For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt, and this page is available as Markdown at /reference/object/mapKeys.md.
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    mapKeys es-toolkit

    Returns a new object with keys transformed through a function.

    const newObj = mapKeys(object, getNewKey);

    Usage

    mapKeys(object, getNewKey)

    Use mapKeys when you want to create a new object by transforming each key. Values remain the same, and only the keys are changed to the results of the getNewKey function.

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

// Add prefix to keys
const obj = { a: 1, b: 2 };
const prefixed = mapKeys(obj, (value, key) => `prefix_${key}`);
// prefixed becomes { prefix_a: 1, prefix_b: 2 }

// Combine key and value to create new keys
const combined = mapKeys(obj, (value, key) => `${key}${value}`);
// combined becomes { a1: 1, b2: 2 }

// Convert keys to uppercase
const uppercased = mapKeys(obj, (value, key) => key.toString().toUpperCase());
// uppercased becomes { A: 1, B: 2 }

    Parameters

    objectT extends Record<PropertyKey, any>required

    The object to transform keys from.

    getNewKey(value: T[keyof T], key: keyof T, object: T) => Krequired

    A function that generates new keys. Receives value, key, and the entire object as parameters.

    Returns

    Returns a new object with transformed keys.

    Record<K, T[keyof T]>
    Source: es-toolkit

    Re-exported verbatim from es-toolkit. Implementation, edge cases, and performance behavior are owned upstream. This page mirrors the documentation at the pinned version; the linked source is authoritative.