isSubset (Functional Programming)

Creates a function that checks whether the piped array is a subset of another array. Use it with pipe.

typescript

const result = pipe(array, isSubset(superset));

::: info

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

:::

Usage

isSubset returns true when every value in the piped array is present in superset.

typescript

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

pipe([1, 2], isSubset([1, 2, 3])); // => true

pipe([1, 4], isSubset([1, 2, 3])); // => false

superset (readonly T[]): The array that may contain all values from the piped array.

((array: readonly T[]) => boolean): A function that maps a readonly T[] to whether it is a subset.