splitIntoChunks

1/**
2 * Splits an array into 'n' chunks of approximately equal size.
3 * Distributes elements as evenly as possible from left to right.
4 * If the array cannot be divided equally, earlier chunks will be slightly larger.
5 *
6 * @param arr - The array to split.
7 * @param parts - Number of chunks to split into.
8 * @returns A new array of chunks.
9 */
10export function splitIntoChunks<T>(arr: T[], parts: number): T[][] {
11  if (parts <= 0) throw new Error('Number of parts must be greater than 0');
12
13  const result: T[][] = [];
14  const len = arr.length;
15  let i = 0;
16  while (i < len && parts > 0) {
17    const size = Math.ceil((len - i) / parts--);
18    result.push(arr.slice(i, i + size));
19    i += size;
20  }
21  return result;
22}

1test('splitIntoChunks - basic split', () => {
2  expect(splitIntoChunks([1, 2, 3, 4, 5], 2)).toEqual([[1, 2, 3], [4, 5]]);
3});
4
5test('splitIntoChunks - equal chunks', () => {
6  expect(splitIntoChunks([1, 2, 3, 4], 2)).toEqual([[1, 2], [3, 4]]);
7});
8
9test('splitIntoChunks - more parts than elements', () => {
10  expect(splitIntoChunks([1, 2], 5)).toEqual([[1], [2]]);
11});
12
13test('splitIntoChunks - single part', () => {
14  expect(splitIntoChunks([1, 2, 3], 1)).toEqual([[1, 2, 3]]);
15});
16
17test('splitIntoChunks - empty array', () => {
18  expect(splitIntoChunks([], 3)).toEqual([]);
19});
20
21test('splitIntoChunks - invalid parts (zero)', () => {
22  expect(() => splitIntoChunks([1, 2], 0)).toThrow('Number of parts must be greater than 0');
23});