function featureEach(geojson, callback) {
  if (geojson.type === "Feature") {
    callback(geojson, 0);
  } else if (geojson.type === "FeatureCollection") {
    for (var i = 0; i < geojson.features.length; i++) {
      if (callback(geojson.features[i], i) === false) break;
    }
  }
}
Iterate over features in any GeoJSON object, similar to
Array.forEach.

@name featureEach
@param {FeatureCollection|Feature|Geometry} geojson any GeoJSON object
@param {Function} callback a method that takes (currentFeature, featureIndex)
@returns {void}
@example
var features = turf.featureCollection([
  turf.point([26, 37], {foo: 'bar'}),
  turf.point([36, 53], {hello: 'world'})
]);

turf.featureEach(features, function (currentFeature, featureIndex) {
  //=currentFeature
  //=featureIndex
});