document.write("<div id='ad' style='height:80px;left:80px;position:absolute;top:80px;width:80px'><a href='广告链接地址' target='_blank'><img src='广告图片地址' border='0'></a></div>");
var xPos = 20;
var yPos = 20;
var step = 1;
var height = 0;
var Hoffset = 0;
var Woffset = 0;
var yon = 0;
var xon = 0;
var interval;
function mymove()
{
var width = document.documentElement.clientWidth;
var height = document.documentElement.clientHeight;
var scrollTop = document.documentElement.scrollTop;
var scrollLeft = document.documentElement.scrollLeft;
var Hoffset = ad.offsetHeight;
var Woffset = ad.offsetWidth;
ad.style.left = xPos + scrollLeft;
ad.style.top = yPos + 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);
}
interval = setTimeout("mymove();",30)
}
mymove();