随机漂浮

<script language="javascript" type="text/javascript">
            // JavaScript Document
            //设置广告块
            var divLeft = 0;
            //设置广告块初始左边位置
            var divTop = 0;
            //设置广告块初始顶部位置
            var divWidth = 142;
            //设置广告块宽度
            var divHeight = 52;
            //设置广告块高度
            var divImg = "http://img1.qq.com/pinglun/pics/7689/7689781.gif";
            //设置广告图片的URL地址
            var divUrl = "http://www.163.com";
            //设置广告链接
            var divTitle = "广告1";
            //设置div标题
            document.write("<DIV id=\"adDiv123\" style=\"position:absolute; left:"+divLeft);
            document.write("px; top:"+divTop+"px; width:"+divWidth+"px; height:"+divHeight);
            document.write("px; z-index:1;\" onMouseOver=\"javascript:window.clearInterval(varId)\"");
            document.write(" onMouseOut=\"javascript:beginMoveAd();\"><a href=\""+divUrl+"\" target=\"_blank\">");
            document.write("<img src=\""+divImg+"\" border=\"0\" alt=\""+divTitle+"\"></a><br>");
            document.write("<a href=\"javascript:\" onclick=\"document.getElementById('adDiv123').style.display='none';\">");
            document.write("<font color=\"#FFFFFF\">关闭广告</font></a>");
            document.write("</DIV>");
            //飘浮广告
            var _stepx=2;_stepy=2;
            //初始化每次偏离的象素
            var moveSpeed=40;
            //速度
            var varId;
            //获取setInterval的ID
            function moveAd()
            {
             //飘浮广告主函数
             var adLeft=parseInt(adDiv123.style.left);
             var adTop=parseInt(adDiv123.style.top);
             var adWidth=parseInt(adDiv123.style.width);
             var adHeight=parseInt(adDiv123.style.height);
             var _bodyLeft=document.body.scrollLeft;
             var _bodyTop=document.body.scrollTop;
             var _bodyHeight=document.body.clientHeight+_bodyTop;
             var _bodyWidth=document.body.clientWidth+_bodyLeft;
             if(adLeft<=_bodyLeft)
             {
              _stepx=2;
             }
             if(adTop<=_bodyTop)
             {
              _stepy=2;
             }
             if((adLeft+adWidth)>=_bodyWidth)
             {
              _stepx=-2;
             }
             if((adTop+adHeight)>=_bodyHeight)
             {
              _stepy=-2;
             }
             adDiv123.style.left=adLeft+_stepx;
             adDiv123.style.top=adTop+_stepy;
            }

            function beginMoveAd()
            {
             //启动飘浮
             varId = window.setInterval("moveAd()",moveSpeed);
            }
             //给窗体的load事件附加飘浮函数
            window.onload=beginMoveAd;
    </script>