HTML Checking for Large Sites

The <script> tag allows authors to include dynamic scripts and data blocks in their documents. When the src is present, this tag accepts a type attribute which must be either:

• an empty string
• text/javascript (that’s the default, so it can be omitted)
• module

Examples:

<!-- This is valid, without a type it defaults to JavaScript -->
<script src="app.js"></script>

<!-- This is valid, but will warn that it can be omitted -->
<script type="text/javascript" src="app.js"></script>

<!-- An empty attribute is valid, but will warn that it can be omitted -->
<script type="" src="app.js"></script>

<!-- The module keyword is also valid as a type -->
<script type="module" src="app.js"></script>

<!-- Any other type is invalid -->
<script type="wrong" src="app.js"></script>
<script type="text/html" src="app.js"></script>
<script type="image/jpeg" src="app.js"></script>

The autocomplete attribute is used to control if the browser can provide assistance in filling out form field values, and it only makes sense for visible, not hidden, inputs.

It is available on <input> elements that take a text or numeric value as input, <textarea> elements, <select> elements, and <form> elements.

To fix this issue, you can remove the autocomplete attribute from the input element with type=hidden. Here is an example:

<!-- Wrong code -->
<input type="hidden" name="phone" value="12345" autcomplete="off">

<!-- Correct code -->
<input type="hidden" name="phone" value="12345">

The aria-* attributes are part of the WAI-ARIA (Web Accessibility Initiative-Accessible Rich Internet Applications) suite. They are used to improve the accessibility of web pages. However, when we use an input element with a type attribute whose value is hidden, we imply that the element is invisible and has no interaction with the user. Therefore, it doesn’t make sense to add aria-* attributes to it.

To fix this issue, you need to remove the aria-* attributes from the input element with type=hidden. Here is an example:

<!-- Wrong code -->
<input type="hidden" name="referer" value="https://example.com" aria-invalid="false">

<!-- Correct code -->
<input type="hidden" name="referer" value="https://example.com">

When nesting an input element inside a label that has a for attribute, the id attribute of the input is required to match it.

The label element represents a caption in a user interface. The caption can be associated with a specific form control, known as the label element’s labeled control, either using the for attribute, or by putting the form control inside the label element itself.

When the input is inside the label, there’s no need to specify a for attribute as there can only be one input, as in this example:

<label>
  Age
  <input type="text" name="age">
</label>

However, if the for attribute is specified, then it must match the id of the input like this:

<label for="user_age">
  Age
  <input type="text" name="age" id="user_age">
</label>

The maxlength attribute can be used on an input element to define a client-side validation for the maximum length allowed on an input without resorting to JavaScript.

This attribute is only allowed on elements of type email, password, search, tel, text, or url.

The minlength attribute can be used on an input element to define a client-side validation for the maximum length allowed on an input without resorting to JavaScript.

This attribute is only allowed on elements of type email, password, search, tel, text, or url.

The minlength attribute defines the minimum number of characters (as UTF-16 code units) the user can enter into an <input> or <textarea>. This must be an integer value 0 or higher. If no minlength is specified, or an invalid value is specified, the input has no minimum length. This value must be less than or equal to the value of maxlength, otherwise the value will never be valid, as it is impossible to meet both criteria.

Here’s an example:

<label for="name">Enter your name (max 25 characters)</label>
<input type="text" minlength="25" id="name">

The pattern attribute is only allowed on input whose type is email, password, search, tel, text or url. Check the type used, and consider changing to one of the allowed types to enable pattern client-side validation.

The pattern attribute is a handy way of adding client-side validation on HTML forms without resorting to JavaScript. Check out this article to learn more about Input Pattern.

The <textarea> element does not have a type attribute.

The HTML <textarea> element represents a multi-line plain-text editing control, and is useful when you want to allow users to enter a sizeable amount of free-form text, for example a comment on a review or feedback form.

The step attribute is a number that specifies the granularity that the value must adhere to.

It sets the stepping interval when clicking up and down spinner buttons, moving a slider left and right on a range, and validating the different date types.

When used, it must be greater than zero.

Example:

<form>
  <!-- Valid values include 1.3, 3.3, 5.3, 7.3, 9.3, 11.3, and so on -->
  <input id="myNumber" name="myNumber" type="number" step="2" min="1.3" />
</form>

The max attribute on an <input> element does not accept an empty string.

The max attribute defines the maximum value that is acceptable and valid for the input containing the attribute.