// 
function generateRandomHeaderImage(imagesInDirectory,altText,width) {
	randomNumber = Math.floor(Math.random() * imagesInDirectory + 1);
	
	headerImage = document.getElementById("header-image");
	headerImage.src = "images/image_" + randomNumber + ".jpg";
	if (altText != null)
		headerImage.alt = altText;
	if (width != null)
		headerImage.width = width;
}