HTML Checking for Large Sites
Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
An a
element with an href
attribute provides a link to a resource, so adding the link
role to it is redundant.
When not using semantic HTML for its intended purpose, interactive features must be re-implemented. For example, when role="link"
is added to an element, the tab
key should enable giving focus to the link and the enter
key should execute the link when focused.
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Related W3C validator issues
The <a> element requires either a href attribute, or a role attribute.
A button element, or an element with the role=button attribute, is not allowed to be nested inside an <a> element.
The href attribute of an <a> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
The href attribute on the link element must not be empty.
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The href attribute on an a tag expects a valid URL, but only http:// was found.
<a> tags can be used to link to an email address using the mailto protocol in the href attribute. Ensure that there is no space in the email address.
<a href="mailto: liza@example.com">This is wrong as it contains an space</a>
<a href="mailto:liza@example.com">This is OK</a>
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Space characters are not allowed in href attributes. Instead, they should be converted to %20. In this example, the first line is invalid and the second is valid:
<a href="https://example.com#some term">invalid</a>
<a href="https://example.com#some%20term">valid</a>
The href attribute on an <a> tag contains an space, which is not allowed. Consider replacing space characters with “%20”.
The href attribute on an element <link> contains a character that is not allowed, and should be encoded.
Some typical examples include the pipe character | that should be replaced by its encoded alternative %7C , and the left square bracket [ that needs to be encoded as %5B.
There can only be one visible <main> element in a document. If more are needed (for example for switching between them with JavaScript), only one can be visible, the others should be hidden toggling the hidden attribute.
Example of 2 main elements, where only one is visible:
<main>
<h1>Active main element</h1>
<!-- content -->
</main>
<main hidden>
<h1>Hidden main element</h1>
<!-- content -->
</main>
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