# Check if a string is a MongoDB ObjectId

Test for exactly 24 hexadecimal characters.

Canonical: https://1loc.dev/validator/check-if-a-string-is-a-mongo-db-object-id/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function isMongoId(text) { return /^[0-9a-f]{24}$/i.test(text); }
```

## Input

```json
"507f1f77bcf86cd799439011"
```

## Expected output

```json
true
```

## Edge case

Input:
```json
"507f1f77bcf86cd79943901z"
```
Output:
```json
false
```

## Limits

- This checks the format only, not that the document exists.

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/check-if-a-string-is-a-mongo-db-object-id.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: Single anchored regular expression for the 24-character length and alphabet. Original MDX retained as inert source evidence.