var totalImages = 8;
var bg = new Image();

function randomImage(img) {
	img.src = "/layout/background/" + Math.floor(Math.random()*totalImages+1) + ".jpg";
}

function bgError() {
	randomImage(bg);
}
function bgLoaded() {
	document.body.style.backgroundImage = "url("+bg.src+")";
	document.body.style.backgroundRepeat='repeat'; 
	document.body.style.backgroundAttachment='fixed'; 	
}

bg.onabort = function() {bgError()};
bg.onerror= function() {bgError()};
bg.onload = function() {bgLoaded()};
randomImage(bg);