Reverse chunk

reverse-chunk.js

const chunk = function(array, size) {
  var length = array.length;
  var index = length,
      result = Array(Math.ceil(length / size)),
      resIndex = result.length-1;

  var start;
  while (index > 0) {
    start = Math.max(0, index - size);
    result[resIndex--] = array.slice(start, index);
    index = start;
  }
  return result;
}