div 块跟随 鼠标点击

js：

$(document).ready(function () {

$(".company-contact ul li").click(function (ev) {
            var oTopic = document.getElementById('topic');
            var nScrollTop = document.documentElement.scrollTop || document.body.scrollTop;
            var nScrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;
            var oEvent = ev || event;
            oTopic.style.left = oEvent.clientX + 10 + nScrollLeft + 'px';
            oTopic.style.top = oEvent.clientY + 10 + nScrollTop + 'px';

});        });

html：

<div id="topic" style="display: block; position:absolute; top:505px; left:30px; width:96px; height:40px; border:1px red solid;">跟我走</div>