Comparable.js

// For use with MooTools
// Published under MIT license

window.Comparable = new Class({
  // You class needs to implement "compareTo" method
  // with same signature:
  // compareTo: function (other) {
  //   if(this < other) return -1;
  //   if(this > other) return  1;
  //   return 0;
  // },
  lt: function (other) {
    return this.compareTo(other) == -1;
  },
  lte: function (other) {
    return this.compareTo(other) < 1;
  },
  gt: function (other) {
    return this.compareTo(other) === 1;
  },
  gte: function (other) {
    return this.compareTo(other) > -1; 
  },
  eq: function (other) {
    return this.compareTo(other) === 0;
  },
  between: function (a, b) {
    return this.gte(a) && this.lte(b);
  }
});

// Use with Array#sort()
Comparable.sortAscending = function (a, b) {
  return a.compareTo(b);
};
Comparable.sortDescending = function (a, b) {
  return b.compareTo(a);
};
// Or you can use this helper method
Comparable.sort = function (items, direction) {
  direction = direction || "a";
  return items.sort(direction.charAt(0) == "a" ? this.sortAscending : this.sortDescending);
};