Automagic menu (Javascrip snippet)

var loc = document.location.toString();
var location_parts = loc.split('/');
this_loc = location_parts[location_parts.length-1];
if(this_loc == '' || this_loc == undefined) {
  $('#nav li a[href=\'index.php\']').addClass('selected');
}
else {
  $('#nav li a[href=\'' + this_loc + '\']').addClass('selected');
}