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The accept
attribute may be specified to provide browsers with a hint of what file types will be accepted on an <input>
element. It expects a comma-separated list of allowed file types. Refer to the list of media types to check the accepted tokens. In this example, the first line is invalid while the second is valid:
<input name='file' type='file' accept='doc, docx, pdf' />
<input name='file' type='file' accept='text/doc, text/docx, application/pdf' />
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Related W3C validator issues
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.
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The href attribute of an <a> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
An illegal character has been found for the “href” attribute on the “link” element.
To fix this issue, find the “link” element in question and make sure that the “href” attribute contains a valid URL without any illegal characters.
Here’s some example HTML code of a link element:
<!DOCTYPE html>
<html>
<head>
<title>My Webpage</title>
<link rel="stylesheet" href="styles/main.css">
</head>
<body>
<h1>Welcome to my webpage!</h1>
<p>Here is some content...</p>
</body>
</html>
In the above example, the link element has a valid href attribute value of styles/main.css. Make sure that your href attribute values don’t contain any illegal characters.
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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.
The name attribute is required for all input elements.
The src attribute on an <img> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
<input> elements can’t have a search role. Instead, try with <input type="search">.
<input> elements of type search are text fields designed for the user to enter search queries into. These are functionally identical to text inputs, but may be styled differently depending on the user agent.
The search role is a landmark. Landmarks can be used by assistive technology to quickly identify and navigate to large sections of the document. The search role is added to the container element that encompasses the items and objects that, as a whole, combine to create search functionality. When a <form> is a search form, use the search role on the form.
Example of a search form:
<form role="search">
<label for="search-input">Search this site</label>
<input type="search" id="search-input" name="search">
<input value="Submit" type="submit">
</form>
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