Proposed Meta element has no refresh delay

Description

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.

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.

Background

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.

Bibliography

Accessibility Requirements Mapping

2.2.1 Timing Adjustable (Level A)
- Learn more about 2.2.1 Timing Adjustable
- Required for conformance to WCAG 2.0 and later on level A and higher.
- Outcome mapping:
  - Any failed outcomes: success criterion is not satisfied
  - All passed outcomes: success criterion needs further testing
  - An inapplicable outcome: success criterion needs further testing
G110: Using an instant client-side redirect
- Learn more about technique G110
- Not required for conformance to any W3C accessibility recommendation.
- Outcome mapping:
  - Any failed outcomes: technique is not satisfied
  - All passed outcomes: technique needs further testing
  - An inapplicable outcome: technique needs further testing
H76: Using meta refresh to create an instant client-side redirect
- Learn more about technique H76
- Not required for conformance to any W3C accessibility recommendation.
- Outcome mapping:
  - Any failed outcomes: technique is not satisfied
  - All passed outcomes: technique needs further testing
  - An inapplicable outcome: technique needs further testing

Secondary Requirements

This rule is related to the following accessibility requirements, but was not designed to test this requirements directly. These secondary requirements can either be stricter than the rule requires, or may be satisfied in ways not tested by the rule:

2.2.4 Interruptions (Level AAA): This success criterion is more strict than this rule. This is because the rule allows redirects longer than 20 hours. Some of the passed examples do not satisfy this success criterion.
3.2.5 Change on Request (Level AAA): This success criterion is more strict than this rule. This is because the rule allows redirects longer than 20 hours. Some of the passed examples do not satisfy this success criterion.

Input Aspects

The following aspects are required in using this rule.

DOM Tree

Test Cases

Passed

Passed Example 1

Open in a new tab

This page redirects to a new page immediately.

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

Passed Example 2

Open in a new tab

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

Open in a new tab

This page redirects after more than 20 hours.

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

Failed

Failed Example 1

Open in a new tab

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

Open in a new tab

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

Open in a new tab

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

Open in a new tab

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

Open in a new tab

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>

Inapplicable Example 2

Open in a new tab

This page will not refresh because it lacks a http-equiv attribute.

<head>
	<meta content="30" />
</head>
<body>
	<p>This page does not refresh.</p>
</body>