(function($) {
    $.fn.jMarquee = function(o) {
        o = $.extend({
            speed: 30,
            step: 1, //滚动步长
            direction: "up", //滚动方向
            visible: 1//可见元素数量
        }, o || {});
        //获取滚动内容内各元素相关信息
        var i = 0;
        var div = $(this);
        var ul = $("ul", div);
        var tli = $("li", ul);
        var liSize = tli.size();
        if (o.direction == "left")
            tli.css("float", "left");
        var liWidth = tli.innerWidth();
        var liHeight = tli.height();
        var ulHeight = liHeight * liSize;
        var ulWidth = liWidth * liSize;

        //如果对象元素个数大于指定的显示元素则进行滚动，否则不滚动。
        if (liSize > o.visible) {
            ul.append(tli.slice(0, o.visible).clone())  //复制前o.visible个li，并添加到ul的最后
            li = $("li", ul);
            liSize = li.size();

            //给滚动内容添加相关CSS样式
            div.css({ "position": "relative", overflow: "hidden" });
            ul.css({ "position": "relative", margin: "0", padding: "0", "list-style": "none" });
            li.css({ margin: "0", padding: "0", "position": "relative" });

            switch (o.direction) {
                case "left":
                    div.css("width", (liWidth * o.visible) + "px");
                    ul.css("width", (liWidth * liSize) + "px");
                    li.css("float", "left");
                    break;
                case "up":
                    div.css({ "height": (liHeight * o.visible) + "px" });
                    ul.css("height", (liHeight * liSize) + "px");
                    break;
            }


            var MyMar = setInterval(ylMarquee, o.speed);
            ul.hover(
            function() { clearInterval(MyMar); },
            function() { MyMar = setInterval(ylMarquee, o.speed); }
        );
        };
        function ylMarquee() {

            if (o.direction == "left") {
                if (div.scrollLeft() >= ulWidth) {
                    div.scrollLeft(0);
                }
                else {
                    var leftNum = div.scrollLeft();
                    leftNum += parseInt(o.step);
                    div.scrollLeft(leftNum)
                }
            }

            if (o.direction == "up") {
                if (div.scrollTop() >= ulHeight) {
                    div.scrollTop(0);

                }
                else {
                    var topNum = div.scrollTop();
                    topNum += parseInt(o.step);
                    div.scrollTop(topNum);
                }
            }

        };

    };

})(jQuery);