js求笛卡尔积

[RainZhai]

  cartesian() {
    return Array.prototype.reduce.call(arguments, function (a, b) {
      var ret = [];
      a.forEach(function (a) {
        b.forEach(function (b) {
          ret.push(a.concat([b]));
        });
      });
      return ret;
    }, [[]]);
  }