Leaflet Identify function (similar to ESRI ArcGIS Javascript API function) for finding polygons based on a given latlng from in a L.GeoJson feature layer group.Requires Leaflet and geojson-js-utils: https://github.com/maxogden/geojson-js-utils

leaflet-geojson-identify.js

L.GeoJSON.include({
  identify: function(latlng) {
    var features = new L.FeatureGroup(),
      geopoint = {
        type: 'Point',
        coordinates: [latlng.lng, latlng.lat]
      };
    this.eachLayer(function (layer) {
      if (gju.pointInPolygon(geopoint, layer.feature.geometry)) {
        features.addLayer(layer);
      }
    });
    return features;
  }
});

You could have written L.GeoJSON.include({...}) :)