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 23
Fires:

Subclasses

Extends

Methods

changed()

Observable.js, line 59

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

dispatchEvent(event)

Observable.js, line 76

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 | module:ol/events/Event~Event | string

Event object.

getRevision(){number}

Observable.js, line 85

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 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.

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 122

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 142

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.