HTML Guide
The value company is not a valid option for the autocomplete attribute on an <input> element. You may use the organization value instead, as it can be used for “company name corresponding to the person, address, or contact information in the other fields associated with this field”.
The value contact is not a valid option for the autocomplete attribute on an <input> element.
The value Content-Script-Type is not valid for the property http-equiv on a meta tag.
The W3C HTML Validator issue you’re encountering indicates that the value specified for the http-equiv attribute in a <meta> tag is not valid. This often happens due to incorrect formatting, spelling errors, or extraneous characters in the attribute value.
To resolve this issue, ensure that the http-equiv attribute is spelled correctly and that it contains valid values. For a basic Content Security Policy (CSP), the correct way to specify it in the <meta> tag is as follows:
Correct Usage of <meta> with http-equiv
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="Content-Security-Policy" content="default-src 'self';">
<title>Document Example</title>
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>Fixes to Apply:
- Ensure Correct Spelling: The attribute value must be spelled exactly as “Content-Security-Policy” (case-sensitive).
- Check for Extraneous Characters: Make sure there are no extra quotes or spaces within the attribute value.
Example of a Bad Value:
If your original <meta> tag looks something like this:
<meta http-equiv=""Content-Security-Policy"" content="default-src 'self';">You should change it to:
<meta http-equiv="Content-Security-Policy" content="default-src 'self';">The value Content-Style-Type is not valid for the property http-equiv on a meta tag.
The type dob is not valid for an input. If you want to build a date picker field, you can use the native HTML input elements with type date, datetime-local, or a generic text input decorated with JavaScript and CSS.
In HTML, the type attribute for the <input> element specifies the type of input control that is to be displayed. The type attribute can have values like text, password, email, date, etc. Using an unsupported or invalid value like dob (which presumably stands for “date of birth”) will cause this validation error.
Here’s an example of how you can correct this issue by using a supported type attribute value for the date of birth input:
<label for="dob">Date of Birth:</label>
<input type="date" id="dob" name="dob">In this corrected example, we’ve used the type="date" attribute value for the date of birth input. This is a valid type for handling dates in HTML forms. Replace the input type with a supported type according to the specific data you need to capture.
Alternatively you can use a JavaScript library to build a date picker on a generic text input. For example, the popular bootstrap-datepicker library will generate a date picker around a text input.
All HTML elements may have the hidden boolean attribute set. When specified on an element, it indicates that the element is not yet, or is no longer, relevant, so browsers won’t render it.
Boolean attributes don’t accept values, its presence represents the true value and its absence represents the false value.
<!-- This is invalid because the hidden attribute should not have a value set -->
<div hidden="false"></div>
<!-- The correct way to hide a div is like this -->
<div hidden>This will be hidden</div>
<!-- And to show the element, we just don't hide it -->
<div>This won't be hidden</div>The action attribute on a <form> element is not a required attribute, but if specified, must be a valid, non-empty URL. For example:
<form action="register.php">
</form>The for attribute on a label element can’t be an empty string. This attribute is intended to specify which form element a label is associated with, and it must reference the ID of an existing form element. An empty string is neither a valid ID nor a meaningful association.
Explanation
- Invalid HTML: <label for=""></label>
The for attribute expects the value to be the ID of a form element, such as an input, textarea, select, etc.
How to Fix
- Identify the Form Element: Find the form element (input, textarea, select, etc.) that the label is supposed to be associated with.
- Assign an ID to the Form Element: Ensure the form element has a unique ID.
- Modify the Label’s for Attribute: Set the for attribute of the label to match the ID of the form element.
Example
Before Fix
<form>
<label for="">Username:</label>
<input type="text" name="username">
</form>After Fix
<form>
<label for="username">Username:</label>
<input type="text" id="username" name="username">
</form>An <a> element has been found with an invalid href attribute, containing more than one # adjacent character.
The # is used to separate the fragment part of an URI (typically used to indicate a section within a document). For example, this is a valid link to a URI containing a fragment:
<a href="https://example.com/faqs#pricing">pricing</a>The next example is invalid because it contains two adjacent # characters, so that the fragment part would be #pricing instead of pricing:
<a href="https://example.com/faqs##pricing">pricing</a>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.
The href attribute on the link element must not be empty.
The id attribute is used to identify a single element within a document, it’s not required, but if used it must be unique, and must not be an empty string.
IDs for HTML elements can’t be blank.
For rel="preload" and as="image" only, the imagesizes attribute is a sizes attribute that indicates to preload the appropriate resource used by an img element with corresponding values for its srcset and sizes attributes.
For rel="preload" and as="image" only, the imagesrcset attribute is a sourceset attribute that indicates to preload the appropriate resource used by an img element with corresponding values for its srcset and sizes attributes.
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 attribute rows on a textarea element, when present, must be a positive integer.
The <textarea> HTML element represents a multi-line plain-text editing control, 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. Its attributes rows and cols allow to define the dimensions of the text area by respectively specifying the numbers of rows and columns.
Example:
<textarea name="comments" rows="5" cols="25">
It all works great!
</textarea>An <iframe> element allows to embed an HTML document inside another HTML document, and its src attribute is indicated the source URL of the embedded web page. The src attribute is a required attribute, so it cannot be blank.
Example:
<iframe src="https://example.com/map.html"></iframe>The src attribute on an <img> element contains an invalid character, that should be properly encoded as a URI percent-encoded character.
The src attribute for <img> tags is required, to define the source of the image, like in this example:
<img src="photo.jpg" alt="wombat" />The sizes attribute is used to complement the srcset attribute on an <img> tag for responsive images. When this attribute is present, all image candidates must specify its width.
The tabindex attribute expects a valid integer value, not an empty string.
This attribute allows developers to make HTML elements focusable, allow or prevent them from being sequentially focusable (usually with the Tab key) and determine their relative ordering for sequential focus navigation.
This attribute accepts an integer value, where:
- A negative value means the element is not reachable via sequential keyboard navigation.
- A value of 0 means that the element should be focusable in sequential keyboard navigation, after any positive tabindex values. The focus navigation order of these elements is defined by their order in the document source.
- A positive value means the element should be focusable in sequential keyboard navigation, with its order defined by the value of the number. That is, tabindex="4" is focused before tabindex="5" and tabindex="0", but after tabindex="3".