# Capitalize a string

Uppercase the first Unicode code point and preserve the remaining text.

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

## Implementation

```javascript
function capitalize(value) { const [first, ...rest] = Array.from(value); return first ? first.toUpperCase() + rest.join('') : ''; }
```

## Input

```json
"hello, developer"
```

## Expected output

```json
"Hello, developer"
```

## Edge case

Input:
```json
""
```
Output:
```json
""
```

## Limits

- Uppercasing can expand a character, such as ß into SS. This is not locale-aware title casing.

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/capitalize-a-string.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: fahimfaisaal
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Curated implementation; explicit input bounds, edge cases, local fixtures and rebuilt presentation. Original MDX retained as inert source evidence.