code: function compareAscending(a, b) {
        var ai = a.index,
            bi = b.index;
  
        a = a.criteria;
        b = b.criteria;
  
        // ensure a stable sort in V8 and other engines
        // http://code.google.com/p/v8/issues/detail?id=90
        if (a !== b) {
          if (a > b || typeof a == 'undefined') {
            return 1;
          }
          if (a < b || typeof b == 'undefined') {
            return -1;
          }
        }
        return ai < bi ? -1 : 1;
      }
docs: Used by `sortBy` to compare transformed `collection` values, stable sorting
  them in ascending order.
  
  @private
  @param {Object} a The object to compare to `b`.
  @param {Object} b The object to compare to `a`.
  @returns {Number} Returns the sort order indicator of `1` or `-1`.