Techniques for WCAG 2.0

Skip to Content (Press Enter)


F50: Failure of Success Criterion 2.2.2 due to a script that causes a blink effect without a mechanism to stop the blinking at 5 seconds or less


Technologies that support script-controlled blinking of content.

This failure relates to:


Scripts can be used to blink content by toggling the content's visibility on and off at regular intervals. It is a failure for the script not to include a mechanism to stop the blinking at 5 seconds or earlier. See SCR22: Using scripts to control blinking and stop it in five seconds or less (Scripting) for information about how to modify the technique to stop the blinking.


Failure Example 1

The following example uses script to blink content, but the blink continues indefinitely rather than stopping after five seconds.

<script type="text/javascript">
// blink "on" state
function show()
	if (document.getElementById)
	document.getElementById("blink1").style.visibility = "visible";
	settime-out("hide()", 450);
// blink "off" state
function hide()
	if (document.getElementById)
	document.getElementById("blink1").style.visibility = "hidden";
	settime-out("show()", 450);
// kick it off
<span id="blink1">This content will blink</span>



For each instance of blinking content:

  1. Determine if the blinking stops in 5 seconds or less.

Expected Results

If #1 is false, then the content fails the Success Criterion.