BuddyPress.org

This function of a plugin

function wpjj_run_script() {
$post_id = get_the_id();
$file_url = get_post_meta($post_id, ‘custom_file’, true );
$site_parameters = array(
‘file_url’ => $file_url,
‘plugin_url’ => plugins_url(),
‘theme_directory’ => get_template_directory_uri(),
‘post_id’ => $post_id,
);
wp_localize_script( ‘customjs’, ‘wpjj_var’, $site_parameters );
}
add_action( ‘wp_footer’ , ‘wpvr_run_script’ );

add_action( ‘comment_form_logged_in_after’, ‘additional_fields’ );
add_action( ‘comment_form_after_fields’, ‘additional_fields’ );

Customize the wordpress default comment system
what can i do to run the same function so it can replace buddypress default comment system

I am a newbie in php
Thanks in advance