differenceWith (Functional Programming)

Creates a function that excludes values using a custom equality function. Use it with pipe.

const result = pipe(array, differenceWith(secondArray, areItemsEqual));

INFO

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

Usage

differenceWith keeps values from the piped array only when areItemsEqual returns false for every value in secondArray.

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

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

Parameters

• secondArray (readonly U[]): The array containing values to compare against.
• areItemsEqual ((item: T, other: U) => boolean): The function that decides whether two values are equal.

Returns

((array: readonly T[]) => T[]): A function that maps a readonly T[] to values not matched by the comparator.