@turf/difference

difference

Finds the difference between multiple [polygons][1] by clipping the subsequent polygon from the first.

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* features [FeatureCollection][2]<([Polygon][1] | [MultiPolygon][3])> input Polygon features

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``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(turf.featureCollection([polygon1, polygon2]));

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

Returns ([Feature][4]<([Polygon][1] | [MultiPolygon][3])> | null) a Polygon or MultiPolygon feature showing the area of polygon1 excluding the area of polygon2 (if empty returns null)

[1]: https://tools.ietf.org/html/rfc7946#section-3.1.6

[2]: https://tools.ietf.org/html/rfc7946#section-3.3

[3]: https://tools.ietf.org/html/rfc7946#section-3.1.7

[4]: https://tools.ietf.org/html/rfc7946#section-3.2

---

This module is part of the Turfjs project, an open source module collection dedicated to geographic algorithms. It is maintained in the Turfjs/turf repository, where you can create PRs and issues.

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Install this single module individually:

`sh
$ npm install @turf/difference
`

Or install the all-encompassing @turf/turf module that includes all modules as functions:

`sh
$ npm install @turf/turf
``