WordPress with ajax

ajax-script.js

    /* Ajax Page Setup */
        $page = jQuery('.link a');
        $page.on('click', function (e) {
            e.preventDefault();
            var pageID = jQuery(this).attr('data-id');
            
            var ajaxdata = {
                action: 'load_pages',
                page_id: pageID
            };
            
            jQuery.post(dtb_ajaxurl, ajaxdata, function (res) {
                console.log(res);
            });
        });

function.php

<?php
/**
 * Load Pages Ajax Function
 */
function rtp_load_pages(){

    if( isset( $_POST['page_id'] ) ) {
        
        $page_id = $_POST['page_id'];

        $page = get_page( $page_id );
        $content = $page->post_content;
        echo apply_filters('the_content', $content);
    }
  
    die(1);
}

add_action('wp_ajax_load_pages', 'rtp_load_pages');
add_action('wp_ajax_nopriv_load_pages', 'rtp_load_pages');

header-script.php

        <script type="text/javascript">
            var dtb_ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
        </script>