function isActive(_ref, indexOnly, currentLocation, routes, params) {
	  var pathname = _ref.pathname;
	  var query = _ref.query;

	  if (currentLocation == null) return false;

	  // TODO: This is a bit ugly. It keeps around support for treating pathnames
	  // without preceding slashes as absolute paths, but possibly also works
	  // around the same quirks with basenames as in matchRoutes.
	  if (pathname.charAt(0) !== '/') {
	    pathname = '/' + pathname;
	  }

	  if (!pathIsActive(pathname, currentLocation.pathname)) {
	    // The path check is necessary and sufficient for indexOnly, but otherwise
	    // we still need to check the routes.
	    if (indexOnly || !routeIsActive(pathname, routes, params)) {
	      return false;
	    }
	  }

	  return queryIsActive(query, currentLocation.query);
	}
Returns true if a <Link> to the given pathname/query combination is
currently active.