mapKeys (Lodash compatibility)

Use mapKeys from es-toolkit

This mapKeys function is relatively slow due to handling null or undefined and the iteratee conversion process.

Use the faster and more modern mapKeys from es-toolkit instead.

Creates a new object by transforming keys while keeping values the same.

const result = mapKeys(obj, iteratee);

Reference

mapKeys(object, iteratee)

Transforms each key in an object using the iteratee function to create a new object. Values remain unchanged while only keys are modified. Useful for transforming or normalizing object keys.

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

// Add prefix to keys
const obj = { a: 1, b: 2, c: 3 };
const result = mapKeys(obj, (value, key) => 'prefix_' + key);
// Result: { prefix_a: 1, prefix_b: 2, prefix_c: 3 }

// Convert keys to uppercase
const data = { name: 'John', age: 30 };
const uppercased = mapKeys(data, (value, key) => key.toUpperCase());
// Result: { NAME: 'John', AGE: 30 }

// Convert array indices to keys
const arr = ['apple', 'banana', 'orange'];
const indexed = mapKeys(arr, (value, index) => `item_${index}`);
// Result: { item_0: 'apple', item_1: 'banana', item_2: 'orange' }

// Create new keys by combining key and value
const scores = { math: 90, science: 85, english: 92 };
const detailed = mapKeys(scores, (value, key) => `${key}_score_${value}`);
// Result: { math_score_90: 90, science_score_85: 85, english_score_92: 92 }

null or undefined are treated as empty objects.

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

mapKeys(null, iteratee); // {}
mapKeys(undefined, iteratee); // {}

Parameters

• object (ArrayLike<T> | T | null | undefined): The object or array to transform keys from.
• iteratee (ListIteratee<T> | ObjectIteratee<T>, optional): The function to transform each key. Defaults to the identity function.

Returns

(Record<string, T> | Record<string, T[keyof T]>): Returns a new object with transformed keys.