keyBy (Lodash Compatibility)

Use es-toolkit's keyBy

This keyBy function is slow due to handling null or undefined, various parameter types, etc.

Use the faster and more modern es-toolkit's keyBy instead.

Organizes collection elements into an object based on the specified key.

const result = keyBy(collection, iteratee);

Reference

keyBy(collection, iteratee)

Organizes each element in an array or object into an object using the specified key generation function or property name. If multiple elements have the same key, the last element is used.

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

// Generate keys by property name
const array = [
  { dir: 'left', code: 97 },
  { dir: 'right', code: 100 },
];

keyBy(array, 'dir');
// => { left: { dir: 'left', code: 97 }, right: { dir: 'right', code: 100 } }

// Generate keys using a function
keyBy(array, o => String.fromCharCode(o.code));
// => { a: { dir: 'left', code: 97 }, d: { dir: 'right', code: 100 } }

// Can also be used with objects
const obj = {
  a: { id: 1, name: 'john' },
  b: { id: 2, name: 'jane' },
};
keyBy(obj, 'name');
// => { john: { id: 1, name: 'john' }, jane: { id: 2, name: 'jane' } }

null or undefined are treated as empty objects.

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

keyBy(null, 'id'); // {}
keyBy(undefined, 'id'); // {}

Parameters

• collection (ArrayLike<T> | null | undefined): The array or object to organize by key.
• iteratee (ValueIterateeCustom<T, PropertyKey>, optional): The function or property name to generate keys. If omitted, the element itself is used as the key.

Returns

(Record<string, T>): Returns a new object where each element is mapped to the generated key.