chunkBy (Functional Programming)

Creates a function that splits adjacent values whenever a key changes. Use it with pipe.

const result = pipe(array, chunkBy(iteratee));

::: info

This helper is specific to es-toolkit/fp. Use it when you want this operation as part of a pipe pipeline.

:::

Usage

chunkBy walks the piped array from left to right and groups adjacent values while iteratee returns the same key. A new chunk starts when the key changes.

import { chunkBy, pipe } from 'es-toolkit/fp';

pipe(
  [1, 1, 2, 2, 1],
  chunkBy(value => value)
); // => [[1, 1], [2, 2], [1]]

Parameters

• iteratee ((value: T) => unknown): The function that returns the grouping key for each value.

Returns

((array: readonly T[]) => T[][]): A function that maps a readonly T[] to chunks of adjacent values.