scrollDetection

scrollDetection

$.fn.isOnScreen = function(shift) {
    if (!shift) {
        shift = 0;
    }
    var viewport = {};
    viewport.top = $(window).scrollTop();
    viewport.bottom = viewport.top + $(window).height();
    var bounds = {};
    bounds.top = this.offset().top + shift;
    bounds.bottom = bounds.top + this.outerHeight() - shift;
    return ((bounds.top <= viewport.bottom) && (bounds.bottom >= viewport.top));
};


var scrollDetection = function() {

    $('.js-scroll-detection').each(function() {
        var that = this;
        var shift = $(that).data('scroll-shift') || 20;

        if ($(that).isOnScreen(shift)) {
            $(that).addClass('js-isonscreen');
        }
    });

}