WordPress Shortcode to add an iFrame dynamically

iframe-shortcode.php

<?php

function custom_html_render_shortcode_wp5431($attr)
{

    $id = (isset($attr['id']) && !empty($attr['id'])) ? sanitize_text_field($attr['id']) : null;
    $height = (isset($attr['h']) && !empty($attr['h'])) ? sanitize_text_field($attr['h']) : '160';
    $height .= (isset($attr['h_unit']) && !empty($attr['h_unit']) && $attr['h_unit'] == 'pixel') ? 'px' : '%';
    $width = (isset($attr['w']) && !empty($attr['w'])) ? sanitize_text_field($attr['w']) : '100';
    $width .= (isset($attr['w_unit']) && !empty($attr['w_unit']) && $attr['w_unit'] == 'pixel') ? 'px' : '%';

    $page = (isset($attr['page']) && !empty($attr['page'])) ? sanitize_text_field($attr['page']) : null;

    ob_start();

    if (!$id) :
        echo '<div class="url-missing">Please, Enter a valid ID</div>';
    else : ?>

        <iframe style="width:<?php echo esc_attr($width); ?>; height:<?php echo esc_attr($height); ?>;" src="https://<?php echo esc_attr($id) ?>.exprealty.com/<?php echo esc_attr($page); ?>" allowtransparency="true" frameBorder="0"> </iframe>

<?php endif;

    return ob_get_clean();
}
add_shortcode('exprealty-code', 'custom_html_render_shortcode_wp5431');