partition method full params for underscore.js

underscore.partition-full-params.js

var partitionIterator = function(array, n, step, pad, is_all, result) {
  if (_.size(array) < n) {
    if (_.isNull(pad) && is_all) return (_.isEmpty(array)) ? result : result.concat([array]);
    else if (!_.isNull(pad) && !is_all) return result.concat([array.concat(_.take(pad, n - _.size(array)))]);
     else return result;
   }
  else return partitionIterator(_.rest(array, step), n, step, pad, is_all, result.concat([_.take(array, n)]));
};

_.mixin({
  partition: function(array, n, step, pad) {
    var is_all = false, result = [];
    if (!_.isNumber(n)) throw new TypeError;
    if (!_.isUndefined(step) && !_.isNumber(step)) throw TypeError;
    if (!_.isUndefined(pad) && !_.isArray(pad)) throw TypeError;
    step = step ? step : n;
    pad = pad ? pad : null;
    return partitionIterator(array, n, step, pad, is_all, result);
  },
  partitionAll: function(array, n, step) {
    var pad = null, is_all = true, result = [];
    if (!_.isNumber(n)) throw new TypeError;
    if (!_.isUndefined(step) && !_.isNumber(step)) throw TypeError;
    step = step ? step : n;
    return partitionIterator(array, n, step, pad, is_all, result);
  }
});


/**
 * Refs:
 *   partition -> http://clojuredocs.org/clojure_core/clojure.core/partition
 *   partitionAll -> http://clojuredocs.org/clojure_core/clojure.core/partition-all
 */

_.partition(_.range(10), 3); // -> [[0, 1, 2], [3, 4, 5], [6, 7, 8]]
_.partition(_.range(10), 3, 2); // -> [[0, 1, 2], [2, 3, 4], [4, 5, 6], [6, 7, 8]]
_.partition(_.range(10), 4, 4, [1, 2, 3]); // -> [[0, 1, 2, 3], [4, 5, 6, 7], [8, 9, 1, 2]]
_.partitionAll(_.range(10), 3); // -> [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9]]
_.partitionAll(_.range(10), 3, 2); // -> [[0, 1, 2], [2, 3, 4], [4, 5, 6], [6, 7, 8], [8, 9]]
_.partitionAll(_.range(10), 2); //  [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9]]