If you want to extend the WordPress Tag Cloud Widget with your own custom CSS class, you can easily use the wp_generate_tag_cloud_data
filter like so:
function extend_tag_cloud($tag_data) {
return array_map (
function ( $item )
{
$item['class'] .= ' your-custom-class';
return $item;
},
(array) $tag_data
);
}
add_filter( 'wp_generate_tag_cloud_data', 'extend_tag_cloud');
Code language: PHP (php)
Docs: