sanitize_html_class() │ WP 2.8.0

Sanitizes an HTML classname to ensure it only contains valid characters.

Strips the string down to A-Z,a-z,0-9,_,-. If this results in an empty string then it will return the alternative value supplied.

1 time — 0.000024 sec (very fast) | 50000 times — 0.08 sec (speed of light) | PHP 7.1.2, WP 4.7.3
Hooks from the function

Return

String. The sanitized value

Usage

sanitize_html_class( $class, $fallback );
$class(string) (required)
The classname to be sanitized
$fallback(string)
The value to return if the sanitization ends up as an empty string.
Default: an empty string

Changelog

Since 2.8.0 Introduced.

Code of sanitize_html_class() WP 6.0

wp-includes/formatting.php 
function sanitize_html_class( $class, $fallback = '' ) {
	// Strip out any %-encoded octets.
	$sanitized = preg_replace( '|%[a-fA-F0-9][a-fA-F0-9]|', '', $class );

	// Limit to A-Z, a-z, 0-9, '_', '-'.
	$sanitized = preg_replace( '/[^A-Za-z0-9_-]/', '', $sanitized );

	if ( '' === $sanitized && $fallback ) {
		return sanitize_html_class( $fallback );
	}
	/**
	 * Filters a sanitized HTML class string.
	 *
	 * @since 2.8.0
	 *
	 * @param string $sanitized The sanitized HTML class.
	 * @param string $class     HTML class before sanitization.
	 * @param string $fallback  The fallback string.
	 */
	return apply_filters( 'sanitize_html_class', $sanitized, $class, $fallback );
}

sanitize_

Sanitizing, Escaping