code: function (a, b) {
                          var result = 0,
                              sumA = sum(a),
                              sumB = sum(b);
                          if (!isNaN(sumA) && sumA !== 0 && !isNaN(sumB) && sumB !== 0) {
                              result = parseFloat(sumA) - parseFloat(sumB);
                          } else if (!isNaN(Date.parse(a[0])) && !isNaN(Date.parse(b[0]))) {
                              result = Date.parse(a[0]) - Date.parse(b[0]);
                          } else if (a[0] < b[0]) {
                              result = -1;
                          } else if (a[0] > b[0]) {
                              result = 1;
                          }
                          return result;
                      }
docs: Draw ascending by default