OpenLayers 3 API Documentation

Class: Object

ol.Object

Abstract base class; normally only used for creating subclasses and not instantiated in apps. Most non-trivial classes inherit from this.

This extends ol.Observable with observable properties, where each property is observable as well as the object as a whole.

Classes that inherit from this have pre-defined properties, to which you can add your own. The pre-defined properties are listed in this documentation as 'Observable Properties', and have their own accessors; for example, ol.Map has a target property, accessed with getTarget() and changed with setTarget(). Not all properties are however settable. There are also general-purpose accessors get() and set(). For example, get('target') is equivalent to getTarget().

The set accessors trigger a change event, and you can monitor this by registering a listener. For example, ol.View has a center property, so view.on('change:center', function(evt) {...}); would call the function whenever the value of the center property changes. Within the function, evt.target would be the view, so evt.target.getCenter() would return the new center.

You can add your own observable properties with object.set('prop', 'value'), and retrieve that with object.get('prop'). You can listen for changes on that property value with object.on('change:prop', listener). You can get a list of all properties with object.getProperties().

Note that the observable properties are separate from standard JS properties. You can, for example, give your map object a title with map.title='New title' and with map.set('title', 'Another title'). The first will be a hasOwnProperty; the second will appear in getProperties(). Only the second is observable.

The observable properties also implement a form of Key Value Observing. Two objects can be bound together such that a change in one will automatically be reflected in the other. See bindTo method for more details, and see ol.dom.Input for the specific case of binding an object with an HTML element.

new ol.Object(opt_values) experimental

src/ol/object.js, line 172
Name Type Description
values Object.<string, *>

An object with key-value pairs.
Fires:

Subclasses

Extends

Methods

bindTo(key, target, opt_targetKey){ol.ObjectAccessor} experimental

src/ol/object.js, line 326

The bindTo method allows you to set up a two-way binding between a source and target object. The method returns an object with a transform method that you can use to provide from and to functions to transform values on the way from the source to the target and on the way back.

For example, if you had two map views (sourceView and targetView) and you wanted the target view to have double the resolution of the source view, you could transform the resolution on the way to and from the target with the following:

sourceView.bindTo('resolution', targetView)
  .transform(
    function(sourceResolution) {
      // from sourceView.resolution to targetView.resolution
      return 2 * sourceResolution;
    },
    function(targetResolution) {
      // from targetView.resolution to sourceView.resolution
      return targetResolution / 2;
    }
  );
Name Type Description
key string

Key name.
target ol.Object

Target.
targetKey string

Target key.

changed() inherited experimental

src/ol/observable.js, line 52

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

Fires:
  • change experimental

get(key){*} experimental

src/ol/object.js, line 354

Gets a value.

Name Type Description
key string

Key name.
Returns:
Value.

getKeys(){Array.<string>} experimental

src/ol/object.js, line 373

Get a list of object property names.

Returns:
List of property names.

getProperties(){Object.<string, *>} experimental

src/ol/object.js, line 405

Get an object of all property names and values.

Returns:
Object.

getRevision(){number} inherited experimental

src/ol/observable.js, line 62
Returns:
Revision.

on(type, listener, opt_this){goog.events.Key} inherited

src/ol/observable.js, line 75

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.

once(type, listener, opt_this){goog.events.Key} inherited

src/ol/observable.js, line 88

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.

set(key, value) experimental

src/ol/object.js, line 437

Sets a value.

Name Type Description
key string

Key name.
value *

Value.

setProperties(values) experimental

src/ol/object.js, line 456

Sets a collection of key-value pairs.

Name Type Description
values Object.<string, *>

Values.

un(type, listener, opt_this) inherited

src/ol/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.
this Object

The object which was used as this by the listener.

unbind(key) experimental

src/ol/object.js, line 470

Removes a binding. Unbinding will set the unbound property to the current value. The object will not be notified, as the value has not changed.

Name Type Description
key string

Key name.

unbindAll() experimental

src/ol/object.js, line 487

Removes all bindings.

unByKey(key) inherited

src/ol/observable.js, line 114

Removes an event listener using the key returned by on() or once(). Note that using the ol.Observable.unByKey static function is to be preferred.

Name Type Description
key goog.events.Key

The key returned by on() or once().