mapValues

Creates a new object with the same keys as obj, but with each value replaced by iteratee(value, key, obj). Only own enumerable string keys are visited. Useful for projecting an object through a pure transformation while preserving its shape.

Try it

Import

import { mapValues } from "1o1-utils";

import { mapValues } from "1o1-utils/map-values";

Signature

function mapValues<T extends Record<string, unknown>, R>({
  obj,
  iteratee,
}: MapValuesParams<T, R>): Record<keyof T, R>

Parameters

Name	Type	Required	Description
obj	Record<string, unknown>	Yes	The source object
iteratee	(value, key, obj) => R	Yes	Function returning the new value for each pair

Returns

Record<keyof T, R> — A new object with the same keys and transformed values (input is not mutated).

Examples

mapValues({
  obj: { a: 1, b: 2 },
  iteratee: (value) => value * 10,
});
// => { a: 10, b: 20 }

mapValues({
  obj: { ana: { age: 30 }, bob: { age: 25 } },
  iteratee: (user) => user.age,
});
// => { ana: 30, bob: 25 }

Edge Cases

• Throws if obj is not a plain object.
• Throws if iteratee is not a function.
• Inherited properties are ignored — only own enumerable keys are visited.
• Output type can differ from input value type (full generic support).

Also known as

map values, transform values, value mapper, project values

Prompt suggestion

I'm using 1o1-utils (npm: https://www.npmjs.com/package/1o1-utils, GitHub: https://github.com/pedrotroccoli/1o1-utils, LLM context: https://pedrotroccoli.github.io/1o1-utils/llms.txt). Show me how to use mapValues to extract a single field from each value of a record