# Class: LayerGroup

This documentation is for OpenLayers v10.9.0. The latest is v.

## ol/layer/Group~LayerGroup

    import LayerGroup from 'ol/layer/Group.js';

A `Collection` of layers that are handled together.

A generic `change` event is triggered when the group/Collection changes.

#### new LayerGroup(options)

layer/Group.js, line 105

  Name | Type | Description
  --- | --- | ---
  `opacity` | number (defaults to 1) | Opacity (0, 1).
  `visible` | boolean (defaults to true) | Visibility.
  `extent` | Extent | undefined | The bounding extent for layer rendering. The layer will not be rendered outside of this extent.
  `zIndex` | number | undefined | The z-index for layer rendering. At rendering time, the layers will be ordered, first by Z-index and then by position. When `undefined`, a `zIndex` of 0 is assumed for layers that are added to the map's `layers` collection, or `Infinity` when the layer's `setMap()` method was used.
  `minResolution` | number | undefined | The minimum resolution (inclusive) at which this layer will be visible.
  `maxResolution` | number | undefined | The maximum resolution (exclusive) below which this layer will be visible.
  `minZoom` | number | undefined | The minimum view zoom level (exclusive) above which this layer will be visible.
  `maxZoom` | number | undefined | The maximum view zoom level (inclusive) at which this layer will be visible.
  `layers` | Array<BaseLayer> | Collection<BaseLayer> | undefined | Child layers.
  `properties` | Object.<string, *> | undefined | Arbitrary observable properties. Can be accessed with `#get()` and `#set()`.

  ##### Fires:

  - `addlayer` (GroupEvent) - Triggered when a layer is added
  - `change` (BaseEvent) - Generic change event. Triggered when the revision counter is increased.
  - `change:extent` (ObjectEvent)
  - `change:layers` (ObjectEvent)
  - `change:maxResolution` (ObjectEvent)
  - `change:maxZoom` (ObjectEvent)
  - `change:minResolution` (ObjectEvent)
  - `change:minZoom` (ObjectEvent)
  - `change:opacity` (ObjectEvent)
  - `change:visible` (ObjectEvent)
  - `change:zIndex` (ObjectEvent)
  - `error` (BaseEvent) - Generic error event. Triggered when an error occurs.
  - `propertychange` (ObjectEvent) - Triggered when a property is changed.
  - `removelayer` (GroupEvent) - Triggered when a layer is removed

### Extends

- BaseLayer

### Observable Properties

Name | Type | Settable | ObjectEvent type | Description
--- | --- | --- | --- | ---
`extent` | Extent | undefined | yes | `change:extent` | The layer extent.
`layers` | Collection<BaseLayer> | yes | `change:layers` | Collection of `layers` that are part of this group.
`maxResolution` | number | yes | `change:maxresolution` | The maximum resolution of the layer.
`maxZoom` | number | yes | `change:maxzoom` | The maximum zoom level of the layer.
`minResolution` | number | yes | `change:minresolution` | The minimum resolution of the layer.
`minZoom` | number | yes | `change:minzoom` | The minimum zoom level of the layer.
`opacity` | number | yes | `change:opacity` | The opacity of the layer.
`visible` | boolean | yes | `change:visible` | The value of the `visible` property of the layer.
`zIndex` | number | undefined | yes | `change:zindex` | The Z-index of the layer.

### Methods

#### changed() inherited

Observable.js, line 68

  Increases the revision counter and dispatches a 'change' event.

#### dispatchEvent(event){boolean | undefined} inherited

events/Target.js, line 85

  Dispatches an event and calls all listeners listening for events of this type. The event parameter can either be a string or an Object with a `type` property.

  Name | Type | Description
  --- | --- | ---
  `event` | BaseEvent | string | Event object.

  ##### Returns:

  `false` if anyone called preventDefault on the event object or if any of the listeners returned false.

#### get(key){*} inherited

Object.js, line 136

  Gets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.

  ##### Returns:

  Value.

#### getExtent(){Extent | undefined} inherited

layer/Base.js, line 210

  Return the `extent` of the layer or `undefined` if it will be visible regardless of extent.

  ##### Returns:

  The layer extent.

#### getKeys(){Array.<string>} inherited

Object.js, line 149

  Get a list of object property names.

  ##### Returns:

  List of property names.

#### getLayers(){Collection<BaseLayer>}

layer/Group.js, line 277

  Returns the `collection` of `layers` in this group.

  ##### Returns:

  Collection of `layers` that are part of this group.

#### getMaxResolution(){number} inherited

layer/Base.js, line 223

  Return the maximum resolution of the layer. Returns Infinity if the layer has no maximum resolution set.

  ##### Returns:

  The maximum resolution of the layer.

#### getMaxZoom(){number} inherited

layer/Base.js, line 256

  Return the maximum zoom level of the layer. Returns Infinity if the layer has no maximum zoom set.

  ##### Returns:

  The maximum zoom level of the layer.

#### getMinResolution(){number} inherited

layer/Base.js, line 234

  Return the minimum resolution of the layer. Returns 0 if the layer has no minimum resolution set.

  ##### Returns:

  The minimum resolution of the layer.

#### getMinZoom(){number} inherited

layer/Base.js, line 245

  Return the minimum zoom level of the layer. Returns -Infinity if the layer has no minimum zoom set.

  ##### Returns:

  The minimum zoom level of the layer.

#### getOpacity(){number} inherited

layer/Base.js, line 266

  Return the opacity of the layer (between 0 and 1).

  ##### Returns:

  The opacity of the layer.

#### getProperties(){NoInfer.<Properties>} inherited

Object.js, line 158

  Get an object of all property names and values.

  ##### Returns:

  Object.

#### getRevision(){number} inherited

Observable.js, line 79

  Get the version number for this object. Each time the object is modified, its version number will be incremented.

  ##### Returns:

  Revision.

#### getVisible(){boolean} inherited

layer/Base.js, line 285

  Return the value of this layer's `visible` property. To find out whether the layer is visible on a map, use `isVisible()` instead.

  ##### Returns:

  The value of the `visible` property of the layer.

#### getZIndex(){number | undefined} inherited

layer/Base.js, line 296

  Return the Z-index of the layer, which is used to order layers before rendering. Returns undefined if the layer is unmanaged.

  ##### Returns:

  The Z-index of the layer.

#### on(type, listener){EventsKey | Array<EventsKey>} inherited

Observable.js, line 152

  Listen for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

  ##### Returns:

  Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

#### once(type, listener){EventsKey | Array<EventsKey>} inherited

Observable.js, line 164

  Listen once for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

  ##### Returns:

  Unique key for the listener. If called with an array of event types as the first argument, the return will be an array of keys.

#### set(key, value, silent) inherited

Object.js, line 218

  Sets a value.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.
  `value` | * | Value.
  `silent` | boolean | undefined | Update without triggering an event.

#### setExtent(extent) inherited

layer/Base.js, line 316

  Set the extent at which the layer is visible. If `undefined`, the layer will be visible at all extents.

  Name | Type | Description
  --- | --- | ---
  `extent` | Extent | undefined | The extent of the layer.

#### setLayers(layers)

layer/Group.js, line 291

  Set the `collection` of `layers` in this group.

  Name | Type | Description
  --- | --- | ---
  `layers` | Collection<BaseLayer> | Collection of `layers` that are part of this group.

#### setMaxResolution(maxResolution) inherited

layer/Base.js, line 326

  Set the maximum resolution at which the layer is visible.

  Name | Type | Description
  --- | --- | ---
  `maxResolution` | number | The maximum resolution of the layer.

#### setMaxZoom(maxZoom) inherited

layer/Base.js, line 348

  Set the maximum zoom (exclusive) at which the layer is visible. Note that the zoom levels for layer visibility are based on the view zoom level, which may be different from a tile source zoom level.

  Name | Type | Description
  --- | --- | ---
  `maxZoom` | number | The maximum zoom of the layer.

#### setMinResolution(minResolution) inherited

layer/Base.js, line 336

  Set the minimum resolution at which the layer is visible.

  Name | Type | Description
  --- | --- | ---
  `minResolution` | number | The minimum resolution of the layer.

#### setMinZoom(minZoom) inherited

layer/Base.js, line 360

  Set the minimum zoom (inclusive) at which the layer is visible. Note that the zoom levels for layer visibility are based on the view zoom level, which may be different from a tile source zoom level.

  Name | Type | Description
  --- | --- | ---
  `minZoom` | number | The minimum zoom of the layer.

#### setOpacity(opacity) inherited

layer/Base.js, line 370

  Set the opacity of the layer, allowed values range from 0 to 1.

  Name | Type | Description
  --- | --- | ---
  `opacity` | number | The opacity of the layer.

#### setProperties(values, silent) inherited

Object.js, line 238

  Sets a collection of key-value pairs. Note that this changes any existing properties and adds new ones (it does not remove any existing properties).

  Name | Type | Description
  --- | --- | ---
  `values` | Partial.<NoInfer.<Properties>> | Values.
  `silent` | boolean | undefined | Update without triggering an event.

#### setVisible(visible) inherited

layer/Base.js, line 381

  Set the visibility of the layer (`true` or `false`).

  Name | Type | Description
  --- | --- | ---
  `visible` | boolean | The visibility of the layer.

#### setZIndex(zindex) inherited

layer/Base.js, line 392

  Set Z-index of the layer, which is used to order layers before rendering. The default Z-index is 0.

  Name | Type | Description
  --- | --- | ---
  `zindex` | number | The z-index of the layer.

#### un(type, listener) inherited

Observable.js, line 173

  Unlisten for a certain type of event.

  Name | Type | Description
  --- | --- | ---
  `type` | string | Array.<string> | The event type or array of event types.
  `listener` | function | The listener function.

#### unset(key, silent) inherited

Object.js, line 262

  Unsets a property.

  Name | Type | Description
  --- | --- | ---
  `key` | string | Key name.
  `silent` | boolean | undefined | Unset without triggering an event.