Adding content before the loop in category pages

Question

I am creating a plugin and I want to show all sub category list in the top of every category page. I had created a function and call "wp_list_categories" in that function. The problem is when I call that via

add_filter('the_content', 'myfunction');

List of all sub category is return successfully. Before every post and i just want to show it in top before first post.

And when call same function via

add_filter('wp_list_categories', 'myfunction');

Nothing return and show blank page

Answer 1

loop_start should be a good option. loop_start executes before the loop displays the first post

EXAMPLE:

add_action( 'loop_start', function ( $q )
{
    if (    $q->is_main_query() // Do this only for the main query
         && $q->is_category() // Only target category pages
    ) {

        // Add your code here 

    }
});