events.EventTarget Extends goog.Disposable
Inherit from this class to give your object the ability to dispatch events. Note that this class provides event sending behaviour, not event receiving behaviour: your object will be able to broadcast events, and other objects will be able to listen for those events using goog.events.listen().

The name "EventTarget" reflects the fact that this class implements the EventTarget interface as defined by W3C DOM 2/3, with a few differences:

  • Event objects do not have to implement the Event interface. An object is treated as an event object if it has a 'type' property.
  • You can use a plain string instead of an event object; an event-like object will be created with the 'type' set to the string value.

Unless propagation is stopped, an event dispatched by an EventTarget will bubble to the parent returned by getParentEventTarget. To set the parent, call setParentEventTarget or override getParentEventTarget in a subclass. Subclasses that don't support changing the parent should override the setter to throw an error.

Example usage: 

var source = new goog.events.EventTarget();
function handleEvent(event) {
alert('Type: ' + e.type + '\nTarget: ' + e.target);
}
goog.events.listen(source, 'foo', handleEvent);
...
source.dispatchEvent({type: 'foo'}); // will call handleEvent
// or source.dispatchEvent('foo');
...
goog.events.unlisten(source, 'foo', handleEvent);

// You can also use the Listener interface:
var listener = {
handleEvent: function(event) {
...
}
};
goog.events.listen(source, 'bar', listener);

Inheritance

Constructor

goog.events.EventTarget()

Instance Methods

Public Protected Private
Defined in goog.events.EventTarget
addEventListener(type, handler, opt_capture, opt_handlerScope)
Adds an event listener to the event target. The same handler can only be added once per the type. Even if you add the same handler multiple times using the same type then it will only be called once when the event is dispatched. Supported for legacy but use goog.events.listen(src, type, handler) instead.
Arguments:
type :
string
The type of the event to listen for.
handler :
(Object | null)
The function to handle the event. The handler can also be an object that implements the handleEvent method which takes the event object as argument.
opt_capture :
(boolean | undefined)
In DOM-compliant browsers, this determines whether the listener is fired during the capture or bubble phase of the event.
opt_handlerScope :
(Object | null | undefined)
Object in whose scope to call the listener.
code »
dispatchEvent(e) ⇒
boolean
Dispatches an event (or event like object) and calls all listeners listening for events of this type. The type of the event is decided by the type property on the event object. If any of the listeners returns false OR calls preventDefault then this function will return false. If one of the capture listeners calls stopPropagation, then the bubble listeners won't fire.
Arguments:
e :
(Object | goog.events.Event | null | string)
Event object.
Returns: 
boolean
  If anyone called preventDefault on the event object (or if any of the handlers returns false this will also return false.
code »
disposeInternal()
Unattach listeners from this object. Classes that extend EventTarget may need to override this method in order to remove references to DOM Elements and additional listeners, it should be something like this: 
MyClass.prototype.disposeInternal = function() {
MyClass.superClass_.disposeInternal.call(this);
// Dispose logic for MyClass
};
code »
getParentEventTarget() ⇒
(goog.events.EventTarget | null)
Returns the parent of this event target to use for bubbling.
Returns: 
(goog.events.EventTarget | null)
  The parent EventTarget or null if there is no parent.
code »
removeEventListener(type, handler, opt_capture, opt_handlerScope)
Removes an event listener from the event target. The handler must be the same object as the one added. If the handler has not been added then nothing is done.
Arguments:
type :
string
The type of the event to listen for.
handler :
(Object | null)
The function to handle the event. The handler can also be an object that implements the handleEvent method which takes the event object as argument.
opt_capture :
(boolean | undefined)
In DOM-compliant browsers, this determines whether the listener is fired during the capture or bubble phase of the event.
opt_handlerScope :
(Object | null | undefined)
Object in whose scope to call the listener.
code »
setParentEventTarget(parent)
Sets the parent of this event target to use for bubbling.
Arguments:
parent :
(goog.events.EventTarget | null)
Parent EventTarget (null if none).
code »
Defined in goog.Disposable
dispose() ⇒
undefined
Disposes of the object. If the object hasn't already been disposed of, calls #disposeInternal. Classes that extend goog.Disposable should override #disposeInternal in order to delete references to COM objects, DOM nodes, and other disposable objects. Reentrant.
Returns: 
undefined
  Nothing.
code »
disposeInternal()
Deletes or nulls out any references to COM objects, DOM nodes, or other disposable objects. Classes that extend goog.Disposable should override this method. Not reentrant. To avoid calling it twice, it must only be called from the subclass' disposeInternal method. Everywhere else the public dispose method must be used. For example: 
mypackage.MyClass = function() {
goog.base(this);
// Constructor logic specific to MyClass.
...
};
goog.inherits(mypackage.MyClass, goog.Disposable);

mypackage.MyClass.prototype.disposeInternal = function() {
goog.base(this, 'disposeInternal');
// Dispose logic specific to MyClass.
...
};
code »
getDisposed() ⇒
boolean
Use #isDisposed instead. No description.
Returns: 
boolean
  Whether the object has been disposed of.
code »
isDisposed() ⇒
boolean
No description.
Returns: 
boolean
  Whether the object has been disposed of.
code »
registerDisposable(disposable)
Associates a disposable object with this object so that they will be disposed together.
Arguments:
disposable :
(goog.disposable.IDisposable | null)
that will be disposed when this object is disposed.
code »

Instance Properties

Defined in goog.events.EventTarget
customEvent_ :
boolean
Used to tell if an event is a real event in goog.events.listen() so we don't get listen() calling addEventListener() and vice-versa.
Code »
parentEventTarget_ :
(goog.events.EventTarget | null)
Parent event target, used during event bubbling.
Code »
Defined in goog.Disposable
dependentDisposables_ :
(Array | null)
Disposables that should be disposed when this object is disposed.
Code »
disposed_ :
boolean
Whether the object has been disposed of.
Code »

Static Methods

goog.events.EventTarget.call()
No description.
code »

Package events

Package Reference