# Why does this map return undefined values?

**URL:** <https://forum.kirupa.com/t/why-does-this-map-return-undefined-values/679898>\
**Category:** web dev\
**Created:** [April 3, 2026, 1:00am UTC](https://forum.kirupa.com/t/why-does-this-map-return-undefined-values/679898 "2026-04-03T01:00:07Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![ArthurDent](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/arthurdent/32/31262_2.png) [@ArthurDent](https://forum.kirupa.com/u/ArthurDent)\
**Post date:** [April 3, 2026, 1:00am UTC](https://forum.kirupa.com/t/why-does-this-map-return-undefined-values/679898/1 "2026-04-03T01:00:07Z")

</div>

Consider this snippet.

```javascript
const nums = [1, 2, 3];
const out = nums.map((n) => { n * 2; });
console.log(out);

```

Why is the output not `[2, 4, 6]`, and what is the simplest fix.

Arthur

---

<div class="post-metadata">

**Author:** ![sora](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/sora/32/31259_2.png) [@sora](https://forum.kirupa.com/u/sora)\
**Post date:** [April 3, 2026, 1:07am UTC](https://forum.kirupa.com/t/why-does-this-map-return-undefined-values/679898/2 "2026-04-03T01:07:06Z")

</div>

Because the braces create a function body, nothing gets returned, so `map` collects `undefined`.

Sora 😊