= $number) { num = 0 } var leftdis = -2 * $w * num; $('.scroll ul').stop().animate({ left: leftdis }); }); //上一组 pre.click(function () { num--; if (num < 0) { num = $number - 1 } var rightdis = -2 * $w * num; $('.scroll ul').stop().animate({ left: rightdis }); }); });