function chunk(array, size) {

  let result = [];

  let temp = [];

  const len = array.length;

  for (let i = 0; i < len; i++) {

    let mod = i % size;

    if (mod === 0) {

      if (temp.length !== 0) {

        result = [...result, temp];

      }

      temp = [];

    }

    temp[mod] = array[i];

  }

  result = [...result, temp];

  return result;

}

function chunk(array, size) {

  let chunked = [];

  let index = 0;

  while (index < array.length) {

    chunked.push(array.slice(index, index + size));

    index += size;

  }

  return chunked;

}

const chunk = require("./index");

test("function chunk exists", () => {

  expect(typeof chunk).toEqual("function");

});

test("chunk divides an array of 10 elements with chunk size 2", () => {

  const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

  const chunked = chunk(arr, 2);

  expect(chunked).toEqual([[1, 2], [3, 4], [5, 6], [7, 8], [9, 10]]);

});

test("chunk divides an array of 3 elements with chunk size 1", () => {

  const arr = [1, 2, 3];

  const chunked = chunk(arr, 1);

  expect(chunked).toEqual([[1], [2], [3]]);

});

test("chunk divides an array of 5 elements with chunk size 3", () => {

  const arr = [1, 2, 3, 4, 5];

  const chunked = chunk(arr, 3);

  expect(chunked).toEqual([[1, 2, 3], [4, 5]]);

});

test("chunk divides an array of 13 elements with chunk size 5", () => {

  const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13];

  const chunked = chunk(arr, 5);

  expect(chunked).toEqual([[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13]]);

});