# Invert keys and values of an object

Swap every key with its value.

Canonical: https://1loc.dev/object/invert-keys-and-values-of-an-object/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function invert(object) { return Object.fromEntries(Object.entries(object).map(([key, value]) => [value, key])); }
```

## Input

```json
{
  "delivered": "250",
  "deferred": "451"
}
```

## Expected output

```json
{
  "250": "delivered",
  "451": "deferred"
}
```

## Edge case

Input:
```json
{
  "a": "x",
  "b": "x"
}
```
Output:
```json
{
  "x": "b"
}
```

## Limits

- Values become string keys; duplicates keep the last key, as the edge case shows.

The lab validates types and size before calling this function. Add equivalent validation at your own trust boundary.

## Source and license

Original: https://github.com/phuocng/1loc/blob/14b481cf60dff1620ab1bb99a43b1f68068cdd9b/contents/invert-keys-and-values-of-an-object.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: johandalabacka
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Keeps the Object.fromEntries variant. Original MDX retained as inert source evidence.