Pick the property values from an existing GeoJSON, output as json string

geojson-filter.js

let features = sourceJSON.features,
	newFeatures = [];

features.map((feature, index) => {

	let properties = feature.properties,
		ft = {
			geometry: feature.geometry,
			properties: {
				continent: properties.continent,
				iso_code: properties.iso_a2,
				name: properties.name
			},
			type: feature.type
		};

	newFeatures.push(ft);

	return;
})

let geojson = { type: "FeatureCollection", features: newFeatures };

console.log(JSON.stringify(geojson));