WordPress: Output CSS classes

output-css-classes.php

/**
 * Outputs a list of sanitized CSS class names.
 *
 * @param  array|string $classes List of class names (array or string with
 *                               class names separated by spaces or commas).
 * @param  bool         $echo    Echo the list of class names (defaults to true).
 * @return void|array
 */
function output_css_classes( $classes, $echo = true ) {

	// Append everything into a string.
	$class_list = '';

	if ( is_string( $classes ) ) {
		$class_list = str_replace( ',', ' ', $classes );
	}

	// Account for any elements in the array that could have multiple classes
	// separated by spaces or commas.
	if ( is_array( $classes ) ) {
		foreach ( $classes as $class ) {
			$class_list .= str_replace( ',', ' ', $class ) . ' ';
		}
	}

	// Cleanup the class list.
	$class_list = explode( ' ', $class_list );
	$class_list = array_map( 'sanitize_html_class', $class_list );
	$class_list = array_map( 'trim', $class_list );
	$class_list = array_filter( $class_list );

	$classes = implode( ' ', $class_list );

	if ( $echo ) {
		echo $classes; // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
	}

	return $classes;
}