# Convert a string to a number

Use unary plus.

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

## Implementation

```javascript
function toNumber(text) { return +text; }
```

## Input

```json
"42.5"
```

## Expected output

```json
42.5
```

## Edge case

Input:
```json
""
```
Output:
```json
0
```

## Limits

- The empty string becomes 0 and invalid text becomes NaN (null in JSON). Validate first, or use Number.parseFloat for partial parsing.

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/convert-a-string-to-number.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.