@spatial/invariant/README.md

turf invariant module

# @spatial/invariant

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## getCoord

Unwrap a coordinate from a Point Feature, Geometry or a single coordinate.

### Parameters

-   `obj` **([Array][1]&lt;[number][2]> | [Geometry][3]&lt;[Point][4]> | [Feature][5]&lt;[Point][4]>)** Object

### Examples

```javascript
var pt = turf.point([10, 10]);

var coord = turf.getCoord(pt);
//= [10, 10]
```

Returns **[Array][1]&lt;[number][2]>** coordinates

## getCoords

Unwrap coordinates from a Feature, Geometry Object or an Array of numbers

### Parameters

-   `obj` **([Array][1]&lt;[number][2]> | [Geometry][3] \| [Feature][5])** Object

### Examples

```javascript
var poly = turf.polygon([[[119.32, -8.7], [119.55, -8.69], [119.51, -8.54], [119.32, -8.7]]]);

var coord = turf.getCoords(poly);
//= [[[119.32, -8.7], [119.55, -8.69], [119.51, -8.54], [119.32, -8.7]]]
```

Returns **[Array][1]&lt;[number][2]>** coordinates

## containsNumber

Checks if coordinates contains a number

### Parameters

-   `coordinates` **[Array][1]&lt;any>** GeoJSON Coordinates

Returns **[boolean][6]** true if Array contains a number

## geojsonType

Enforce expectations about types of GeoJSON objects for Turf.

### Parameters

-   `value` **[GeoJSON][7]** any GeoJSON object
-   `type` **[string][8]** expected GeoJSON type
-   `name` **[string][8]** name of calling function


-   Throws **[Error][9]** if value is not the expected type.

## featureOf

Enforce expectations about types of [Feature][10] inputs for Turf.
Internally this uses [geojsonType][11] to judge geometry types.

### Parameters

-   `feature` **[Feature][5]** a feature with an expected geometry type
-   `type` **[string][8]** expected GeoJSON type
-   `name` **[string][8]** name of calling function


-   Throws **[Error][9]** error if value is not the expected type.

## collectionOf

Enforce expectations about types of [FeatureCollection][12] inputs for Turf.
Internally this uses [geojsonType][11] to judge geometry types.

### Parameters

-   `featureCollection` **[FeatureCollection][13]** a FeatureCollection for which features will be judged
-   `type` **[string][8]** expected GeoJSON type
-   `name` **[string][8]** name of calling function


-   Throws **[Error][9]** if value is not the expected type.

## getGeom

Get Geometry from Feature or Geometry Object

### Parameters

-   `geojson` **([Feature][5] \| [Geometry][3])** GeoJSON Feature or Geometry Object

### Examples

```javascript
var point = {
  "type": "Feature",
  "properties": {},
  "geometry": {
    "type": "Point",
    "coordinates": [110, 40]
  }
}
var geom = turf.getGeom(point)
//={"type": "Point", "coordinates": [110, 40]}
```

-   Throws **[Error][9]** if geojson is not a Feature or Geometry Object

Returns **([Geometry][3] | null)** GeoJSON Geometry Object

## getGeomType

Get Geometry Type from Feature or Geometry Object

-   Throws **[Error][9]** **DEPRECATED** in v5.0.0 in favor of getType

## getType

Get GeoJSON object's type, Geometry type is prioritize.

### Parameters

-   `geojson` **[GeoJSON][7]** GeoJSON object
-   `name` **[string][8]?** name of the variable to display in error message

### Examples

```javascript
var point = {
  "type": "Feature",
  "properties": {},
  "geometry": {
    "type": "Point",
    "coordinates": [110, 40]
  }
}
var geom = turf.getType(point)
//="Point"
```

Returns **[string][8]** GeoJSON type

[1]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array

[2]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number

[3]: https://tools.ietf.org/html/rfc7946#section-3.1

[4]: https://tools.ietf.org/html/rfc7946#section-3.1.2

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

[6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean

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

[8]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String

[9]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Error

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

[11]: #geojsontype

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

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

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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 @spatial/invariant
```

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

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