var menu = document.getElementById("nav");
var menuLinks = menu.getElementsByTagName("a");
var currentUrl = location.href;

for(i=1; i<menuLinks.length; i++){
	var currentUrl = location.href;
	var linkHref = menuLinks[i].getAttribute("href");
	
	linkHref = linkHref.replace(/\.\.\//, "");
	linkHref = linkHref.replace(/index\.php/, "");

	if(currentUrl.match(linkHref)){
	  var lastMatch = i;
	}
}

var onState = document.createAttribute("class");
onState.nodeValue = "on";
menuLinks[lastMatch].attributes.setNamedItem(onState);