meta element has no refresh delay (no exception)

  • Rule Type:atomic
  • Rule Id: bisz58
  • Last modified: Feb 02, 2021
  • Accessibility Requirements Mapping:
    • 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 to 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 to 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:

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:

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 is 0.

Assumptions

  • This rule assumes that no functionality was provided by the website for the user to adjust the timer.

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

Test Cases

Passed

Passed Example 1

Open in a new tab

This meta element redirects the user immediately. Users won't notice the change in context.

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

Passed Example 2

Open in a new tab

The first valid meta element redirects immediately.

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

Failed

Failed Example 1

Open in a new tab

This meta element refreshes the page after 30 seconds.

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

Failed Example 2

Open in a new tab

This meta element redirects the user after 30 seconds.

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

Failed Example 3

Open in a new tab

The first meta element is not valid (because of the colon instead of a semi-colon in the content attribute), the 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

This meta element redirects the user after 20 hours.

<head>
	<meta http-equiv="refresh" content="72001; http://example.com" />
</head>

Inapplicable

Inapplicable Example 1

Open in a new tab

This meta element has no content attribute.

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

Inapplicable Example 2

Open in a new tab

This meta element has no http-equiv="refresh" attribute.

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

Inapplicable Example 3

Open in a new tab

This meta element has an invalid content attribute (because of the colon instead of a semi-colon), and is therefore inapplicable.

<head>
	<meta http-equiv="refresh" content="0: http://example.com" />
</head>

Inapplicable Example 4

Open in a new tab

This meta element has an invalid content attribute, and is therefore inapplicable.

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

Inapplicable Example 5

Open in a new tab

This meta element has an invalid content attribute, and is therefore inapplicable.

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

Inapplicable Example 6

Open in a new tab

This meta element has an invalid content attribute, and is therefore inapplicable.

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

Inapplicable Example 7

Open in a new tab

This meta element has an invalid content attribute, and is therefore inapplicable.

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

Inapplicable Example 8

Open in a new tab

This meta element has an invalid content attribute, and is 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.


Useful Links


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. This section will not be included in the rule when it is published on the W3C website.

No Implementations

Implementation reports are not provided for this rule.

Acknowledgments

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