isSubsetWith (Functional Programming)

Creates a function that checks subset membership using a custom equality function. Use it with pipe.

const result = pipe(array, isSubsetWith(superset, areItemsEqual));

INFO

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

Usage

isSubsetWith returns true when every value in the piped array matches at least one value in superset according to areItemsEqual.

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

pipe(
  [{ id: 1 }],
  isSubsetWith([{ id: 1 }, { id: 2 }], (a, b) => a.id === b.id)
); // => true

Parameters

• superset (readonly T[]): The array that may contain all values from the piped array.
• areItemsEqual ((item: T, other: T) => boolean): The function that decides whether two values are equal.

Returns

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