code: function(opts)
      {
          var i, arr = [];
          for (i = 0; i < 7; i++) {
              arr.push('<th scope="col"><abbr title="' + renderDayName(opts, i) + '">' + renderDayName(opts, i, true) + '</abbr></th>');
          }
          return '<thead>' + (opts.isRTL ? arr.reverse() : arr).join('') + '</thead>';
      }
docs: feature detection and helper functions