# Get the intersection range between two ranges

Return the overlap of two closed ranges, or an empty array.

Canonical: https://1loc.dev/number/get-the-intersection-range-between-two-ranges/
Version: 1.0.0
Runtime: JavaScript · Node.js 22 / modern browsers
Verification: Local fixtures; no external services
Updated: 2026-10-28

## Implementation

```javascript
function intersectRanges({ a, b }) { return a[0] > b[1] || a[1] < b[0] ? [] : [Math.max(a[0], b[0]), Math.min(a[1], b[1])]; }
```

## Input

```json
{
  "a": [
    1,
    10
  ],
  "b": [
    5,
    15
  ]
}
```

## Expected output

```json
[
  5,
  10
]
```

## Edge case

Input:
```json
{
  "a": [
    1,
    2
  ],
  "b": [
    3,
    4
  ]
}
```
Output:
```json
[]
```

## Limits

- Ranges are [start, end] with start ≤ end; touching ranges overlap in one point.

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/get-the-intersection-range-between-two-ranges.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.