Transform an array to some chunk array.

_.chunk.js

function chunk(arr, chunk) {
  var res = [],
      len = arr.length,
      _len = Math.ceil(arr.length / chunk),
      _chunk = 0;
  chunk = chunk > len ? len : chunk;

  for (var i = 0; i < _len ;i++) {
    var _arr = [];

    if (i === _len - 1 && chunk > _len) {
      for (var j = 0; j < (len - chunk); j++) {
        _arr.push(arr[_chunk + j]);
      }
    } else {
      for (var j = 0; j < chunk; j++) {
        _arr.push(arr[_chunk + j]);
      }
    }

    _chunk = chunk + _chunk;
    res.push(_arr);
  }

  return res;
}