takeWhile (Functional Programming)

Creates a function that takes leading values while a predicate passes. Use it with pipe.

const result = pipe(array, takeWhile(predicate));

::: info

Prefer the original es-toolkit takeWhile in ordinary code. Use this fp variant when composing transformations with pipe.

:::

Usage

takeWhile walks the piped array from the beginning and keeps values while predicate returns true. It is lazy-capable and can stop earlier lazy operations inside pipe.

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

pipe(
  [1, 2, 3, 1],
  takeWhile(value => value < 3)
); // => [1, 2]

Parameters

• predicate ((element: T, index: number) => boolean): The function that decides whether a leading value should be kept.

Returns

((array: readonly T[]) => T[]): A function that maps a readonly T[] to the leading values that pass.