jQuery(document).ready(function($) {
    var $timeline_block = $('.cd-timeline-block');

    //hide timeline blocks which are outside the viewport
    $timeline_block.each(function() {
        if ($(this).offset().top > $(window).scrollTop()+$(window).height()*0.80) {
            $(this).find('.cd-timeline-img, .cd-timeline-content').addClass('is-hidden');
        }
    });

    //on scolling, show/animate timeline blocks when enter the viewport
    $(window).on('scroll', function() {
        $timeline_block.each(function() {
            if ($(this).offset().top <= $(window).scrollTop()+$(window).height()*0.80 && $(this).find('.cd-timeline-img').hasClass('is-hidden')) {
                $(this).find('.cd-timeline-img, .cd-timeline-content').removeClass('is-hidden').addClass('bounce-in');
            }
        });
    });
});
