uniqWith (Lodash Compatibility)

::: warning Use uniqWith from es-toolkit

This uniqWith function operates slowly due to handling of null or undefined, complex argument type processing, etc.

Instead, use the faster and more modern uniqWith from es-toolkit.

:::

Creates a new array of unique elements by removing duplicates using a comparison function.

const result = uniqWith(array, comparator);

Usage

uniqWith(array, comparator)

Removes duplicates by comparing each element of the array with a comparison function. When the comparison function returns true, the two elements are considered equal, and only the first occurring element is kept. If no comparison function is provided, it uses shallow equality comparison by default.

import { uniqWith } from 'es-toolkit/compat';

// Use without comparison function (shallow equality comparison)
uniqWith([1, 2, 2, 3]);
// Returns: [1, 2, 3]

// Remove duplicates based on odd/even criterion with custom comparison function
uniqWith([1, 2, 3, 4], (a, b) => a % 2 === b % 2);
// Returns: [1, 2]

// Remove duplicates based on property in object array
const objects = [
  { x: 1, y: 2 },
  { x: 2, y: 1 },
  { x: 1, y: 2 },
];
uniqWith(objects, (a, b) => a.x === b.x && a.y === b.y);
// Returns: [{ x: 1, y: 2 }, { x: 2, y: 1 }]

null or undefined are treated as empty arrays.

import { uniqWith } from 'es-toolkit/compat';

uniqWith(null); // []
uniqWith(undefined); // []

Parameters

• array (ArrayLike<T> | null | undefined): The array to remove duplicates from.
• comparator ((a: T, b: T) => boolean, optional): The function to compare if two elements are equal. Returns true if they are considered equal. Default is shallow equality comparison.

Returns

(T[]): Returns a new array with duplicates removed based on the comparison function result.