虹色変化　赤⇒紫
<SCRIPT Language = "JavaScript">
<!--

function niji(){
for (x=0;x<=255;x++){
document.bgColor = 16711680+(256*x);
}

for (x=0;x<=255;x++){
document.bgColor = 16776960-(65536*x);
}

for (x=0;x<=255;x++){
document.bgColor = 65280+(1*x);
}

for (x=0;x<=255;x++){
document.bgColor = 65535-(256*x);
}

for (x=0;x<=255;x++){
document.bgColor = 255+(65536*x);
}
}


//-->
</SCRIPT>

</head>
<body>
<Script Language="JavaScript">
<!--
niji();
//-->
</Script>