Código:
<!doctype html>
<html lang="es">
<head>
<meta charset="UTF-8">
<title>Cambiar fondo de p�gina con javascript • by Alfredo Gonz�lez P.</title>
<script type="text/javascript">
fondos = new Array();
fondos[0] = "images/1.jpg";
fondos[1] = "images/2.jpg";
fondos[2] = "images/3.jpg";
fondos[3] = "images/4.jpg";
fondos[4] = "images/5.jpg";
fondos[5] = "images/6.jpg";
fondos[6] = "images/7.jpg";
fondos[7] = "images/8.jpg";
fondos[8] = "images/9.jpg";
fondos[9] = "images/10.jpg";
fondos[10] = "images/11.jpg";
fondos[11] = "images/12.jpg";
fondos[12] = "images/13.jpg";
fondos[13] = "images/14.jpg";
fondos[14] = "images/15.jpg";
// tambi�n se puede crear un array as�
// var fondos = ["images/fondo.png","images/fondo1.png","images/fondo2.png"]
function fondoBody() {
var image = fondos[Math.floor(Math.random()*fondos.length)]
document.body.style.backgroundImage ="url("+image+")";
}
</script>
</head>
<body onLoad="javascript:fondoBody();">
</body>
</html>
