var fKeyCode = 70;

var isScrolledUp = function(el) {
    var elementTop = $(el).offset().top;
    var elementBottom = elementTop + $(el).outerHeight();
    var viewportTop = $(window).scrollTop();
    return elementBottom < viewportTop;
};

document.body.addEventListener('keydown', function (e) {
    if (e.keyCode == fKeyCode) {
        $("article.story").each(function(i, el) {
            if (isScrolledUp(el)) {
                $(el).remove();
            }
        });
    }
});