@turf/invariant
Advanced tools
@turf/invariant is a module within the Turf.js library that provides utility functions for validating and extracting GeoJSON objects. It ensures that the input data conforms to the expected GeoJSON format, which is crucial for performing various geospatial operations.
getCoord
The `getCoord` function extracts the coordinates from a GeoJSON Point feature. This is useful when you need to work directly with the coordinates of a point.
const turf = require('@turf/invariant');
const point = { type: 'Feature', geometry: { type: 'Point', coordinates: [102.0, 0.5] } };
const coord = turf.getCoord(point);
console.log(coord); // [102.0, 0.5]getCoords
The `getCoords` function extracts the coordinates from a GeoJSON LineString or Polygon feature. This is useful for accessing the array of coordinates that make up the geometry.
const turf = require('@turf/invariant');
const line = { type: 'Feature', geometry: { type: 'LineString', coordinates: [[102.0, 0.0], [103.0, 1.0]] } };
const coords = turf.getCoords(line);
console.log(coords); // [[102.0, 0.0], [103.0, 1.0]]getGeom
The `getGeom` function extracts the geometry object from a GeoJSON feature. This is useful when you need to work with the geometry independently of the feature properties.
const turf = require('@turf/invariant');
const feature = { type: 'Feature', geometry: { type: 'Polygon', coordinates: [[[102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [102.0, 0.0]]] } };
const geom = turf.getGeom(feature);
console.log(geom); // { type: 'Polygon', coordinates: [[[102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [102.0, 0.0]]] }getType
The `getType` function returns the type of a GeoJSON object. This is useful for validating the type of geometry you are working with.
const turf = require('@turf/invariant');
const feature = { type: 'Feature', geometry: { type: 'Polygon', coordinates: [[[102.0, 0.0], [103.0, 1.0], [104.0, 0.0], [102.0, 0.0]]] } };
const type = turf.getType(feature);
console.log(type); // 'Polygon'The `geojson-validation` package provides functions to validate GeoJSON objects against the GeoJSON specification. It is similar to @turf/invariant in that it ensures the input data conforms to the expected GeoJSON format, but it focuses more on validation rather than extraction of specific components.
The `geojson-utils` package offers a set of utility functions for working with GeoJSON data, including validation, distance calculations, and bounding box operations. It provides broader functionality compared to @turf/invariant, which is more focused on validation and extraction.
Unwrap a coordinate from a Point Feature, Geometry or a single coordinate.
Parameters
Examples
var pt = turf.point([10, 10]);
var coord = turf.getCoord(pt);
//= [10, 10]
Returns Array<number> coordinates
Unwrap coordinates from a Feature, Geometry Object or an Array of numbers
Parameters
Examples
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<number> coordinates
Checks if coordinates contains a number
Parameters
coordinates Array<any> GeoJSON CoordinatesReturns boolean true if Array contains a number
Enforce expectations about types of GeoJSON objects for Turf.
Parameters
value GeoJSON any GeoJSON object
type string expected GeoJSON type
name string name of calling function
Throws Error if value is not the expected type.
Enforce expectations about types of Feature inputs for Turf. Internally this uses geojsonType to judge geometry types.
Parameters
feature Feature a feature with an expected geometry type
type string expected GeoJSON type
name string name of calling function
Throws Error error if value is not the expected type.
Enforce expectations about types of FeatureCollection inputs for Turf. Internally this uses geojsonType to judge geometry types.
Parameters
featureCollection FeatureCollection a FeatureCollection for which features will be judged
type string expected GeoJSON type
name string name of calling function
Throws Error if value is not the expected type.
Get Geometry from Feature or Geometry Object
Parameters
Examples
var point = {
"type": "Feature",
"properties": {},
"geometry": {
"type": "Point",
"coordinates": [110, 40]
}
}
var geom = turf.getGeom(point)
//={"type": "Point", "coordinates": [110, 40]}
Returns (Geometry | null) GeoJSON Geometry Object
Get Geometry Type from Feature or Geometry Object DEPRECATED in v5.0.0 in favor of getType
Parameters
geojson (Feature | Geometry) GeoJSON Feature or Geometry Objectname [string] name of the variable to display in error messageExamples
var point = {
"type": "Feature",
"properties": {},
"geometry": {
"type": "Point",
"coordinates": [110, 40]
}
}
var geom = turf.getGeomType(point)
//="Point"
Returns string GeoJSON Geometry Type
Get GeoJSON object's type, Geometry type is prioritize.
Parameters
Examples
var point = {
"type": "Feature",
"properties": {},
"geometry": {
"type": "Point",
"coordinates": [110, 40]
}
}
var geom = turf.getType(point)
//="Point"
Returns string GeoJSON type
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.
Install this module individually:
$ npm install @turf/invariant
Or install the Turf module that includes it as a function:
$ npm install @turf/turf
FAQs
turf invariant module
The npm package @turf/invariant receives a total of 176,592 weekly downloads. As such, @turf/invariant popularity was classified as popular.
We found that @turf/invariant demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 9 open source maintainers collaborating on the project.
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