whole_func_string: function resolveUrlAttribute ($node, attr) {
      var url = $node.attr(attr);
      if (url === undefined) return '';
      if (isAbsoluteUrl(url)) {
        return url;
      } else {
        return urlUtil.resolve(base, url);
      }
    }
func_code_string: function resolveUrlAttribute ($node, attr) {
      var url = $node.attr(attr);
      if (url === undefined) return '';
      if (isAbsoluteUrl(url)) {
        return url;
      } else {
        return urlUtil.resolve(base, url);
      }
    }
func_documentation_string: extracts, and normalizes a url attribute value of a node