@turf/invariant
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Lightweight utility for input validation and data extraction in Turf.js. Ensures GeoJSON inputs are in the correct format and extracts specific components like coordinates or geometries.
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# @turf/invariant
<!-- Generated by documentation.js. Update this documentation by updating the source code. -->
## getCoord
Unwrap a coordinate from a Point Feature, Geometry or a single coordinate.
### Parameters
* `coord` **([Array][1]<[number][2]> | [Geometry][3]<[Point][4]> | [Feature][5]<[Point][4]>)** GeoJSON Point or an Array of numbers
### Examples
```javascript
var pt = turf.point([10, 10]);
var coord = turf.getCoord(pt);
//= [10, 10]
```
Returns **[Array][1]<[number][2]>** coordinates
## getCoords
Unwrap coordinates from a Feature, Geometry Object or an Array
### Parameters
* `coords` **([Array][1]\<any> | [Geometry][3] | [Feature][5])** Feature, Geometry Object or an Array
### Examples
```javascript
var poly = turf.polygon([[[119.32, -8.7], [119.55, -8.69], [119.51, -8.54], [119.32, -8.7]]]);
var coords = turf.getCoords(poly);
//= [[[119.32, -8.7], [119.55, -8.69], [119.51, -8.54], [119.32, -8.7]]]
```
Returns **[Array][1]\<any>** coordinates
## containsNumber
Checks if coordinates contains a number
### Parameters
* `coordinates` **[Array][1]\<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.
Returns **void** 
## featureOf
Enforce expectations about types of [Feature][5] inputs for Turf.
Internally this uses [geojsonType][10] 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.
Returns **void** 
## collectionOf
Enforce expectations about types of [FeatureCollection][11] inputs for Turf.
Internally this uses [geojsonType][10] to judge geometry types.
### Parameters
* `featureCollection` **[FeatureCollection][11]** 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
## getType
Get GeoJSON object's type, Geometry type is prioritize.
### Parameters
* `geojson` **[GeoJSON][7]** GeoJSON object
* `_name` **[string][8]?** 
* `name` **[string][8]** name of the variable to display in error message (unused) (optional, default `"geojson"`)
### 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]: #geojsontype
[11]: https://tools.ietf.org/html/rfc7946#section-3.3
<!-- This file is automatically generated. Please don't edit it directly. If you find an error, edit the source file of the module in question (likely index.js or index.ts), and re-run "yarn docs" from the root of the turf project. -->
---
This module is part of the [Turfjs project](https://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 single module individually:
```sh
$ npm install @turf/invariant
```
Or install the all-encompassing @turf/turf module that includes all modules as functions:
```sh
$ npm install @turf/turf
```