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

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

turf.propEach(features, function (currentProperties, featureIndex) {
  //=currentProperties
  //=featureIndex
});