StructureJS
0.15.2A class based utility library for building modular and scalable web platform applications. Features opt-in classes and utilities which provide a solid foundation and toolset to build your next project.
EventDispatcher Class
EventDispatcher is the base class for all classes that dispatch events. It is the base class for the DisplayObjectContainer class. EventDispatcher provides methods for managing prioritized queues of event listeners and dispatching events.
Index
Show:
Properties
Properties
_listeners
Any
protected
Holds a reference to added listeners.
isEnabled
Boolean
public
The isEnabled property is used to keep track of the enabled state of the object.
Default: false
parent
Any
public
Indicates the object that contains a child object. Uses the parent property to specify a relative path to display objects that are above the current display object in the display list hierarchy and helps facilitate event bubbling.
sjsId
Int
public
The sjsId (StructureJS ID) is a unique identifier automatically assigned to most StructureJS objects upon instantiation.
Default: null
Constructor
EventDispatcher
()
Example:
// Another way to use the EventDispatcher.
let eventDispatcher = new EventDispatcher();
eventDispatcher.addEventListener('change', this._handlerMethod, this);
eventDispatcher.dispatchEvent('change');Methods
addEventListener
(
-
type
-
callback
-
scope
-
[priority=0]
)
public
chainable
-
type -
callback -
scope -
[priority=0]
Registers an event listener object with an EventDispatcher object so the listener receives notification of an event.
Parameters:
-
typeStringThe type of event.
-
callbackFunctionThe listener function that processes the event. This function must accept an Event object as its only parameter and must return nothing, as this example shows. @example function(event:Event):void
-
scopeAnyBinds the scope to a particular object (scope is basically what "this" refers to in your function). This can be very useful in JavaScript because scope isn't generally maintained.
-
[priority=0]Int optionalInfluences the order in which the listeners are called. Listeners with lower priorities are called after ones with higher priorities.
Example:
this.addEventListener(BaseEvent.CHANGE, this._handlerMethod, this);
_handlerMethod(event) {
console.log(event.target + " sent the event.");
console.log(event.type, event.data);
}addEventListenerOnce
(
-
type
-
callback
-
scope
-
[priority=0]
)
public
chainable
-
type -
callback -
scope -
[priority=0]
Registers an event listener object once with an EventDispatcher object so the listener will receive the notification of an event.
Parameters:
-
typeStringThe type of event.
-
callbackFunctionThe listener function that processes the event. This function must accept an Event object as its only parameter and must return nothing, as this example shows. @example function(event:Event):void
-
scopeAnyBinds the scope to a particular object (scope is basically what "this" refers to in your function). This can be very useful in JavaScript because scope isn't generally maintained.
-
[priority=0]Int optionalInfluences the order in which the listeners are called. Listeners with lower priorities are called after ones with higher priorities.
Example:
this.addEventListenerOnce(BaseEvent.CHANGE, this._handlerMethod, this);
_handlerMethod(event) {
console.log(event.target + " sent the event.");
console.log(event.type, event.data);
}destroy
()
Void
public
The purpose of the destroy method is to make an object ready for garbage collection. This should be thought of as a one way function. Once destroy is called no further methods should be called on the object or properties accessed. It is the responsibility of those who implement this function to stop all running Timers, all running Sounds, and take any other steps necessary to make an object eligible for garbage collection.
By default the destroy method will null out all properties of the class automatically. You should call destroy on other objects before calling the super.
Returns:
Void:
Example:
destroy() {
this.disable();
this._childInstance.destroy();
super.destroy();
}disable
()
public
chainable
The disable method is responsible for disabling event listeners and/or children of the containing objects.
Example:
disable() {
if (this.isEnabled === false) { return; }
this._childInstance.removeEventListener(BaseEvent.CHANGE, this.handlerMethod, this);
this._childInstance.disable();
super.disable();
}dispatchEvent
(
-
event
-
[data=null]
)
public
chainable
-
event -
[data=null]
Dispatches an event into the event flow. The event target is the EventDispatcher object upon which the dispatchEvent() method is called.
Parameters:
-
eventString | BaseEventThe Event object or event type string you want to dispatch. You can create custom events, the only requirement is all events must extend BaseEvent.
-
[data=null]Any optionalThe optional data you want to send with the event. Do not use this parameter if you are passing in a BaseEvent.
Example:
this.dispatchEvent('change');
// Example: Sending data with the event:
this.dispatchEvent('change', {some: 'data'});
// Example: With an event object
// (event type, bubbling set to true, cancelable set to true and passing data) :
let event = new BaseEvent(BaseEvent.CHANGE, true, true, {some: 'data'});
this.dispatchEvent(event);
// Here is a common inline event object being dispatched:
this.dispatchEvent(new BaseEvent(BaseEvent.CHANGE));enable
()
public
chainable
The enable method is responsible for enabling event listeners and/or children of the containing objects.
Example:
enable() {
if (this.isEnabled === true) { return; }
this._childInstance.addEventListener(BaseEvent.CHANGE, this.handlerMethod, this);
this._childInstance.enable();
super.enable();
}getEventListeners
()
Array
Returns and array of all current event types and there current listeners.
Returns:
Array
Example:
this.getEventListeners();getQualifiedClassName
()
String
public
Returns the fully qualified class name of an object.
Returns:
String:
Returns the class name.
Example:
let someClass = new SomeClass();
someClass.getQualifiedClassName();
// SomeClasshasEventListener
(
-
type
-
callback
-
scope
)
Boolean
public
-
type -
callback -
scope
print
()
String
public
Prints out each event listener in the console.log
Returns:
Example:
this.printEventListeners();
// [ClassName] is listening for the 'BaseEvent.change' event.
// [AnotherClassName] is listening for the 'BaseEvent.refresh' event.removeEventListener
(
-
type
-
callback
-
scope
)
public
chainable
-
type -
callback -
scope