使图片永远在页面顶端的特效代码

<div id=dd style="Z-INDEX: 1; WIDTH: 100px; POSITION: absolute; HEIGHT: 132px"> <a href="http://www.vevb.com/"><img src="/img/200406301.jpg" width="236" height="236" border="0" alt="马到成功！"></a></div><scr<a href="http://ip.vevb.com/">ip</a>t language=<a href="http://www.vevb.com/article.asp?typeid=160">java</a>Script><!-- Begin//more <a href="http://www.vevb.com/article.asp?typeid=36">Javascript</a> from http://www.vevb.comvar xPos = 20; // 起始横向位置(从左算起，单位象素)var yPos = document.body.clientHeight; // 页面本身高度var step = 1; var delay = 30; // 速度，值越大速度越慢var height = 0;var Hoffset = 0;var Woffset = 0;var yon = 0;var xon = 0;var pause = true;var interval;dd.style.top = yPos;function changePos() {width = document.body.clientWidth; // 判断浏览器窗口的宽度height = document.body.clientHeight; // 判断浏览器窗口的高度Hoffset = dd.offsetHeight;Woffset = dd.offsetWidth;dd.style.left = xPos + document.body.scrollLeft;dd.style.top = yPos + document.body.scrollTop;if (yon) {yPos = yPos + step;}else {yPos = yPos - step;}if (yPos < 0) {yon = 1;yPos = 0;}if (yPos >= (height - Hoffset)) {yon = 0;yPos = (height - Hoffset);}if (xon) {xPos = xPos + step;}else {xPos = xPos - step;}if (xPos < 0) {xon = 1;xPos = 0;}if (xPos >= (width - Woffset)) {xon = 0;xPos = (width - Woffset); }}function start() {dd.visibility = "visible";interval = setInterval('changePos()', delay);}function pause_resume() {if(pause) {clearInterval(interval);pause = false;}else {interval = setInterval('changePos()',delay);pause = true;}}start();// End --></script>