javascript - 为什么加载完所有项目后 CSS 加载器一直出现？

Question

我一直在使用CodeIgniter 3.1.8和 Twitter Bootstrap 4开发在线报纸/博客应用程序。

我目前正在通过 AJAX 加载更多帖子。

默认情况下，帖子分页并一次显示 12 个，在http://myblog.com/，http://myblog.com/?page=2，等等。

在 Posts 控制器 ( application\controllers\Posts.php) 我有

private function _initPagination($path, $totalRows, $query_string_segment = 'page')
{
    //load and configure pagination 
    $this->load->library('pagination');
    $config['base_url']             = base_url($path);
    $config['query_string_segment'] = $query_string_segment;
    $config['enable_query_strings'] = TRUE;
    $config['reuse_query_string']   = TRUE;
    $config['total_rows']           = $totalRows;
    $config['per_page']             = 12;

    if($this->Static_model->get_static_data()['has_pager']){
        $config['display_pages'] = FALSE;
        $config['first_link'] = FALSE;
        $config['last_link'] = FALSE;
        $config['prev_tag_open'] = '<li class="prev">';
        $config['prev_tag_close'] = '</li>';
        $config['next_tag_open'] = '<li class="next">';
        $config['next_tag_close'] = '</li>';
    }

    if (!isset($_GET[$config['query_string_segment']]) || $_GET[$config['query_string_segment']] < 1) {
        $_GET[$config['query_string_segment']] = 1;
    }
    $this->pagination->initialize($config);
    
    $limit  = $config['per_page'];
    $offset = ($this->input->get($config['query_string_segment']) - 1) * $limit;
    
    return array(
        'limit' => $limit,
        'offset' => $offset
    );
}

public function index()
{
    //call initialization method
    $config = $this->_initPagination("/", $this->Posts_model->get_num_rows());
    $data                  = $this->Static_model->get_static_data();
    $data['base_url']      = base_url("/");
    $data['pages']         = $this->Pages_model->get_pages();
    $data['categories']    = $this->Categories_model->get_categories();
    $data['search_errors'] = validation_errors();
    
    //use limit and offset returned by _initPaginator method
    $data['posts'] = $this->Posts_model->get_posts($config['limit'], $config['offset']);
    $this->twig->addGlobal('pagination', $this->pagination->create_links());
    
    // featured posts
    if ($data['is_featured']) {
        $data['featured'] = $this->Posts_model->featured_posts();
        $this->twig->addGlobal('featuredPosts', "themes/{$data['theme_directory']}/partials/hero.twig");
    }
    
    $this->twig->display("themes/{$data['theme_directory']}/layout", $data);
} 

为了改为通过 jQuery Ajax 加载帖子，我有：

(function($) {

    var currentPage = 1;

    $('.pagination').hide();

    $(window).scroll(function() {
        if ($(window).scrollTop() >= $(document).height() - $(window).height() - 10) {
            loadMore();
        }
    });

    function loadMore() {
        $.ajax({
                url: baseUrl + '?page=' + currentPage,
                type: 'GET',
                beforeSend: function() {
                    $('.loader').show();
                }
            })
            .done(function(data) {
                $('.loader').hide();
                // Get post from page 2 onward
                if (currentPage >= 2) {
                    var posts = $(data).find('#postsContainer').html();
                }
                // If there are no more posts, hide loader
                //  Otherwise, load more posts
                if (posts == 'undefined') {
                    $('.loader').hide();
                } else {
                    $('#postsContainer').append(posts);
                    currentPage = currentPage + 1;
                }
            });
    }

})(jQuery);

问题：

加载最后一篇文章后，如果我向上（或上下）滚动，加载器会反复显示和隐藏。

---

我究竟做错了什么？我该如何修复这个错误？

标签： javascriptphpjqueryajaxcodeigniter

Answer 1

我通过初始化变量并确保它不在显示加载程序之前解决posts了null这个posts问题undefined：

(function($) {

    var currentPage = 2,
        maxPage = $('#postsContainer').data('max-page'),
        posts = null;

    $('.pagination').hide();

    $(window).scroll(function() {
        var toBottom = $(window).scrollTop() >= $(document).height() - $(window).height() - 25;

        if (toBottom && currentPage <= maxPage) {
            loadMore();
        }
    });

    function loadMore() {
        $.ajax({
                url: baseUrl + '?page=' + currentPage,
                type: 'GET',
                beforeSend: function() {
                    if (typeof posts != 'undefined') {
                        $('.loader').show();
                    }
                }
            })
            .done(function(data) {
                $('.loader').hide();
                posts = $(data).find('#postsContainer').html();

                if (typeof posts != 'undefined') {
                    $('#postsContainer').append(posts);
                    currentPage = currentPage + 1;

                    if (currentPage > maxPage) {
                        $('#postsContainer').append('<p class="text-center text-muted">No more posts to load</p>');
                    }
                }
            });
    }

})(jQuery);

在控制器中：

public function index()
  {
    //call initialization method
    $config = $this->_initPagination("/", $this->Posts_model->get_num_rows());
    $data                  = $this->Static_model->get_static_data();
    $data['base_url']      = base_url("/");
    $data['pages']         = $this->Pages_model->get_pages();
    $data['categories']    = $this->Categories_model->get_categories();
    $data['search_errors'] = validation_errors();
    $data['posts'] = $this->Posts_model->get_posts($config['limit'], $config['offset']);
    $data['max_page'] = ceil($this->Posts_model->get_num_rows() / 12);

    $this->twig->addGlobal('pagination', $this->pagination->create_links());

    // Featured posts
    if ($data['is_featured']) {
      $data['featured'] = $this->Posts_model->featured_posts();
      $this->twig->addGlobal('featuredPosts', "themes/{$data['theme_directory']}/partials/hero.twig");
    }

    $this->twig->display("themes/{$data['theme_directory']}/layout", $data);
  }

在视图中：

<div id="postsContainer" data-max-page="{{max_page}}">