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 test target, running the shared declarative refresh steps, given the target’s document, the value of the target’s content attribute, and the target results in time being either 0 or greater than 72000 (20 hours).

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 SC 2.2.1.

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

This rule is designed specifically for 2.2.1 Timing Adjustable, which can be satisfied if the time limit is over 20 hours long. All pages that fail this because of a “refresh” meta element also do not satisfy 2.2.3 No Timing and 3.2.5 Change on Request. In order to adequately test the expectation, some of the passed examples do not satisfy 2.2.3 No Timing and 3.2.5 Change on Request.

Bibliography

• Understanding Success Criterion 2.2.1: Timing Adjustable
• Understanding Success Criterion 2.2.4: Interruptions
• Understanding Success Criterion 3.2.5: Change on Request
• G110: Using an instant client-side redirect
• H76: Using meta refresh to create an instant client-side redirect
• F40: Failure of Success Criterion 2.2.1 and 2.2.4 due to using meta redirect with a time limit
• F41: Failure of Success Criterion 2.2.1, 2.2.4, and 3.2.5 due to using meta refresh with a time-out

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
• 2.2.4 Interruptions (Level AAA)

  • Learn more about 2.2.4 Interruptions
  • Required for conformance to WCAG 2.0 and later on level AAA.
  • 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
• 3.2.5 Change on Request (Level AAA)

  • Learn more about 3.2.5 Change on Request
  • Required for conformance to WCAG 2.0 and later on level AAA.
  • 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

Input Aspects

The following aspects are required in using this rule.

• DOM Tree

Test Cases

Passed

Passed Example 1

Open in a new tab

Redirects immediately.

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

Passed Example 2

Open in a new tab

First valid <meta http-equiv="refresh"> redirects 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

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

Refreshes after 30 seconds.

<head>
	<meta http-equiv="refresh" content="30" />
</head>

Failed Example 2

Open in a new tab

Redirects after 30 seconds.

<head>
	<meta http-equiv="refresh" content="30; URL='https://w3.org'" />
</head>

Failed Example 3

Open in a new tab

First <meta http-equiv="refresh"> element is not valid, second one redirects after 5 seconds.

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

Failed Example 4

Open in a new tab

Redirects after exactly 20 hours.

<head>
	<meta http-equiv="refresh" content="72000; https://w3.org" />
</head>

Inapplicable

Inapplicable Example 1

Open in a new tab

No content attribute.

<head>
	<meta http-equiv="refresh" />
</head>

Inapplicable Example 2

Open in a new tab

No http-equiv="refresh" attribute.

<head>
	<meta content="30" />
</head>

Inapplicable Example 3

Open in a new tab

content attribute is invalid and therefore inapplicable.

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

Inapplicable Example 4

Open in a new tab

content attribute is invalid and therefore inapplicable.

<head>
	<meta http-equiv="refresh" content="-00.12 foo" />
</head>

Inapplicable Example 5

Open in a new tab

content attribute is invalid and therefore inapplicable.

<head>
	<meta http-equiv="refresh" content="; 30" />
</head>

Inapplicable Example 6

Open in a new tab

content attribute is invalid and therefore inapplicable.

<head>
	<meta http-equiv="refresh" content="" />
</head>

Inapplicable Example 7

Open in a new tab

content attribute is invalid and therefore inapplicable.

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

Inapplicable Example 8

Open in a new tab

content attribute is invalid and therefore inapplicable.

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

Glossary

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

• For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, “an input element with a type attribute value of Text” can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
• For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
• For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
• For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
• For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
• For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification and the HTML Accessibility API Mappings.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

• Inapplicable: No part of the test subject matches the applicability
• Passed: A test target meets all expectations
• Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such “interim” results can be expressed with the incomplete outcome.

Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date.

Changelog

This is the first version of this ACT rule.