# Partially apply a function

Fix the first arguments now and pass the rest later.

Canonical: https://1loc.dev/function/partially-apply-a-function/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Usage lines executed in Node.js 22 and headless Chromium; no external services
Updated: 2026-10-28

## Implementation

```javascript
function partial(fn, ...preset) { return (...rest) => fn(...preset, ...rest); }
```

## Usage

```javascript
const greet = (greeting, name) => greeting + ', ' + name;
partial(greet, 'Hello')('Ana'); // → 'Hello, Ana'
```

Lines marked → were executed in Node.js 22 and in headless Chromium, and each result was compared with the value shown. Lines marked e.g. are illustrative.

## Limits

- fn.bind(null, …preset) is the built-in equivalent for functions that do not use this.

The function does not validate its arguments. Add checks where it receives untrusted input.

## Source and license

Original: https://github.com/phuocng/1loc/blob/14b481cf60dff1620ab1bb99a43b1f68068cdd9b/contents/partially-apply-a-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: Documented as a reference with executed usage lines. Original MDX retained as inert source evidence.