Version 3.16.0
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EventTarget Class

EventTarget provides the implementation for any object to publish, subscribe and fire to custom events, and also alows other EventTargets to target the object with events sourced from the other object. EventTarget is designed to be used with Y.augment to wrap EventCustom in an interface that allows events to be listened to and fired by name. This makes it possible for implementing code to subscribe to an event that either has not been created yet, or will not be created at all.

Methods

_getFullType

(
  • type
)
String private

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

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

_hasPotentialSubscribers

(
  • fullType
)
Boolean private

Provided by the event-custom-complex module.

Defined in event-custom/js/event-facade.js:643

Parameters:

  • fullType String

    The fully prefixed type name

Returns:

Boolean: Whether the event has potential subscribers or not

_monitor

(
  • what
  • eventType
  • o
)
private

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

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

_publish

(
  • fullType
  • etOpts
  • ceOpts
)
CustomEvent private

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.

addTarget

(
  • o
)
chainable

Provided by the event-custom-complex module.

Defined in event-custom/js/event-facade.js:496

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:

after

(
  • type
  • fn
  • [context]
  • [arg*]
)
EventHandle

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

()

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

Provided by the event-custom-complex module.

Defined in event-custom/js/event-facade.js:554

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

Parameters:

Returns:

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

detach

(
  • type
  • fn
  • context
)
EventTarget

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
)

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
)
Boolean

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.

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.

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.

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:

Boolean: True if the whole lifecycle of the event went through, false if at any point the event propagation was halted.

getEvent

(
  • type
  • prefixed
)
CustomEvent

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

()

Provided by the event-custom-complex module.

Defined in event-custom/js/event-facade.js:523

Returns an array of bubble targets for this object.

Returns:

EventTarget[]

on

(
  • type
  • fn
  • [context]
  • [arg*]
)
EventHandle

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

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

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]
)
Array

Defined in 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] String optional

    The prefix. Defaults to this._yuievt.config.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

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
)
chainable

Provided by the event-custom-complex module.

Defined in event-custom/js/event-facade.js:533

Removes a bubble target

Parameters:

subscribe

() deprecated

Defined in event-custom/js/event-target.js:336

Deprecated: use on

subscribe to an event

unsubscribe

() deprecated

Defined in event-custom/js/event-target.js:459

Deprecated: use detach

detach a listener

unsubscribeAll

(
  • type
)
deprecated

Defined in 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