SIA-R9Refreshes implemented using the `<meta>` element have no delay

Accessibility requirements

This rule tests conformance of the following accessibility requirements:

Description

This rule checks that refreshes and redirects implemented using the <meta> element are not delayed.

Applicability

This rule applies to the first <meta> element of each document, where the element has an http-equiv attribute in the Refresh state and also has a content attribute with a value that is valid according to the specification of the attribute. As such, ignoring leading and trailing ASCII whitespace, the value must begin with a valid non-negative integer optionally followed a semicolon (;), one or more ASCII whitespace, and a valid URL that may be prefixed by the case-insensitive string URL=. The URL must not begin with either an apostrophe (') or a quotation mark (").

The specification of the http-equiv attribute describes in detail how to map the value of the attribute to its corresponding state.

Expectations

The time of the content attribute is either 0 or greater than 72000, corresponding to 20 hours.

The specification of the Refresh state describes in detail how to determine the time of the content attribute.

Assumptions

This rule makes the following assumption:

No functionality is provided for the user to adjust the time of the content attribute and that the redirect or refresh is not essential.

Accessibility support

This rule has no known accessibility support concerns.

Examples

Passed

In this document, the first <meta> element which has an http-equiv attribute in the Refresh state also has a valid content attribute whose time is 0 and therefore passes the rule:

<head>
    <meta http-equiv="refresh" content="0; http://example.com" />
    <meta http-equiv="refresh" content="5; http://example.com" />
</head>

This document is refreshed after more than 20 hours and therefore passes the rule:

<head>
    <meta http-equiv="refresh" content="72001" />
</head>

Failed

This document refreshes after 30 seconds and therefore fails the rule:

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

Inapplicable

In this document, the <meta> elements have either no http-equiv or no content attribute and are therefore inapplicable:

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

In this document, the content attributes are all invalid and are therefore inapplicable:

<head>
    <meta http-equiv="refresh" content="" />
    <meta http-equiv="refresh" content="; 30" />
    <meta http-equiv="refresh" content="+5; http://example.com" />
</head>

SIA-R9Refreshes implemented using the <meta> element have no delay