal styling. This technique can be used on any HTML user agent that supports Script and CSS, regardless of whether it supports the :focus pseudoclass.

Examples

Example 1

In this example, when the link receives focus, its background turns yellow. When it loses focus, the yellow is removed. Note that if the link had a background color to begin with, you would use that color rather than "" in the script.

Example Code:


...
<script>
 function toggleFocus(el)
 {
  el.style.backgroundColor =  el.style.backgroundColor=="yellow" ? "inherit" : "yellow";
 }
</script>

...

<a href="example.html" onfocus="toggleFocus(this)" onblur="toggleFocus(this)">focus me</a>
...

Tests

Procedure

  1. Tab to each element in the page

  2. Check that the focus indicator is visible

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.