function selectRandomPhoto(id,styleProp,arObj){
	var randMulti = arObj.length;
	var randIndex = Math.round(Math.random() * (randMulti - 1));
	var styleVal = "url('"+ arObj[randIndex] +"')";
	setStyleProp(id,styleProp,styleVal);
}

function setStyleProp(id,styleprop,stylevalue){
	if(document.getElementById(id)){
		var elm = document.getElementById(id);
		elm.style[styleprop] = stylevalue;
	}
}