<script>
var c="red,green,yellow,black,"
c+=c;
c+=c;
c+=c;
c=c.split(",");
document.body.bgColor=c[(new Date).getDate()-1];
</script>
另外一种切换背景颜色或图片：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>网页背景颜色自动切换</title>
</head>
<body bgColor="#ffffff" onload="chgCol(); pingpong();">
<script language="JavaScript">
<!-- Hide from JavaScript-Impaired Browsers
var pos = 10;
function initArray() {
this.length = initArray.arguments.length;
for (var i = 0; i < this.length; i++) {
this[i] = initArray.arguments[i];
}
}
var col=new initArray("4b","5b","8b","8b");
col[0] = "yellow";
col[1] = "coral";
col[2] = "orange";
col[3] = "red";
col[4] = "greenyellow";
col[5] = "lime";
col[6] = "turquoise";
col[7] = "coral";
col[8] = "blueviolet";
col[9] = "violet";
function chgCol() {
pos++;
if (pos<0||pos>9) {
pos = 0;
}
document.bgColor = col[pos];
setTimeout("chgCol()",5000);
}
var yourwords = "不斷變化背景色彩";var buffer1=" ";var buffer2=" ";var message1=buffer1+yourwords+buffer2;var dir = "left";var speed =150;function pingpong(){if (dir == "left") { message2=message1.substring(2,message1.length)+" "; window.status=message2;
setTimeout("pingpong();",speed); message1=message2; if (message1.substring(0,1) == "*") dir="right"; }else { message2=" "+message1.substring(0,message1.length-2); window.status=message2; setTimeout("pingpong();",speed); message1=message2;
if (message1.substring(message1.length-1,message1.length) == "*") dir="left"; }}// --></script>
<p align="center"> </p>
<p align="center"><b> 提示你：请等待几秒钟就可看到背景颜色的变化</b></p>
</body>
</html>