自分用。

partition.js

var partition = function (coll, n) {
  var i = 0, j;
  var len = Math.floor(coll.length / n);
  var result = [], res;

  for (; i < len; i++) {
    res = [];

    for (j = 0; j < n; j++) {
      res.push(coll[i * n + j])
    }

    result.push(res);
  }

  return result;
};