HTML Guide
An <a> element has been found in an invalid place within a <table> element.
For example, the following code would cause this issue:
<table>
<tr>
<a href="#">link</a>
</tr>
</table>
Instead, the <a> element should be inside a <td> element, as a <tr> can’t hold content directly:
<table>
<tr>
<td>
<a href="#">link</a>
</td>
</tr>
</table>Related W3C validator issues
Table rows on the same <table> element must have the same number of columns, which comes determined by the first tr row.
For example, this table is wrong as the first row defines 2 columns, while the second row tries to use 4 columns:
<table>
<tr>
<td>Liza</td>
</tr>
<tr>
<td>Jimmy</td>
<td>14</td>
</tr>
</table>A <table> contains a <tr> row that has less <td> columns than the column count established by the first row. Check the table to ensure all rows have the same number of columns.
For example, in the following table, the first <tr> row defines that it’s 2 columns wide, but the second <tr> row tries to use only 1 column:
<table>
<!-- This first row sets the table as 2 columns wide -->
<tr>
<td>First</td>
<td>Second</td>
</tr>
<!-- This second row has only 1 column -->
<tr>
<td>Wrong</td>
</tr>
</table>A button element, or an element with the role=button attribute, is not allowed to be nested inside an <a> element.
An <a> element cannot contain a descendant element with the attribute tabindex.
The <table> element does not accept a height attribute. Use CSS instead.
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 of the a element contains an invalid backslash character, which is not permitted in URLs.
According to the WHATWG HTML living standard, the href attribute must contain a valid URL. URLs use forward slashes (/) for path separators, and backslashes are not allowed as they can cause browsers and validators to misinterpret the address. Backslashes often arise when file paths are copied from Windows environments.
Correct Usage:
- Always use forward slashes / in your URLs.
- Remove any backslashes from href values.
Example of incorrect usage:
<a href="images\picture.jpg">View Picture</a>Corrected example:
<a href="images/picture.jpg">View Picture</a>The target attribute on <a> elements can’t be blank.
This attribute defines the browsing context for links, that is, where should the linked documents be opened. This was used extensively on the now deprecated <frame> element, so you could give the name of the frame to open the document in, but is now more used to force links to open in a separate tab or window using target="_blank". Another option is using a name, so the new browsing context can be referred to on subsequent clicks on links with the same target.
For example, this will force the links to open on a new tab:
<a href="https://example.com" target="_blank">will open a blank tab</a>The href attribute on an a tag expects a valid URL, but only http(s):// 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>