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30-seconds-of-code/snippets/mapValues.md
30secondsofcode 3414134ee7 Travis build: 1194
2018-01-11 18:34:38 +00:00

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### mapValues
Creates an object with the same keys as the provided object and values generated by running the provided function for each value.
Use `Object.keys(obj)` to iterate over the object's keys.
Use `Array.reduce()` to create a new object with the same keys and mapped values using `fn`.
```js
const mapValues = (obj, fn) =>
Object.keys(obj).reduce((acc, k) => {
acc[k] = fn(obj[k], k, obj);
return acc;
}, {});
```
```js
const users = {
fred: { user: 'fred', age: 40 },
pebbles: { user: 'pebbles', age: 1 }
};
mapValues(users, u => u.age); // { fred: 40, pebbles: 1 }
```