21-Chunk.js

/**
 * @param {Array} arr
 * @param {number} size
 * @return {Array[]}
 */
var chunk = function(arr, size) {
  const result = []
  for (let i = 0; i < arr.length; i += size) {
      result.push(arr.slice(i, i + size))
  }
  return result
};