var applySeparator = function(listClass, maxPosts) {
    if(typeof listClass !== 'string' || typeof maxPosts !== 'number') {
        return;
    }

    var currentList;
    var lastPost;
    var allLists  = jQuery(listClass);
    var separator = jQuery('<div/>', {
        'class' : 'separator',
        css : {
            'border-bottom' : '4px solid red',
            'display' : 'block'
        }
    });

    for (var i = allLists.length - 1; i >= 0; i--) {
        console.log(currentList);
        currentList = jQuery(allLists[i]);
        currentList.find('.separator').remove();

        lastPost = currentList.find('.article').not('.list-item-depth-1').slice(0,maxPosts).last();

        if(lastPost.next().hasClass('list-item-depth-1')) {
            lastPost = lastPost.next();
        }

        lastPost.after(separator.clone());
    }
};

applySeparator('.article-list', 2);