HTML Checking for Large Sites
Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
Start tag “a” seen in “table”.
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>
Learn more:
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>
Learn more:
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.
Learn more:
Still checking your large sites one page at a time?
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.
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.
Learn more:
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>
Learn more:
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>
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 value used in the target property of an <a> element has been identified as a keyword because it starts with an underscore _, but it’s not a valid keyword.
Values starting with an underscore for the target property are used for reserved keywords like _blank, _self, _parent or _top.
Learn more:
The value provided on the type attribute of an a element is not a valid MIME type.
The type attribute expects a MIME type that hints at the linked URL’s format.
Read more:
50,000 Accessibility and HTML checks per month. Fully automated.
Let our automated scanner check your large sites using Axe Core and W3C Validator.
The type attribute on <a> elements, when present, gives a hint on the MIME type of the linked resource, for example:
<a href="application/pdf" src="book.pdf">Read our book</a>
<a href="image/jpeg" src="photo.jpeg">See a photo</a>
That is, we’re talking about the type of the linked resource, not the type of the <a> element, as it’s sometimes misunderstood. The following example is invalid because button is not a valid MIME type.
<a href="/order.php" type="button">Submit</a>
Learn more:
The <a> element requires either a href attribute, or a role attribute.
Learn more:
An </a> end tag has been found to violate nesting rules. <a> tags can’t include other <a> tags inside. Most probable cause is an unclosed <a> tag, like in this example:
<a href="one.html">Page 1
<a href="two.html">Page 2</a>
A table row tr has been found, containing no td cells. Check the table and remove empty rows.
Table contents is organized in rows using the <tr> element, which must contain cells using the <td> element, as in this example:
<table>
<thead>
<tr>
<th>Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
<td>Liza</td>
<td>12</td>
</tr>
<tr>
<td>Jimmy</td>
<td>14</td>
</tr>
</tbody>
</table>
A tr with no td cells on it will raise an issue, as in this example:
<table>
<thead>
<tr>
<th>Name</th>
<th>Age</th>
</tr>
</thead>
<tbody>
<tr>
</tr>
<tr>
<td>Jimmy</td>
<td>14</td>
</tr>
</tbody>
</table>
Note that self-closing <tr/> elements also count as empty rows as are like <tr></tr>.
An <a> tag can’t include other <a> tags inside. Most probable cause is an unclosed <a> tag, like in this example:
<a href="one.html">Page 1
<a href="two.html">Page 2</a>
A <table> contains an incoherent number of columns on one of its rows. Check the structure of the table to find the invalid row.
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 5 columns by means of a colspan attribute:
<table>
<!-- This first row sets the table as 2 columns wide -->
<tr>
<td>First</td>
<td>Second</td>
</tr>
<!-- This second row tries to use 5 columns -->
<tr>
<td colspan="5">Wrong</td>
</tr>
</table>
Learn more:
The <th> HTML element defines a cell as a header of a group of table cells, and must appear within a <tr> element.
In the following example for a simple table, the first <tr> contains two <th> header cells naming the values for each column:
<table>
<tr>
<th>Name</th>
<th>Age</th>
</tr>
<tr>
<td>Liza</td>
<td>49</td>
<tr>
<tr>
<td>Joe</td>
<td>47</td>
</tr>
</table>
Learn more:
A button element, or an element with the role=button attribute, is not allowed to be nested inside an <a> element.
A <label> tag can’t be used inside an <a> tag. Consider using other tags like <span>.
The <caption> element specifies the caption (or title) of a table. It’s not allowed for a <caption> to contain another table.
Links created with the <a> element no longer accept a shape attribute. In order to define image maps, use the <area> element instead.
Learn more:
Both <table> and <td> elements no longer accept a width attribute. Instead, you should use CSS as in this example:
<table style="width:100%;">
<tr>
<td style="width:50px;">Name</td>
</tr>
</table>
25,000 HTML checks per month. Fully automated.
Save time using our automated web checker. Let our crawler check your web pages on the W3C Validator.