uniq (Functional Programming)

Creates a function that removes duplicate values from an array. Use it with pipe.

const result = pipe(array, uniq());

::: info

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

:::

Usage

uniq returns a new array containing only unique values, preserving the order of first occurrence. Equality follows SameValueZero (the semantics of Set).

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

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

// Order of first occurrence is preserved.
pipe([3, 1, 2, 1, 3], uniq()); // => [3, 1, 2]

Parameters

This function takes no arguments; call it as uniq().

Returns

((array: readonly T[]) => T[]): A function that maps a readonly T[] to a new, duplicate-free T[].