OpenLayers

Class: Observable

ol.Observable 


import Observable from 'ol/observable';

Abstract base class; normally only used for creating subclasses and not instantiated in apps. An event target providing convenient methods for listener registration and unregistration. A generic change event is always available through ol.Observable#changed.

new ol.Observable()

src/ol/observable.js, line 23
Fires:

Subclasses

Extends

Methods

ol.Observable.unByKey(key)

src/ol/observable.js, line 43

Removes an event listener using the key returned by on() or once().

Name Type Description
key ol.EventsKey | Array.<ol.EventsKey>

The key returned by on() or once() (or an array of keys).

changed()

src/ol/observable.js, line 58

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

dispatchEvent(event)

src/ol/observable.js, line 75

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 Object | ol.events.Event | string

Event object.

getRevision(){number}

src/ol/observable.js, line 84

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

Returns:
Revision.

on(type, listener, opt_this){ol.EventsKey|Array.<ol.EventsKey>}

src/ol/observable.js, line 99

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.
this Object

The object to use as this in listener.
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, opt_this){ol.EventsKey|Array.<ol.EventsKey>}

src/ol/observable.js, line 124

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.
this Object

The object to use as this in listener.
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.

un(type, listener, opt_this)

src/ol/observable.js, line 147

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.
this Object

The object which was used as this by the listener.