In a recent project, I made use of the built in WordPress Tag Cloud widget. The default widget gives you only a few options, none of which I found quite useful.
The project relied on the ability to be able to browse entries by tags and as a visual cue, I wanted to style the currently active tag. Most active list items that WordPress generates are conveniently tagged with a class identifier such as `active` or `current`. Unfortunately the Tag Cloud omits this feature.
Extending `[wp_tag_cloud()](https://web.archive.org/web/20211027161553/http://codex.wordpress.org/Function_Reference/wp_tag_cloud)`, here is a snippet that can be added to your theme’s `functions.php` file to add the functionality.
```php
add_filter ( 'wp_tag_cloud', 'tag_cloud_active_class' );
function tag_cloud_active_class( $taglinks ) {
if ( is_tag() ) {
$term_id = get_query_var('tag_id');
$taxonomy = 'post_tag';
$args ='include=' . $term_id;
$terms = get_terms( $taxonomy, $args );
$active_tag = $terms[0]->slug;
}
$tags = explode('', $taglinks);
$regex = "#(.*tag-link[-])(.*)(' title.*)#e";
foreach( $tags as $tag ) {
if (strpos($tag,$active_tag)) {
$tagn[] = preg_replace($regex, "('$1$2 '.'active-tag'.'$3')", $tag );
} else {
$tagn[] = preg_replace($regex, "('$1$2$3')", $tag );
}
}
$taglinks = implode('', $tagn);
return $taglinks;
}
```