code: function setComparator() {
      // If the first three letters are "asc", sort in ascending order
      // and remove the prefix.
      if (by.substring(0,3) == 'asc') {
        var i = by.substring(3);
        comp = function(a, b) { return a[i] - b[i]; };
      } else {
        // Otherwise sort in descending order.
        comp = function(a, b) { return b[by] - a[by]; };
      }
  
      // Reset link styles and format the selected sort option.
      $('a.sel').attr('href', '#').removeClass('sel');
      $('a.by' + by).removeAttr('href').addClass('sel');
    }
docs: Set comp, which is a comparator function used for sorting and
  inserting comments into the list.