Techniques for WCAG 2.0

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SCR22: Using scripts to control blinking and stop it in three seconds or less


Technologies that support script-controlled blinking of content.

This technique relates to:


The objective of this technique is to control blinking with script so it can be set to stop in less than three seconds by the script. Script is used to start the blinking effect of content, control the toggle between visible and hidden states, and also stop the effect at three seconds or less. The setTimeout() function can be used to toggle blinking content between visible and hidden states, and stop when the number of iterations by the time between them adds up to nearly three seconds.


Example 1

This example uses JavaScript to control blinking of some (X)HTML content. JavaScript creates the blinking effect by changing the visibility status of the content. It controls the start of the effect and stops it within three seconds.

<div id="blink1" class="highlight">New item!</div>
<script type="text/javascript">
// blink "on" state
function show()
	if (document.getElementById)
	document.getElementById("blink1").style.visibility = "visible";
// blink "off" state
function hide()
	if (document.getElementById)
	document.getElementById("blink1").style.visibility = "hidden";
// toggle "on" and "off" states every 450 ms to achieve a blink effect
// end after 2700 ms (less than three seconds)
for(var i=900; i < 2700; i=i+900)



For each instance of blinking content:

  1. Start a timer for 3 seconds at the start of the blink effect.

  2. When the timer expires, determine if the blinking has stopped.

Expected Results