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

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### mapKeys
Creates an object with keys generated by running the provided function for each key and the same values as the provided object.
Use `Object.keys(obj)` to iterate over the object's keys.
Use `Array.reduce()` to create a new object with the same values and mapped keys using `fn`.
```js
const mapKeys = (obj, fn) =>
Object.keys(obj).reduce((acc, k) => {
acc[fn(obj[k], k, obj)] = obj[k];
return acc;
}, {});
```
```js
mapKeys({ a: 1, b: 2 }, (val, key) => key + val); // { a1: 1, b2: 2 }
```