Change this into pagination to avoid reloading the page

Please help me how to change this into pagination or show more without reloading the page, I tried some solutions but not working, I'm stuck.

    if($query->found_posts > 6 && $limit == 6):
        $html .= "<div class='show_more document-search'><a href='?show=all' class='btn'>SHOW MORE</a></div>";
    endif;