froebel/batch.mjs

TypeScript utility library

import { assert } from "./except.mjs";
/**
 * Takes a `list` and returns it in multiple smaller lists of the size
 * `batchSize`.
 * The last batch may be smaller than `batchSize` depending on if `list` size is
 * divisible by `batchSize`.
 *
 * @example
 * ```
 * batch([1,2,3,4,5], 2)  // -> [ [1,2], [3,4], [5] ]
 * ```
 */

const batch = (list, batchSize) => {
  assert(typeof batchSize === "number" && !Number.isNaN(batchSize) && batchSize > 0, "batch size must be > 0", RangeError);
  const size = Number.isFinite(batchSize) ? batchSize : list.length;
  return [...Array(Math.ceil(list.length / size))].map((_, i) => list.slice(i * size, (i + 1) * size));
};

export default batch;