每次刷新更换图片的代码

<script language="javascript">
today=new Date();
jran=today.getTime();
function rnd() {
ia=9301;
ic=49297;
im=233280;
jran = (jran*ia+ic) % im;
return jran/(im*1.0);
};
function rand(number) {
return Math.ceil(rnd()*number);
};
document.write("<center>");
for(i=1;i<=1;i++) {
myNum=(rand(3)); //改成你要随机显示的图片数；
if(myNum == 1) document.write("<a href='http://www.edu.cn'><img src='http://www.eol.cn/images/indexnew/0712_zzbm.jpg' border=0></a>"); //图片路径，可用http://
if(myNum == 2) document.write("<a href='http://www.eol.cn'><img src='http://www.eol.cn/images//indexnew/0609_2006tbzy1.jpg' border=0></a>");
if(myNum == 3) document.write("<a href='http://www.cernet.com'><img src='http://www.eol.cn/images/indexnew/xianfanyi.jpg' border=0></a>");
else {
document.write();
}
}; </script>