# Get the first defined and non-null value

Return the first item that is neither null nor undefined.

Canonical: https://1loc.dev/misc/get-the-first-defined-and-non-null-argument/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function coalesce(values) { return values.find(item => item !== undefined && item !== null) ?? null; }
```

## Input

```json
[
  null,
  "",
  "fallback"
]
```

## Expected output

```json
""
```

## Edge case

Input:
```json
[
  null,
  null
]
```
Output:
```json
null
```

## Limits

- 0 and "" count as defined, as the example shows — unlike ||. The ?? operator does the same for two values.
- The original took rest arguments; the lab passes one array.

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/get-the-first-defined-and-non-null-argument.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: Takes one array instead of rest arguments; returns null when nothing qualifies. Original MDX retained as inert source evidence.