tmp-demo-frontend/node_modules/leaflet/src/layer/FeatureGroup.js

import {LayerGroup} from './LayerGroup';
import {LatLngBounds} from '../geo/LatLngBounds';

/*
 * @class FeatureGroup
 * @aka L.FeatureGroup
 * @inherits LayerGroup
 *
 * Extended `LayerGroup` that makes it easier to do the same thing to all its member layers:
 *  * [`bindPopup`](#layer-bindpopup) binds a popup to all of the layers at once (likewise with [`bindTooltip`](#layer-bindtooltip))
 *  * Events are propagated to the `FeatureGroup`, so if the group has an event
 * handler, it will handle events from any of the layers. This includes mouse events
 * and custom events.
 *  * Has `layeradd` and `layerremove` events
 *
 * @example
 *
 * ```js
 * L.featureGroup([marker1, marker2, polyline])
 * 	.bindPopup('Hello world!')
 * 	.on('click', function() { alert('Clicked on a member of the group!'); })
 * 	.addTo(map);
 * ```
 */

export var FeatureGroup = LayerGroup.extend({

	addLayer: function (layer) {
		if (this.hasLayer(layer)) {
			return this;
		}

		layer.addEventParent(this);

		LayerGroup.prototype.addLayer.call(this, layer);

		// @event layeradd: LayerEvent
		// Fired when a layer is added to this `FeatureGroup`
		return this.fire('layeradd', {layer: layer});
	},

	removeLayer: function (layer) {
		if (!this.hasLayer(layer)) {
			return this;
		}
		if (layer in this._layers) {
			layer = this._layers[layer];
		}

		layer.removeEventParent(this);

		LayerGroup.prototype.removeLayer.call(this, layer);

		// @event layerremove: LayerEvent
		// Fired when a layer is removed from this `FeatureGroup`
		return this.fire('layerremove', {layer: layer});
	},

	// @method setStyle(style: Path options): this
	// Sets the given path options to each layer of the group that has a `setStyle` method.
	setStyle: function (style) {
		return this.invoke('setStyle', style);
	},

	// @method bringToFront(): this
	// Brings the layer group to the top of all other layers
	bringToFront: function () {
		return this.invoke('bringToFront');
	},

	// @method bringToBack(): this
	// Brings the layer group to the back of all other layers
	bringToBack: function () {
		return this.invoke('bringToBack');
	},

	// @method getBounds(): LatLngBounds
	// Returns the LatLngBounds of the Feature Group (created from bounds and coordinates of its children).
	getBounds: function () {
		var bounds = new LatLngBounds();

		for (var id in this._layers) {
			var layer = this._layers[id];
			bounds.extend(layer.getBounds ? layer.getBounds() : layer.getLatLng());
		}
		return bounds;
	}
});

// @factory L.featureGroup(layers?: Layer[], options?: Object)
// Create a feature group, optionally given an initial set of layers and an `options` object.
export var featureGroup = function (layers, options) {
	return new FeatureGroup(layers, options);
};