# @turf/difference

# difference

Finds the difference between two [polygons](http://geojson.org/geojson-spec.html#polygon) by clipping the second polygon from the first.

**Parameters**

-   `polygon1` **[Feature](http://geojson.org/geojson-spec.html#feature-objects)<([Polygon](http://geojson.org/geojson-spec.html#polygon) \| [MultiPolygon](http://geojson.org/geojson-spec.html#multipolygon))>** input Polygon feature
-   `polygon2` **[Feature](http://geojson.org/geojson-spec.html#feature-objects)<([Polygon](http://geojson.org/geojson-spec.html#polygon) \| [MultiPolygon](http://geojson.org/geojson-spec.html#multipolygon))>** Polygon feature to difference from polygon1

**Examples**

```javascript
var polygon1 = turf.polygon([[
  [128, -26],
  [141, -26],
  [141, -21],
  [128, -21],
  [128, -26]
]], {
  "fill": "#F00",
  "fill-opacity": 0.1
});
var polygon2 = turf.polygon([[
  [126, -28],
  [140, -28],
  [140, -20],
  [126, -20],
  [126, -28]
]], {
  "fill": "#00F",
  "fill-opacity": 0.1
});

var difference = turf.difference(polygon1, polygon2);

//addToMap
var addToMap = [polygon1, polygon2, difference];
```

Returns **([Feature](http://geojson.org/geojson-spec.html#feature-objects)<([Polygon](http://geojson.org/geojson-spec.html#polygon) \| [MultiPolygon](http://geojson.org/geojson-spec.html#multipolygon))> | [null](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/null))** a Polygon or MultiPolygon feature showing the area of `polygon1` excluding the area of `polygon2` (if empty returns `null`)

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---

This module is part of the [Turfjs project](http://turfjs.org/), an open source
module collection dedicated to geographic algorithms. It is maintained in the
[Turfjs/turf](https://github.com/Turfjs/turf) repository, where you can create
PRs and issues.

### Installation

Install this module individually:

```sh
$ npm install @turf/difference
```

Or install the Turf module that includes it as a function:

```sh
$ npm install @turf/turf
```