infinite_article_scroll.js

/*
    Copyright (C) 2015  PencilBlue, LLC

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

$(document).ready(function()
{
    var self = this;
    self.loadingArticles = false;
    self.noMoreArticles = false;
    self.offset = null;
    self.limit = null;

    $(document).scroll(function()
    {
        if(self.loadingArticles || self.noMoreArticles)
        {
            return;
        }

        var documentHeight = $(document).height();
        var scrollPosition = $(document).scrollTop() + $(window).height();

        if(scrollPosition >= documentHeight - 200)
        {
            self.loadingArticles = true;
            var parameters = (self.offset) ? '?offset=' + self.offset + '&limit=' + self.limit : '?';
            if(typeof infiniteScrollSection !== 'undefined') {
                if(parameters.length) {
                    parameters += '&';
                }
                parameters += 'section=' + infiniteScrollSection;
            }
            else if(typeof infiniteScrollTopic !== 'undefined') {
                if(parameters.length) {
                    parameters += '&';
                }
                parameters += 'topic=' + inifiniteScrollTopic;
            }
            $.getJSON('/api/content/get_articles' + parameters, function(result)
            {
                if(!result)
                {
                    return;
                }
                else if(result.data.count === 0)
                {
                    self.noMoreArticles = true;
                    return;
                }

                self.loadingArticles = false;

                if(!self.offset)
                {
                    self.offset = result.data.count * 2;
                    self.limit  = result.data.count;
                }
                else
                {
                    self.offset += result.data.count;
                }

                $('#articles').append(result.data.articles);
            });
        }
    });
});