# Create cartesian product

Combine one item from each set in every possible way.

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

## Implementation

```javascript
function cartesian(sets) { return sets.reduce((product, set) => product.flatMap(prefix => set.map(item => [...prefix, item])), [[]]); }
```

## Input

```json
[
  [
    "node",
    "curl"
  ],
  [
    "sandbox",
    "live"
  ]
]
```

## Expected output

```json
[
  [
    "node",
    "sandbox"
  ],
  [
    "node",
    "live"
  ],
  [
    "curl",
    "sandbox"
  ],
  [
    "curl",
    "live"
  ]
]
```

## Edge case

Input:
```json
[]
```
Output:
```json
[
  []
]
```

## Limits

- The result size is the product of the set sizes; the lab caps it at 1,000 combinations.
- The original took sets as separate arguments.

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/create-cartesian-product.mdx
Source file (this edition): https://github.com/akamind/1loc/blob/0a77f131b22d2ba3b7ec1728846f900c22821678/contents/create-cartesian-product.mdx
Author: Nguyen Huu Phuoc and original contributors
Contributors: robinpokorny
Source commit: 14b481cf60dff1620ab1bb99a43b1f68068cdd9b
Copyright (c) 2020 phuoc-ng
License: MIT — https://1loc.dev/licenses/
Maintainer: Oveyon
Modifications: Takes one array of sets; caps the product size before allocating. Original MDX retained as inert source evidence.