Techniques for WCAG 2.0

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# 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

## Applicability

Technologies that support script-controlled blinking of content.

This failure relates to:

- Success Criterion 2.2.2 (Pause, Stop, Hide)
  - How to Meet 2.2.2 (Pause, Stop, Hide)
  - Understanding Success Criterion 2.2.2 (Pause, Stop, Hide)

## Description

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.

## Examples

### Failure Example 1

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

Example Code:

    ...
    <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
    show();
    //-->
    </script>
    ...
    <span id="blink1">This content will blink</span>

## Related Techniques

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

## Tests

### Procedure

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.

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