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Audit meta-refresh

Ensure <meta http-equiv="refresh"> is not used for delayed refresh

Impact:

Critical

WCAG-Konformität:

A
WCAG 2.2.1

Issue type:

failure

Meta element has no refresh delay

This rule checks that the `meta` element is not used for delayed redirecting or refreshing.

Applicability

This rule applies to the first meta element in a document for which all the following are true:

the element has an http-equiv attribute value of "refresh"; and
the element has a valid content attribute value, as described in the meta refresh pragma directive.

Expectation

For each target, the time from the content attribute value is either 0 or more than 72000 (20 hours). To determine the time, run the shared declarative refresh steps on the meta element as described in the HTML refresh state.

Background

The meta http-equiv="refresh" directive is an HTML tag used to instruct browsers to automatically refresh or reload a web page after a specified time interval. This can be useful for updating content dynamically or redirecting users to another page.

The content attribute in the meta http-equiv="refresh" directive is used to define the time interval, in seconds, after which the browser should automatically refresh or reload the web page. For example, content="5" would instruct the browser to refresh the page every 5 seconds. Careful consideration of the refresh interval is crucial to ensure optimal user experience and accessibility, particularly for individuals who may require more time to consume or interact with web content.

Because a refresh with a timing of 0 is a redirect, it is exempt from this rule. Since this can cause rapid screen flashes it is strongly recommended to avoid this.

Assumptions

This rule assumes no functionality was provided by the website for the user to adjust the timer.
This rule assumes that the refresh was not essential, which is listed as a valid exception to 2.2.1 Time Adjustable.

Accessibility Support

Not all major web browsers parse the value of the content attribute in the same way. Some major browsers, when they are unable to parse the value, default to a 0 seconds delay, whereas others will not redirect at all. This can cause some pages to be inapplicable for this rule, while still having a redirect in a minority of web browsers.

Bibliography

Test Cases

Passed

Passed Example 1

This page redirects to a new page immediately.

<head>
	<meta http-equiv="refresh" content="0; URL='https://github.com'" />
</head>

Passed Example 2

The first valid meta element on this page redirects to a new page immediately.

<head>
	<meta http-equiv="refresh" content="0; https://w3.org" />
	<meta http-equiv="refresh" content="5; https://w3.org" />
</head>

Passed Example 3

This page redirects after more than 20 hours.

<head>
	<meta http-equiv="refresh" content="72001; https://w3.org" />
</head>

Failed

Failed Example 1

This page refreshes after 30 seconds.

<head>
	<meta http-equiv="refresh" content="30" />
</head>
<body>
	<p>This page refreshes after 30 seconds.</p>
</body>

Failed Example 2

This page redirects to a new page after 30 seconds.

<head>
	<meta http-equiv="refresh" content="30; URL='https://w3.org'" />
</head>
<body>
	<p>This page redirects afte 30 seconds.</p>
</body>

Failed Example 3

The first meta element on this page is not valid because it uses colon (":") rather than semicolon (";"). The second meta element redirects to a new page after 5 seconds.

<head>
	<meta http-equiv="refresh" content="0: https://w3.org" />
	<meta http-equiv="refresh" content="5; https://w3.org" />
</head>
<body>
	<p>This page refreshes after 5 seconds.</p>
</body>

Failed Example 4

This page redirects to a new page after exactly 20 hours.

<head>
	<meta http-equiv="refresh" content="72000; https://w3.org" />
</head>
<body>
	<p>This page redirects after exactly 20 hours.</p>
</body>

Inapplicable

Inapplicable Example 1

This page will not refresh because it lacks a content attribute.

<head>
	<meta http-equiv="refresh" />
</head>
<body>
	<p>This page does not refresh.</p>
</body>