# Yahoo! UI Library

### event-custom 3.0.0b1

Yahoo! UI Library > event-custom > CustomEvent
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## Class CustomEvent

The CustomEvent class lets you define events for your application that can be subscribed to by one or more independent component.

### Constructor

CustomEvent `( type , o )`

Parameters:
  `type <String>` The type of event, which is passed to the callback when the event fires
  `o <object>` configuration object

### Properties

#### afters - `Subscriber{}`

'After' subscribers

#### broadcast - `int`

If 0, this event does not broadcast. If 1, the YUI instance is notified every time this event fires. If 2, the YUI instance and the YUI global (if event is enabled on the global) are notified every time this event fires.

#### bubbles - `boolean`

Specifies whether or not a subscriber can stop the event propagation via stopPropagation(), stopImmediatePropagation(), or halt()
Default Value: true

#### context - `object`

The context the the event will fire from by default. Defaults to the YUI instance.

#### defaultFn - `Function`

The default function to execute after event listeners have fire, but only if the default action was not prevented.

#### emitFacade - `boolean`

If set to true, the custom event will deliver an EventFacade object that is similar to a DOM event object.
Default Value: false

#### fired - `boolean`

This event has fired if true
Default Value: false;

#### fireOnce - `boolean`

This event should only fire one time if true, and if it has fired, any new subscribers should be notified immediately.
Default Value: false;

#### host - `EventTarget`

Specifies the host for this custom event. This is used to enable event bubbling

#### preventable - `boolean`

Specifies whether or not this event's default function can be cancelled by a subscriber by executing preventDefault() on the event facade
Default Value: true

#### prevented - `int`

Flag for preventDefault that is modified during fire(). if it is not 0, the default behavior for this event

#### preventedFn - `Function`

The function to execute if a subscriber calls preventDefault

#### signature - `int`

Supports multiple options for listener signatures in order to port YUI 2 apps.
Default Value: 9

#### silent - `boolean`

By default all custom events are logged in the debug build, set silent to true to disable debug outpu for this event.

#### stopped - `int`

Flag for stopPropagation that is modified during fire() 1 means to stop propagation to bubble targets. 2 means to also stop additional subscribers on this target.

#### stoppedFn - `Function`

The function to execute if a subscriber calls stopPropagation or stopImmediatePropagation

#### subscribers - `Subscriber{}`

The subscribers to this event

#### type - `string`

The type of event, returned to subscribers when the event fires

### Methods

#### _delete

`private void _delete ( subscriber )`

Parameters:
  `subscriber <object>` object

Returns: `void`

#### _notify

`private void _notify ( s , args )`
Notify a single subscriber

Parameters:
  `s <Subscriber>` the subscriber
  `args <Array>` the arguments array to apply to the listener

Returns: `void`

#### after

`EventHandle|EventTarget after ( fn )`
Listen for this event after the normal subscribers have been notified and the default behavior has been applied. If a normal subscriber prevents the default behavior, it also prevents after listeners from firing.

Parameters:
  `fn <Function>` The function to execute

Returns: `EventHandle|EventTarget`
  unsubscribe handle or a chainable event target depending on the 'chain' config.

#### applyConfig

`void applyConfig ( o , force )`
Apply configuration properties. Only applies the CONFIG whitelist

Parameters:
  `o <object>` hash of properties to apply
  `force <boolean>` if true, properties that exist on the event will be overwritten.

Returns: `void`

#### detach

`boolean|EventTarget detach ( fn , context )`
Detach listeners.

Parameters:
  `fn <Function>` The subscribed function to remove, if not supplied all will be removed
  `context <Object>` The context object passed to subscribe.

Returns: `boolean|EventTarget`
  returns a chainable event target or a boolean for legacy detach support.

#### detachAll

`int detachAll ( )`
Removes all listeners

Returns: `int`
  The number of listeners unsubscribed

#### fire

`boolean fire ( arguments )`
Notifies the subscribers. The callback functions will be executed from the context specified when the event was created, and with the following parameters:

- The type of event
- All of the arguments fire() was executed with as an array
- The custom object (if any) that was passed into the subscribe() method

Parameters:
  `arguments <Object*>` an arbitrary set of parameters to pass to the handler.

Returns: `boolean`
  false if one of the subscribers returned false, true otherwise

#### halt

`void halt ( immediate )`
Stops the event propagation and prevents the default event behavior.

Parameters:
  `immediate <boolean>` if true additional listeners on the current target will not be executed

Returns: `void`

#### log

`void log ( msg , cat )`
Logger abstraction to centralize the application of the silent flag

Parameters:
  `msg <string>` message to log
  `cat <string>` log category

Returns: `void`

#### on

`EventHandle|EventTarget on ( fn )`
Listen for this event

Parameters:
  `fn <Function>` The function to execute

Returns: `EventHandle|EventTarget`
  unsubscribe handle or a chainable event target depending on the 'chain' config.

#### preventDefault

`void preventDefault ( )`
Prevents the execution of this event's defaultFn

Returns: `void`

#### stopImmediatePropagation

`void stopImmediatePropagation ( )`
Stops propagation to bubble targets, and prevents any remaining subscribers on the current target from executing.

Returns: `void`

#### stopPropagation

`void stopPropagation ( )`
Stop propagation to bubble targets

Returns: `void`

#### subscribe

`EventHandle|EventTarget subscribe ( fn )`
Listen for this event

Parameters:
  `fn <Function>` The function to execute

Returns: `EventHandle|EventTarget`
  unsubscribe handle or a chainable event target depending on the 'chain' config.

Deprecated use on

#### toString

`void toString ( )`

Returns: `void`

#### unsubscribe

`boolean|EventTarget unsubscribe ( fn , context )`
Detach listeners.

Parameters:
  `fn <Function>` The subscribed function to remove, if not supplied all will be removed
  `context <Object>` The context object passed to subscribe.

Returns: `boolean|EventTarget`
  returns a chainable event target or a boolean for legacy detach support.

Deprecated use detach

#### unsubscribeAll

`int unsubscribeAll ( )`
Removes all listeners

Returns: `int`
  The number of listeners unsubscribed

Deprecated use detachAll

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