I want to search certain page IDs and if those pages have children search them as well. Nothing gets displayed though.

My code, search.php

if (have_posts()) : while (have_posts()) : the_post(); ?>
<?php
// determine parent of current page
if ($post->post_parent)
{
    $ancestors = get_post_ancestors($post->ID);
    $parent = $ancestors[count($ancestors) - 1];
}
else
{
    $parent = $post->ID;
}
$children = get_pages("title_li=&child_of=" . $parent . "&echo=0&sort_column=menu_order");
foreach ($children as $child):
    if (get_the_ID() == $child || get_the_ID() == $parent)
    { ?>
    <div class="col-xs-12 col-sm-4 item">
            <div class="ft-image">
        <a href="<?php echo the_permalink(); ?>" style="background-image: url(<?php echo get_the_post_thumbnail_url(); ?>)"></a>
<h3 class="post-title"><?php echo the_title(); ?></h3>
                </div>
            <div class="content">
            <div class="intro">
                <?php
        // strip tags to avoid breaking any html
        $string = strip_tags(get_the_excerpt());
        $count = 130;

        if (strlen($string) > $count)
        {

            // truncate string
            $stringCut = substr($string, 0, $count);

            // make sure it ends in a word so assassinate doesn't become ass...
            $string = substr($stringCut, 0, strrpos($stringCut, ' ')) . '...';
        }
        echo $string;
?>
            </div>
        <a href="<?php echo the_permalink(); ?>" class="cta-btn"><?php echo __('Learn More', 'TMP'); ?></a>
            </div>
            </div>

                 <?php
    }
endforeach;
endwhile;
endif;

Also is it possible to make it in ajax?