get Scrolling Event.

<script src="JS/jquery-1.7.1.js" type="text/javascript"></script>

<script type="text/javascript">

    $(document).ready(function() {

        var ROOT = (function() {

            var html = document.documentElement;

            var htmlScrollTop = html.scrollTop++;

            var root = html.scrollTop == htmlScrollTop + 1 ? html : document.body;

            html.scrollTop = htmlScrollTop;

            return root;

        })();

        // may be recalculated on resize

        var limit = (document.body.scrollHeight - $(window).height()) * 0.85;

        var visible = false;

        var last = +new Date;

        var didScroll = false;

        $(window).scroll(function() {

            didScroll = true;

        })

        setInterval(function() {

            if (didScroll) {

                didScroll = false;

                if (visible && ROOT.scrollTop < limit) {

                    hideCredit();

                    visible = false;

                } else if (!visible && ROOT.scrollTop > limit) {

                    showCredit();

                    visible = true;

                }

            }

        }, 30);

        function hideCredit() {

            console.log('The hideCredit function has been called.');

            alert("hide");

        }

        function showCredit() {

            console.log('The showCredit function has been called.');

            alert("show");

        }

    });

</script>