Filters the headings array before output.

$headings is an array of items, where each item has the following offsets:

• id
• title
• depth
• url

add_filter('joli_toc_headings', 'filter_headings', 10, 2);

// Example how to capitalize all the headings
function filter_headings( $headings ){ 
    $headings = array_map(function($heading){
        //for H2 only
        if ($heading['depth'] == 2){
            //Capitalizes the first word only
            $heading['title'] = ucfirst(strtolower($heading['title']));
        }
        return $heading;
    }, $headings);

    return $headings;
}

add_filter('joli_toc_headings', 'edit_headings', 10, 2);

// Example how to add a custom link to a specific heading
function edit_headings( $headings ){ 
    $headings = array_map(function($heading){
        if ($heading['id'] == 'target-id'){
            //edit id
            $heading['url'] = 'https://customlink.com';
        }
        return $heading;
    }, $headings);
 
    return $headings;
}