#

API Docs for: 3.10.3
Show: Inherited Protected Private Deprecated

# BaseObservable Class

Uses

- AttributeObservable
- EventTarget

Defined in: `base/js/BaseObservable.js:19`
Module: base-observable
Parent Module: base

Available since 3.8.0

Provides an augmentable implementation of lifecycle and attribute events for `BaseCore`.

- Index
- Methods
- Events

## Item Index

### Methods

- _defAttrChangeFn
- _defDestroyFn
- _defInitFn
- _fireAttrChange
- _getFullType
- _getType
- _initAttribute
- _monitor
- _parseType
- _preInitEventCfg
- _publish
- _set
- _setAttrs
- addTarget
- after
- before
- bubble
- destroy
- detach
- detachAll
- fire
- getEvent
- getTargets
- init
- on
- once
- onceAfter
- parseType
- publish
- removeTarget
- set
- setAttrs
- subscribe deprecated
- unsubscribe deprecated
- unsubscribeAll deprecated

### Events

- destroy
- init

## Methods

### `_defAttrChangeFn`

(

- `e`

)
private

Inherited from AttributeObservable: `attribute/js/AttributeObservable.js:186`

Default function for attribute change events.

#### Parameters:

- `e` EventFacade

  The event object for attribute change events.

### `_defDestroyFn`

(

- `e`

)
protected

Defined in `base/js/BaseObservable.js:190`

Default destroy event handler

#### Parameters:

- `e` EventFacade

  Event object

### `_defInitFn`

(

- `e`

)
protected

Defined in `base/js/BaseObservable.js:178`

Default init event handler

#### Parameters:

- `e` EventFacade

  Event object, with a cfg property which refers to the configuration object passed to the constructor.

### `_fireAttrChange`

(

- `attrName`
- `subAttrName`
- `currVal`
- `newVal`
- `opts`
- `[cfg]`

)
private

Inherited from AttributeObservable: `attribute/js/AttributeObservable.js:120`

Utility method to help setup the event payload and fire the attribute change event.

#### Parameters:

- `attrName` String

  The name of the attribute

- `subAttrName` String

  The full path of the property being changed, if this is a sub-attribute value being change. Otherwise null.

- `currVal` Any

  The current value of the attribute

- `newVal` Any

  The new value of the attribute

- `opts` Object

  Any additional event data to mix into the attribute change event's event facade.

- `[cfg]` Object optional

  The attribute config stored in State, if already available.

### `_getFullType`

(

- `type`

)
String private

Inherited from EventTarget: `event-custom/js/event-target.js:586`

Returns the fully qualified type, given a short type string. That is, returns "foo:bar" when given "bar" if "foo" is the configured prefix.

NOTE: This method, unlike _getType, does no checking of the value passed in, and is designed to be used with the low level _publish() method, for critical path implementations which need to fast-track publish for performance reasons.

#### Parameters:

- `type` String

  The short type to prefix

#### Returns:

String: The prefixed type, if a prefix is set, otherwise the type passed in

### `_getType`

() private

Inherited from EventTarget: `event-custom/js/event-target.js:36`

If the instance has a prefix attribute and the event type is not prefixed, the instance prefix is applied to the supplied type.

### `_initAttribute`

() private

Defined in `base/js/BaseObservable.js:36`

Initializes Attribute

### `_monitor`

(

- `what`
- `eventType`
- `o`

)
private

Inherited from EventTarget: `event-custom/js/event-target.js:658`

This is the entry point for the event monitoring system. You can monitor 'attach', 'detach', 'fire', and 'publish'. When configured, these events generate an event. click -> clickattach, clickdetach, click_publish -- these can be subscribed to like other events to monitor the event system. Inividual published events can have monitoring turned on or off (publish can't be turned off before it it published) by setting the events 'monitor' config.

#### Parameters:

- `what` String

  'attach', 'detach', 'fire', or 'publish'

- `eventType` String | CustomEvent

  The prefixed name of the event being monitored, or the CustomEvent object.

- `o` Object

  Information about the event interaction, such as fire() args, subscription category, publish config

### `_parseType`

() private

Inherited from EventTarget: `event-custom/js/event-target.js:52`

Returns an array with the detach key (if provided), and the prefixed event name from _getType Y.on('detachcategory| menu:click', fn)

### `_preInitEventCfg`

(

- `config`

)
private

Defined in `base/js/BaseObservable.js:98`

Handles the special on, after and target properties which allow the user to easily configure on and after listeners as well as bubble targets during construction, prior to init.

#### Parameters:

- `config` Object

  The user configuration object

### `_publish`

(

- `fullType`
- `etOpts`
- `ceOpts`

)
CustomEvent private

Inherited from EventTarget: `event-custom/js/event-target.js:610`

The low level event publish implementation. It expects all the massaging to have been done outside of this method. e.g. the `type` to `fullType` conversion. It's designed to be a fast path publish, which can be used by critical code paths to improve performance.

#### Parameters:

- `fullType` String

  The prefixed type of the event to publish.

- `etOpts` Object

  The EventTarget specific configuration to mix into the published event.

- `ceOpts` Object

  The publish specific configuration to mix into the published event.

#### Returns:

CustomEvent: The published event. If called without `etOpts` or `ceOpts`, this will be the default `CustomEvent` instance, and can be configured independently.

### `_set`

(

- `name`
- `val`
- `opts`

)
Object protected chainable

Inherited from AttributeObservable: `attribute/js/AttributeObservable.js:70`

Allows setting of readOnly/writeOnce attributes. See set for argument details.

#### Parameters:

- `name` String

  The name of the attribute.

- `val` Any

  The value to set the attribute to.

- `opts` Object

  (Optional) Optional event data to be mixed into the event facade passed to subscribers of the attribute's change event.

#### Returns:

Object: A reference to the host object.

### `_setAttrs`

(

- `attrs`
- `opts`

)
Object protected chainable

Inherited from AttributeObservable: `attribute/js/AttributeObservable.js:100`

Implementation behind the public setAttrs method, to set multiple attribute values.

#### Parameters:

- `attrs` Object

  An object with attributes name/value pairs.

- `opts` Object

  Properties to mix into the event payload. These are shared and mixed into each set

#### Returns:

Object: A reference to the host object.

### `addTarget`

(

- `o`

)

Inherited from EventTarget: `event-custom/js/event-facade.js:455`

Registers another EventTarget as a bubble target. Bubble order is determined by the order registered. Multiple targets can be specified.

Events can only bubble if emitFacade is true.

Included in the event-custom-complex submodule.

#### Parameters:

- `o` EventTarget

  the target to add

### `after`

(

- `type`
- `fn`
- `[context]`
- `[arg*]`

)
EventHandle

Inherited from EventTarget: `event-custom/js/event-target.js:833`

Subscribe to a custom event hosted by this object. The supplied callback will execute after any listeners add via the subscribe method, and after the default function, if configured for the event, has executed.

#### Parameters:

- `type` String

  The name of the event

- `fn` Function

  The callback to execute in response to the event

- `[context]` Object optional

  Override `this` object in callback

- `[arg*]` Any optional

  0..n additional arguments to supply to the subscriber

#### Returns:

EventHandle: A subscription handle capable of detaching the subscription

### `before`

()

Inherited from EventTarget: `event-custom/js/event-target.js:870`

Executes the callback before a DOM event, custom event or method. If the first argument is a function, it is assumed the target is a method. For DOM and custom events, this is an alias for Y.on.

For DOM and custom events: type, callback, context, 0-n arguments

For methods: callback, object (method host), methodName, context, 0-n arguments

#### Returns:

detach handle

### `bubble`

(

- `evt`

)
Boolean

Inherited from EventTarget: `event-custom/js/event-facade.js:507`

Propagate an event. Requires the event-custom-complex module.

#### Parameters:

- `evt` CustomEvent

  the custom event to propagate

#### Returns:

Boolean: the aggregated return value from Event.Custom.fire

### `destroy`

() Base chainable

Defined in `base/js/BaseObservable.js:133`

Destroy lifecycle method. Fires the destroy event, prior to invoking destructors for the class hierarchy.

Subscribers to the destroy event can invoke preventDefault on the event object, to prevent destruction from proceeding.

#### Returns:

Base: A reference to this object

### `detach`

(

- `type`
- `fn`
- `context`

)
EventTarget

Inherited from EventTarget: `event-custom/js/event-target.js:346`

Detach one or more listeners the from the specified event

#### Parameters:

- `type` String | Object

  Either the handle to the subscriber or the type of event. If the type is not specified, it will attempt to remove the listener from all hosted events.

- `fn` Function

  The subscribed function to unsubscribe, if not supplied, all subscribers will be removed.

- `context` Object

  The custom object passed to subscribe. This is optional, but if supplied will be used to disambiguate multiple listeners that are the same (e.g., you subscribe many object using a function that lives on the prototype)

#### Returns:

EventTarget: the host

### `detachAll`

(

- `type`

)

Inherited from EventTarget: `event-custom/js/event-target.js:469`

Removes all listeners from the specified event. If the event type is not specified, all listeners from all hosted custom events will be removed.

#### Parameters:

- `type` String

  The type, or name of the event

### `fire`

(

- `type`
- `arguments`

)
EventTarget

Inherited from EventTarget: `event-custom/js/event-target.js:695`

Fire a custom event by name. The callback functions will be executed from the context specified when the event was created, and with the following parameters.

If the custom event object hasn't been created, then the event hasn't been published and it has no subscribers. For performance sake, we immediate exit in this case. This means the event won't bubble, so if the intention is that a bubble target be notified, the event must be published on this object first.

The first argument is the event type, and any additional arguments are passed to the listeners as parameters. If the first of these is an object literal, and the event is configured to emit an event facade, that object is mixed into the event facade and the facade is provided in place of the original object.

#### Parameters:

- `type` String | Object

  The type of the event, or an object that contains a 'type' property.

- `arguments` Object*

  an arbitrary set of parameters to pass to the handler. If the first of these is an object literal and the event is configured to emit an event facade, the event facade will replace that parameter after the properties the object literal contains are copied to the event facade.

#### Returns:

EventTarget: the event host

### `getEvent`

(

- `type`
- `prefixed`

)
CustomEvent

Inherited from EventTarget: `event-custom/js/event-target.js:814`

Returns the custom event of the provided type has been created, a falsy value otherwise

#### Parameters:

- `type` String

  the type, or name of the event

- `prefixed` String

  if true, the type is prefixed already

#### Returns:

CustomEvent: the custom event or null

### `getTargets`

()

Inherited from EventTarget: `event-custom/js/event-facade.js:479`

Returns an array of bubble targets for this object.

#### Returns:

EventTarget[]

### `init`

(

- `config`

)
Base chainable

Defined in `base/js/BaseObservable.js:50`

Init lifecycle method, invoked during construction. Fires the init event prior to setting up attributes and invoking initializers for the class hierarchy.

#### Parameters:

- `config` Object

  Object with configuration property name/value pairs

#### Returns:

Base: A reference to this object

### `on`

(

- `type`
- `fn`
- `[context]`
- `[arg*]`

)
EventHandle

Inherited from EventTarget: `event-custom/js/event-target.js:188`

Subscribe a callback function to a custom event fired by this object or from an object that bubbles its events to this object.

Callback functions for events published with `emitFacade = true` will receive an `EventFacade` as the first argument (typically named "e"). These callbacks can then call `e.preventDefault()` to disable the behavior published to that event's `defaultFn`. See the `EventFacade` API for all available properties and methods. Subscribers to non-`emitFacade` events will receive the arguments passed to `fire()` after the event name.

To subscribe to multiple events at once, pass an object as the first argument, where the key:value pairs correspond to the eventName:callback, or pass an array of event names as the first argument to subscribe to all listed events with the same callback.

Returning `false` from a callback is supported as an alternative to calling `e.preventDefault(); e.stopPropagation();`. However, it is recommended to use the event methods whenever possible.

#### Parameters:

- `type` String

  The name of the event

- `fn` Function

  The callback to execute in response to the event

- `[context]` Object optional

  Override `this` object in callback

- `[arg*]` Any optional

  0..n additional arguments to supply to the subscriber

#### Returns:

EventHandle: A subscription handle capable of detaching that subscription

### `once`

(

- `type`
- `fn`
- `[context]`
- `[arg*]`

)
EventHandle

Inherited from EventTarget: `event-custom/js/event-target.js:124`

Listen to a custom event hosted by this object one time. This is the equivalent to `on` except the listener is immediatelly detached when it is executed.

#### Parameters:

- `type` String

  The name of the event

- `fn` Function

  The callback to execute in response to the event

- `[context]` Object optional

  Override `this` object in callback

- `[arg*]` Any optional

  0..n additional arguments to supply to the subscriber

#### Returns:

EventHandle: A subscription handle capable of detaching the subscription

### `onceAfter`

(

- `type`
- `fn`
- `[context]`
- `[arg*]`

)
EventHandle

Inherited from EventTarget: `event-custom/js/event-target.js:146`

Listen to a custom event hosted by this object one time. This is the equivalent to `after` except the listener is immediatelly detached when it is executed.

#### Parameters:

- `type` String

  The name of the event

- `fn` Function

  The callback to execute in response to the event

- `[context]` Object optional

  Override `this` object in callback

- `[arg*]` Any optional

  0..n additional arguments to supply to the subscriber

#### Returns:

EventHandle: A subscription handle capable of detaching that subscription

### `parseType`

(

- `type`
- `[pre=this._yuievt.config.prefix]`

)
Array

Inherited from EventTarget: `event-custom/js/event-target.js:168`

Available since 3.3.0

Takes the type parameter passed to 'on' and parses out the various pieces that could be included in the type. If the event type is passed without a prefix, it will be expanded to include the prefix one is supplied or the event target is configured with a default prefix.

#### Parameters:

- `type` String

  the type

- `[pre=this._yuievt.config.prefix]` String optional

  the prefix

#### Returns:

Array: an array containing: * the detach category, if supplied, * the prefixed event type, * whether or not this is an after listener, * the supplied event type

### `publish`

(

- `type`
- `opts`

)
CustomEvent

Inherited from EventTarget: `event-custom/js/event-target.js:493`

Creates a new custom event of the specified type. If a custom event by that name already exists, it will not be re-created. In either case the custom event is returned.

#### Parameters:

- `type` String

  the type, or name of the event

- `opts` Object

  optional config params. Valid properties are:

  - 'broadcast': whether or not the YUI instance and YUI global are notified when the event is fired (false)
  - 'bubbles': whether or not this event bubbles (true) Events can only bubble if emitFacade is true.
  - 'context': the default execution context for the listeners (this)
  - 'defaultFn': the default function to execute when this event fires if preventDefault was not called
  - 'emitFacade': whether or not this event emits a facade (false)
  - 'prefix': the prefix for this targets events, e.g., 'menu' in 'menu:click'
  - 'fireOnce': if an event is configured to fire once, new subscribers after the fire will be notified immediately.
  - 'async': fireOnce event listeners will fire synchronously if the event has already fired unless async is true.
  - 'preventable': whether or not preventDefault() has an effect (true)
  - 'preventedFn': a function that is executed when preventDefault is called
  - 'queuable': whether or not this event can be queued during bubbling (false)
  - 'silent': if silent is true, debug messages are not provided for this event.
  - 'stoppedFn': a function that is executed when stopPropagation is called

  - 'monitored': specifies whether or not this event should send notifications about when the event has been attached, detached, or published.
  - 'type': the event type (valid option if not provided as the first parameter to publish)

#### Returns:

CustomEvent: the custom event

### `removeTarget`

(

- `o`

)

Inherited from EventTarget: `event-custom/js/event-facade.js:489`

Removes a bubble target

#### Parameters:

- `o` EventTarget

  the target to remove

### `set`

(

- `name`
- `value`
- `opts`

)
Object chainable

Inherited from AttributeObservable: `attribute/js/AttributeObservable.js:46`

Sets the value of an attribute.

#### Parameters:

- `name` String

  The name of the attribute. If the current value of the attribute is an Object, dot notation can be used to set the value of a property within the object (e.g. `set("x.y.z", 5)`).

- `value` Any

  The value to set the attribute to.

- `opts` Object

  (Optional) Optional event data to be mixed into the event facade passed to subscribers of the attribute's change event. This can be used as a flexible way to identify the source of a call to set, allowing the developer to distinguish between set called internally by the host, vs. set called externally by the application developer.

#### Returns:

Object: A reference to the host object.

### `setAttrs`

(

- `attrs`
- `opts`

)
Object chainable

Inherited from AttributeObservable: `attribute/js/AttributeObservable.js:87`

Sets multiple attribute values.

#### Parameters:

- `attrs` Object

  An object with attributes name/value pairs.

- `opts` Object

  Properties to mix into the event payload. These are shared and mixed into each set

#### Returns:

Object: A reference to the host object.

### `subscribe`

() deprecated

Inherited from EventTarget: `event-custom/js/event-target.js:336`

Deprecated: use on

subscribe to an event

### `unsubscribe`

() deprecated

Inherited from EventTarget: `event-custom/js/event-target.js:459`

Deprecated: use detach

detach a listener

### `unsubscribeAll`

(

- `type`

)
deprecated

Inherited from EventTarget: `event-custom/js/event-target.js:480`

Deprecated: use detachAll

Removes all listeners from the specified event. If the event type is not specified, all listeners from all hosted custom events will be removed.

#### Parameters:

- `type` String

  The type, or name of the event

## Events

### `destroy`

Defined in `base/js/BaseObservable.js:151`

Lifecycle event for the destroy phase, fired prior to destruction. Invoking the preventDefault method on the event object provided to subscribers will prevent destruction from proceeding.

Subscribers to the "after" moment of this event, will be notified after destruction is complete (and as a result cannot prevent destruction).

#### Event Payload:

- `e` EventFacade

  Event object

### `init`

Defined in `base/js/BaseObservable.js:62`

Lifecycle event for the init phase, fired prior to initialization. Invoking the preventDefault() method on the event object provided to subscribers will prevent initialization from occuring.

Subscribers to the "after" momemt of this event, will be notified after initialization of the object is complete (and therefore cannot prevent initialization).

#### Event Payload:

- `e` EventFacade

  Event object, with a cfg property which refers to the configuration object passed to the constructor.