Using sanitize_html_class to sanitize HTML class names in WordPress

The WordPress sanitize_html_class function is used to sanitize a HTML class name by removing all special characters, spaces, and converting it to a valid class name. This can be useful when dynamically generating class names for HTML elements based on user input or other dynamic data, ensuring that the class names are safe and valid for use in HTML and CSS.

  • It helps prevent potential security vulnerabilities by removing any potentially harmful characters from the class name.
  • It ensures that the class name complies with HTML and CSS standards, preventing any rendering or styling issues.
  • It allows for consistent and predictable class names to be used throughout the codebase, improving maintainability and readability.

The sanitize_html_class function helps in creating safe, valid, and consistent HTML class names for use in WordPress themes and plugins.

Parameters Accepted by WordPress sanitize_html_class Function

  • $classname (string, required): The classname to be sanitized.
  • $fallback (string, optional, default value: ”): The value to return if the sanitization ends up as an empty string.

The sanitize_html_class function in WordPress accepts two parameters. The first parameter is $classname, which is a required string that represents the classname to be sanitized. The second parameter, $fallback, is an optional string with a default value of an empty string. It is used to specify the value to return if the sanitization process results in an empty string.

Value Returned by WordPress sanitize_html_class Function

The sanitize_html_class function returns a string, which represents the sanitized value of the input classname.


Example 1: Sanitizing a Simple Class Name

$class_name = 'my-custom_class1';
$safe_class_name = sanitize_html_class($class_name);

echo '<div class="' . $safe_class_name . '">Content</div>';

This example demonstrates sanitizing a basic class name. The sanitize_html_class() function ensures that the class name is safe to use by removing any invalid characters. The result is then used in a div’s class attribute.

Example 2: Sanitizing a Class Name with Special Characters

$class_name = 'special!@#$%^&*()class';
$safe_class_name = sanitize_html_class($class_name);

echo '<div class="' . $safe_class_name . '">Content</div>';

In this example, sanitize_html_class() is used to clean a class name that includes special characters. These characters are removed, ensuring the output is a valid CSS class name.

Example 3: Using a Fallback for Invalid Class Names

$class_name = '12345'; // Class names cannot start with a digit
$fallback = 'default-class';
$safe_class_name = sanitize_html_class($class_name, $fallback);

echo '<div class="' . $safe_class_name . '">Content</div>';

Here, sanitize_html_class() is given a class name that starts with a digit, which is not valid in CSS. By providing a fallback, we ensure that a valid class name (‘default-class’) is used if the original class name is entirely invalid.


In conclusion, the sanitize_html_class function is a valuable tool for ensuring that HTML class names are safe and secure. By using this function, developers can prevent potential security vulnerabilities and maintain the integrity of their code. It is important to incorporate this function into the development process to protect against potential attacks and maintain the overall security of the application. By implementing best practices such as using sanitize_html_class, developers can create a more secure and reliable application for users.

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