@spatial/invariant/index.js

turf invariant module

import { isNumber } from '@spatial/helpers';

/**
 * Unwrap a coordinate from a Point Feature, Geometry or a single coordinate.
 *
 * @name getCoord
 * @param {Array<number>|Geometry<Point>|Feature<Point>} obj Object
 * @returns {Array<number>} coordinates
 * @example
 * var pt = turf.point([10, 10]);
 *
 * var coord = turf.getCoord(pt);
 * //= [10, 10]
 */
export function getCoord(obj) {
    if (!obj) throw new Error('obj is required');

    const coordinates = getCoords(obj);

    // getCoord() must contain at least two numbers (Point)
    if (coordinates.length > 1 && isNumber(coordinates[0]) && isNumber(coordinates[1])) {
        return coordinates;
    } else {
        throw new Error('Coordinate is not a valid Point');
    }
}

/**
 * Unwrap coordinates from a Feature, Geometry Object or an Array of numbers
 *
 * @name getCoords
 * @param {Array<number>|Geometry|Feature} obj Object
 * @returns {Array<number>} coordinates
 * @example
 * 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]]]
 */
export function getCoords(obj) {
    if (!obj) throw new Error('obj is required');
    let coordinates;

    // Array of numbers
    if (obj.length) {
        coordinates = obj;

    // Geometry Object
    } else if (obj.coordinates) {
        coordinates = obj.coordinates;

    // Feature
    } else if (obj.geometry && obj.geometry.coordinates) {
        coordinates = obj.geometry.coordinates;
    }
    // Checks if coordinates contains a number
    if (coordinates) {
        containsNumber(coordinates);
        return coordinates;
    }
    throw new Error('No valid coordinates');
}

/**
 * Checks if coordinates contains a number
 *
 * @name containsNumber
 * @param {Array<any>} coordinates GeoJSON Coordinates
 * @returns {boolean} true if Array contains a number
 */
export function containsNumber(coordinates) {
    if (coordinates.length > 1 && isNumber(coordinates[0]) && isNumber(coordinates[1])) {
        return true;
    }

    if (Array.isArray(coordinates[0]) && coordinates[0].length) {
        return containsNumber(coordinates[0]);
    }
    throw new Error('coordinates must only contain numbers');
}

/**
 * Enforce expectations about types of GeoJSON objects for Turf.
 *
 * @name geojsonType
 * @param {GeoJSON} value any GeoJSON object
 * @param {string} type expected GeoJSON type
 * @param {string} name name of calling function
 * @throws {Error} if value is not the expected type.
 */
export function geojsonType(value, type, name) {
    if (!type || !name) throw new Error('type and name required');

    if (!value || value.type !== type) {
        throw new Error(`Invalid input to ${  name  }: must be a ${  type  }, given ${  value.type}`);
    }
}

/**
 * Enforce expectations about types of {@link Feature} inputs for Turf.
 * Internally this uses {@link geojsonType} to judge geometry types.
 *
 * @name featureOf
 * @param {Feature} feature a feature with an expected geometry type
 * @param {string} type expected GeoJSON type
 * @param {string} name name of calling function
 * @throws {Error} error if value is not the expected type.
 */
export function featureOf(feature, type, name) {
    if (!feature) throw new Error('No feature passed');
    if (!name) throw new Error('.featureOf() requires a name');
    if (!feature || feature.type !== 'Feature' || !feature.geometry) {
        throw new Error(`Invalid input to ${  name  }, Feature with geometry required`);
    }
    if (!feature.geometry || feature.geometry.type !== type) {
        throw new Error(`Invalid input to ${  name  }: must be a ${  type  }, given ${  feature.geometry.type}`);
    }
}

/**
 * Enforce expectations about types of {@link FeatureCollection} inputs for Turf.
 * Internally this uses {@link geojsonType} to judge geometry types.
 *
 * @name collectionOf
 * @param {FeatureCollection} featureCollection a FeatureCollection for which features will be judged
 * @param {string} type expected GeoJSON type
 * @param {string} name name of calling function
 * @throws {Error} if value is not the expected type.
 */
export function collectionOf(featureCollection, type, name) {
    if (!featureCollection) throw new Error('No featureCollection passed');
    if (!name) throw new Error('.collectionOf() requires a name');
    if (!featureCollection || featureCollection.type !== 'FeatureCollection') {
        throw new Error(`Invalid input to ${  name  }, FeatureCollection required`);
    }
    for (let i = 0; i < featureCollection.features.length; i++) {
        const feature = featureCollection.features[i];
        if (!feature || feature.type !== 'Feature' || !feature.geometry) {
            throw new Error(`Invalid input to ${  name  }, Feature with geometry required`);
        }
        if (!feature.geometry || feature.geometry.type !== type) {
            throw new Error(`Invalid input to ${  name  }: must be a ${  type  }, given ${  feature.geometry.type}`);
        }
    }
}

/**
 * Get Geometry from Feature or Geometry Object
 *
 * @param {Feature|Geometry} geojson GeoJSON Feature or Geometry Object
 * @returns {Geometry|null} GeoJSON Geometry Object
 * @throws {Error} if geojson is not a Feature or Geometry Object
 * @example
 * var point = {
 *   "type": "Feature",
 *   "properties": {},
 *   "geometry": {
 *     "type": "Point",
 *     "coordinates": [110, 40]
 *   }
 * }
 * var geom = turf.getGeom(point)
 * //={"type": "Point", "coordinates": [110, 40]}
 */
export function getGeom(geojson) {
    if (!geojson) throw new Error('geojson is required');
    if (geojson.geometry !== undefined) return geojson.geometry;
    if (geojson.coordinates || geojson.geometries) return geojson;
    throw new Error('geojson must be a valid Feature or Geometry Object');
}

/**
 * Get Geometry Type from Feature or Geometry Object
 *
 * @throws {Error} **DEPRECATED** in v5.0.0 in favor of getType
 */
export function getGeomType() {
    throw new Error('invariant.getGeomType has been deprecated in v5.0 in favor of invariant.getType');
}

/**
 * Get GeoJSON object's type, Geometry type is prioritize.
 *
 * @param {GeoJSON} geojson GeoJSON object
 * @param {string} [name] name of the variable to display in error message
 * @returns {string} GeoJSON type
 * @example
 * var point = {
 *   "type": "Feature",
 *   "properties": {},
 *   "geometry": {
 *     "type": "Point",
 *     "coordinates": [110, 40]
 *   }
 * }
 * var geom = turf.getType(point)
 * //="Point"
 */
export function getType(geojson, name) {
    if (!geojson) throw new Error(`${name || 'geojson'  } is required`);
    // GeoJSON Feature & GeometryCollection
    if (geojson.geometry && geojson.geometry.type) return geojson.geometry.type;
    // GeoJSON Geometry & FeatureCollection
    if (geojson.type) return geojson.type;
    throw new Error(`${name || 'geojson'  } is invalid`);
}