OpenLayers

Class: Observable

ol/Observable~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 module:ol/Observable~Observable#changed.

new Observable()

Observable.js, line 19
Fires:

Methods

changed()

Observable.js, line 36

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

getRevision(){number}

Observable.js, line 47

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

Returns:
Revision.

on(type, listener){module:ol/events~EventsKey|Array.<module:ol/events~EventsKey>}

Observable.js, line 60

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){module:ol/events~EventsKey|Array.<module:ol/events~EventsKey>}

Observable.js, line 82

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.

un(type, listener)

Observable.js, line 101

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.