uniqBy (Lodash Compatibility)

Use uniqBy from es-toolkit

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

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

Creates a new array of unique elements by removing duplicates based on the values returned by a transformation function.

const result = uniqBy(array, iteratee);

Reference

uniqBy(array, iteratee)

Applies a transformation function to each element of the array and keeps only the first element among those with the same transformation result. This is useful when removing duplicates based on a specific property in an object array or based on a specific calculation result in a number array.

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

// Remove duplicates by Math.floor result in number array
uniqBy([2.1, 1.2, 2.3], Math.floor);
// Returns: [2.1, 1.2]

// Remove duplicates by property in object array
uniqBy([{ x: 1 }, { x: 2 }, { x: 1 }], 'x');
// Returns: [{ x: 1 }, { x: 2 }]

// Remove duplicates with function
uniqBy([{ name: 'John' }, { name: 'Jane' }, { name: 'John' }], obj => obj.name);
// Returns: [{ name: 'John' }, { name: 'Jane' }]

null or undefined are treated as empty arrays.

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

uniqBy(null, Math.floor); // []
uniqBy(undefined, 'x'); // []

Parameters

• array (ArrayLike<T> | null | undefined): The array to remove duplicates from.
• iteratee (ValueIteratee<T>): The transformation function to apply to each element. Can be a function, property name, partial object, etc.

Returns

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