Untitled

<!DOCTYPE html>
<html>
<body>

<button onclick="setbackground()">Press button</button>

<script>

function setbackground()
{
window.setTimeout( "setbackground()", 15000);

var index = Math.round(Math.random() * 10);

var ColorValue = "FFFFFF";

if(index == 1)
ColorValue = "003366";
if(index == 2)
ColorValue = "660066";
if(index == 3)
ColorValue = "FF0000";
if(index == 4)
ColorValue = "FFFF66";
if(index == 5)
ColorValue = "99FF33";
if(index == 6)
ColorValue = "00CC00";
if(index == 7)
ColorValue = "666633";
if(index == 8)
ColorValue = "3D9999";
if(index == 9)
ColorValue = "143333";
if(index == 10)
ColorValue = "1A1A80";

document.getElementsByTagName("body")[0].style.backgroundColor = "#" + ColorValue;

}
</script>

</body>
</html>