我想问一个问题：我有一个源代码，它只适用于新帖子，但不适用于编辑帖子。那么，如果帖子标题存在，如何禁用编辑帖子上的发布按钮呢？

add_action(\'wp_ajax_check-posts-by-title\', function(){
    $title = isset( $_REQUEST[\'title\'] ) ? esc_attr( $_REQUEST[\'title\'] ) : null;
    // check for title
    if ( !$title ) {
        return wp_send_json(array(
            \'enable_btn\' => false,
            \'message\' => \'No title specified!\' 
        ));
    }
    $post = get_page_by_title($title, OBJECT, \'post\');
    // check for post
    if ( isset($post->ID) && \'publish\' === $post->post_status ) {
        return wp_send_json(array(
            \'enable_btn\' => false
        ));
    }
    // nothing caught
    return wp_send_json(array(
        \'enable_btn\' => true
    ));
    // kill response
    wp_die();
});

add_action(\'admin_footer\', function() { 
    global $pagenow;

    if ( !$pagenow || !in_array($pagenow, array( \'post-new.php\' )) )
        return; // only enqueue when writing/editing posts
    ?>
    <script>
        jQuery(document).ready(function($){
            $(document).on("change", "#titlediv #title", function(e){
                var i = $(this)
                  , f = i.closest(\'form\')
                  , t = i.val()
                  , b = $(\'input[name="publish"]\', f).first();

                if ( self.xhr ) {
                    self.xhr.abort();
                } else {
                    var xhr;
                }

                if ( !b.length ) return;
                b.attr(\'disabled\',\'disabled\');

                if ( $.trim( t ) ) {
                    self.xhr = $.ajax({type: \'post\', url: \'admin-ajax.php\', data: {
                        action: \'check-posts-by-title\',
                        title: t
                    }, success: function(res){
                        if ( res && res.enable_btn ) {
                            b.removeAttr(\'disabled\');
                        } else {
                            if ( res.message ) {
                                alert(res.message);
                            }
                        }
                    }, error: function(){
                        i.trigger(\'change\'); // roll over
                    }});
                }
            });
            $(\'#titlediv #title\').trigger(\'change\');
        });
    </script>
    <?php
});