点击上下箭头，页码发生改变

还是看图，channel的length为总页数，向上取整，点击上下箭头，分别向上下滚动，拒绝疯狂点击多次加载事件，细节看代码

　　　　var clickLock = false;
            function calculateScrollTop (symbol) {
                var limit = 8;   //一页8个channel
                var itemHeight = 20;  //一个channel高20px
                var currentPage = $("#home_page").text() * 1; // home_page为当前页    注： *1是直接将text值转化为数字
                var allPages = Math.ceil(channelData.length / 8);  //向上取整 获取总页数
                var scrollTop = $('#line').scrollTop();  //获取滚动块的scrollTop值
                var flag = symbol ? currentPage < allPages : currentPage > 1;    // 根据传入参数判断点击的是上箭头还是下箭头   上箭头为0 下箭头为1
                if (flag) {
                    var changeTop = 0;
                    var size = (currentPage + (symbol ? 1 : -1)) * limit;
                    if (size > channelData.length) {
                        changeTop = (channelData.length - currentPage * limit) * itemHeight;
                    } else {
                        changeTop = limit * itemHeight;
                    }
                    if (changeTop != 0) {
                        clickLock = true;
                        $('#line').animate({"scrollTop": symbol ? scrollTop + changeTop: scrollTop - changeTop}, 200, 'linear', function () {clickLock = false});
                        $("#home_page").html($("#home_page").text() * 1 + (symbol ? 1: -1));
                    }
                }
            }
            $("#triangle-down").click(function(){//点击三角箭头向下滚动一页（8个通道）
                if (clickLock) return;
                calculateScrollTop(true);
            });
            $("#triangle-up").click(function(){//点击三角箭头向上滚动一页（8个通道）
                if (clickLock) return;
                calculateScrollTop(false);
            });