# Identity function

Return the argument unchanged.

Canonical: https://1loc.dev/function/identity-function/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function identity(value) { return value; }
```

## Input

```json
{
  "id": "msg_123",
  "status": "queued"
}
```

## Expected output

```json
{
  "id": "msg_123",
  "status": "queued"
}
```

## Edge case

Input:
```json
null
```
Output:
```json
null
```

## Limits

- Useful as a default transform: a pipeline step that does nothing, or values.filter(identity) to keep truthy items.
- It returns the same reference; it does not copy objects.

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/identity-function.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: See original repository history
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Curated implementation; explicit input contract, edge case and limits. Original MDX retained as inert source evidence.