| Package | flash.events |
| Class | public class UncaughtErrorEvent |
| Inheritance | UncaughtErrorEvent  ErrorEvent TextEvent Event Object |
| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10.1, AIR 2 |
try..catch blocks or when an ErrorEvent
object is dispatched with no registered listeners. The uncaught error event
functionality is often described as a "global error handler."
The UncaughtErrorEvents object that dispatches the event is associated with either a LoaderInfo object or a Loader object. Use the following properties to access an UncaughtErrorEvents instance:
-
LoaderInfo.uncaughtErrorEvents: to detect uncaught errors in code defined in the same SWF. -
Loader.uncaughtErrorEvents: to detect uncaught errors in code defined in the SWF loaded by a Loader object.
When an uncaughtError event happens, even if the event is handled,
execution does not continue in the call stack that caused the error. If the error is
a synchronous error, any code remaining in the function where the error happened is
not executed. Consequently, it is likely that when an uncaught error event happens,
your application is in an unstable state. Since there can be many causes for an
uncaught error, it is impossible to predict what functionality is available. For
example, your application may be able to execute network operations or file
operations. However, those operations aren't necessarily available.
When one SWF loads another, uncaughtError events bubble down and up
again through the LoaderInfo heirarchy. For example, suppose A.swf loads B.swf using a
Loader instance. If an uncaught error occurs in B.swf, an uncaughtError
event is dispatched to LoaderInfo and Loader objects in the following
sequence:
- (Capture phase) A.swf's LoaderInfo
- (Capture phase) Loader in A.swf
- (Target phase) B.swf's LoaderInfo
- (Bubble phase) Loader in A.swf
- (Bubble phase) A.swf's LoaderInfo
A Loader object's uncaughtErrorEvents property
never dispatches an uncaughtErrorEvent in the target phase. It only
dispatches the event in the capture and bubbling phases.
As with other event bubbling, calling stopPropagation() or
stopImmediatePropagation() stops the event from being dispatched
to any other listeners, with one important difference. A Loader object's
UncaughtErrorEvents object is treated as a pair with the loaded SWF's
LoaderInfo.uncaughtErrorEvents object for event propagation purposes.
If a listener registered with one of those objects calls the stopPropagation()
method, events are still dispatched to other listeners registered with that
UncaughtErrorEvents object and to listeners registered with its partner
UncaughtErrorEvents object before event propagation ends. The
stopImmediatePropagation() method still prevents events from being
dispatched to all additional listeners.
When content is running in a debugger version of the runtime, such as the
debugger version of Flash Player or the AIR Debug Launcher (ADL), an uncaught
error dialog appears when an uncaught error happens.
For those runtime versions, the error dialog appears even when a listener is registered
for the uncaughtError event. To prevent the dialog from appearing
in that situation, call the UncaughtErrorEvent object's
preventDefault() method.
If the content loaded by a Loader object is an AVM1 (ActionScript 2) SWF file,
uncaught errors in the AVM1 SWF file do not result in an uncaughtError
event. In addition, JavaScript errors in HTML content loaded in an HTMLLoader object
(including a Flex HTML control) do not result in an uncaughtError event.
Related API Elements
Hide Inherited Public Properties
Show Inherited Public Properties| Property | Defined By | ||
|---|---|---|---|
 | bubbles : Boolean [read-only]
Indicates whether an event is a bubbling event. | Event | |
| cancelable : Boolean [read-only]
Indicates whether the behavior associated with the event can be prevented. | Event | |
| constructor : Object
A reference to the class object or constructor function for a given object instance. | Object | |
| currentTarget : Object [read-only]
The object that is actively processing the Event object with an event listener. | Event | |
| error : * [read-only]
The error object associated with the uncaught error. | UncaughtErrorEvent | ||
| errorID : int [read-only]
Contains the reference number associated with the specific error. | ErrorEvent | |
| eventPhase : uint [read-only]
The current phase in the event flow. | Event | |
| target : Object [read-only]
The event target. | Event | |
| text : String
For a textInput event, the character or sequence of characters
entered by the user. | TextEvent | |
| type : String [read-only]
The type of event. | Event | |
| Method | Defined By | ||
|---|---|---|---|
UncaughtErrorEvent(type:String, bubbles:Boolean = true, cancelable:Boolean = true, error_in:* = null)
Creates an UncaughtErrorEvent object that contains information about an
uncaughtError event. | UncaughtErrorEvent | ||
[override]
Creates a copy of the UncaughtErrorEvent object and sets the value of
each property to match that of the original. | UncaughtErrorEvent | ||
|
A utility function for implementing the toString() method in custom
ActionScript 3.0 Event classes. | Event | |
|
Indicates whether an object has a specified property defined. | Object | |
|
Checks whether the preventDefault() method has been called on the event. | Event | |
|
Indicates whether an instance of the Object class is in the prototype chain of the object specified
as the parameter. | Object | |
|
Cancels an event's default behavior if that behavior can be canceled. | Event | |
|
Indicates whether the specified property exists and is enumerable. | Object | |
|
Sets the availability of a dynamic property for loop operations. | Object | |
|
Prevents processing of any event listeners in the current node and any subsequent nodes in
the event flow. | Event | |
|
Prevents processing of any event listeners in nodes subsequent to the current node in the
event flow. | Event | |
|
Returns the string representation of this object, formatted according to locale-specific conventions. | Object | |
[override]
Returns a string that contains all the properties of the UncaughtErrorEvent object. | UncaughtErrorEvent | ||
|
Returns the primitive value of the specified object. | Object | |
| Constant | Defined By | ||
|---|---|---|---|
| UNCAUGHT_ERROR : String = "uncaughtError" [static]
Defines the value of the type property of an uncaughtError event object. | UncaughtErrorEvent | ||
error | property |
error:* [read-only] | Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10.1, AIR 2 |
The error object associated with the uncaught error. Typically, this object's data type is one of the following:
- An Error instance (or one of its subclasses), if the uncaught error is
a synchronous error created by a
throwstatement, such as an error that could have been caught using atry..catchblock - An ErrorEvent instance (or one of its subclasses), if the uncaught error is an asynchronous error that dispatches an error event when the error happens
However, the error property can potentially be an object of any
data type. ActionScript does not require a throw
statement to be used only with Error objects. For example, the following
code is legal both at compile time and run time:
throw new Sprite()
If that throw statement is not caught by a
try..catch block, the throw statement
triggers an uncaughtError event. In that case, the
error property of the UncaughtErrorEvent object that's dispatched
is the Sprite object that's constructed in the throw statement.
Consequently, in your uncaughtError listener, you should check
the data type of the error property. The following example
demonstrates this check:
function uncaughtErrorHandler(event:UncaughtErrorEvent):void
{
var message:String;
if (event.error is Error)
{
message = Error(event.error).message;
}
else if (event.error is ErrorEvent)
{
message = ErrorEvent(event.error).text;
}
else
{
message = event.error.toString();
}
}If the error property contains an Error instance (or Error subclass),
the available error information varies depending on the version of the runtime
in which the content is running, as follows:
In a debugger version of the runtime such as the debugger version of Flash Player or the AIR Debug Launcher (ADL):
- The
Error.getStackTrace()method returns the call stack that led to the error - The
Error.messagecontains the complete error message text
- The
In a non-debuger version of the runtime:
- The
Error.getStackTrace()method returns the call stack that led to the error. However, the call stack information doesn't include source file names or line numbers. - The
Error.messageproperty contains a short version of the error message, which is oftan a combination of theError.errorIDandError.nameproperties
- The
In a non-debugger version of the runtime (Flash Player 11.4 or earlier and AIR 1.4 or earlier):
- The
Error.getStackTrace()method returnsnull - The
Error.messageproperty contains a short version of the error message, which is oftan a combination of theError.errorIDandError.nameproperties
- The
All other properties and methods of the Error class are available in all runtime versions.
Note that if the error property is an ErrorEvent
instance, call stack information is never available.
Implementation
public function get error():*UncaughtErrorEvent | () | Constructor |
public function UncaughtErrorEvent(type:String, bubbles:Boolean = true, cancelable:Boolean = true, error_in:* = null)| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10.1, AIR 2 |
Creates an UncaughtErrorEvent object that contains information about an
uncaughtError event.
type:String (default = NaN) | |
bubbles:Boolean (default = true)bubbles property.
| |
cancelable:Boolean (default = true)cancelable property.
| |
error_in:* (default = null) |
clone | () | method |
override public function clone():Event| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10.1, AIR 2 |
Creates a copy of the UncaughtErrorEvent object and sets the value of each property to match that of the original.
ReturnsEvent — A new UncaughtErrorEvent object with property values that match those
of the original.
|
toString | () | method |
UNCAUGHT_ERROR | Constant |
public static const UNCAUGHT_ERROR:String = "uncaughtError"| Language Version: | ActionScript 3.0 |
| Runtime Versions: | Flash Player 10.1, AIR 2 |
Defines the value of the type property of an uncaughtError event object.
Note: If in a try block, there is an event dispatcher that calls its event handler,
the catch block doesn't catch the error if thrown in event handler. Any error thrown
thereafter can be caught by listening to LoaderInfo.uncaughtErrorEvents.
This event has the following properties:
| Property | Value |
|---|---|
bubbles | true |
cancelable | true; cancelling the event prevents the uncaught error dialog from appearing in debugger runtime versions |
currentTarget | The object that is actively processing the Event object with an event listener. |
error | The uncaught error. |
target | The LoaderInfo object associated with the SWF where the error happened. |
text | Text error message. |
uncaughtError event handler to detect uncaught errors. It also
provides a button that, when clicked, throws an error that is caught by the
uncaught error handler.
In the constructor, the code registers a listener for the uncaughtError
event dispatched by the LoaderInfo object's uncaughtErrorEvents property.
In the uncaughtErrorHandler() method, the code checks the data type of
the error property and responds accordingly.
package
{
import flash.display.Sprite;
import flash.events.ErrorEvent;
import flash.events.MouseEvent;
import flash.events.UncaughtErrorEvent;
public class UncaughtErrorEventExample extends Sprite
{
public function UncaughtErrorEventExample()
{
loaderInfo.uncaughtErrorEvents.addEventListener(UncaughtErrorEvent.UNCAUGHT_ERROR, uncaughtErrorHandler);
drawUI();
}
private function uncaughtErrorHandler(event:UncaughtErrorEvent):void
{
if (event.error is Error)
{
var error:Error = event.error as Error;
// do something with the error
}
else if (event.error is ErrorEvent)
{
var errorEvent:ErrorEvent = event.error as ErrorEvent;
// do something with the error
}
else
{
// a non-Error, non-ErrorEvent type was thrown and uncaught
}
}
private function drawUI():void
{
var btn:Sprite = new Sprite();
btn.graphics.clear();
btn.graphics.beginFill(0xFFCC00);
btn.graphics.drawRect(0, 0, 100, 50);
btn.graphics.endFill();
addChild(btn);
btn.addEventListener(MouseEvent.CLICK, clickHandler);
}
private function clickHandler(event:MouseEvent):void
{
throw new Error("Gak!");
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<s:WindowedApplication xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/halo"
applicationComplete="applicationCompleteHandler();">
<fx:Script>
<![CDATA[
import flash.events.ErrorEvent;
import flash.events.MouseEvent;
import flash.events.UncaughtErrorEvent;
private function applicationCompleteHandler():void
{
loaderInfo.uncaughtErrorEvents.addEventListener(UncaughtErrorEvent.UNCAUGHT_ERROR, uncaughtErrorHandler);
}
private function uncaughtErrorHandler(event:UncaughtErrorEvent):void
{
if (event.error is Error)
{
var error:Error = event.error as Error;
// do something with the error
}
else if (event.error is ErrorEvent)
{
var errorEvent:ErrorEvent = event.error as ErrorEvent;
// do something with the error
}
else
{
// a non-Error, non-ErrorEvent type was thrown and uncaught
}
}
private function clickHandler(event:MouseEvent):void
{
throw new Error("Gak!");
}
]]>
</fx:Script>
<s:Button label="Cause Error" click="clickHandler(event);"/>
</s:WindowedApplication>
uncaughtError event handler to detect uncaught errors.
In the constructor, the code creates a Loader object and registers a listener for
the uncaughtError event dispatched by the Loader object's
uncaughtErrorEvents property.
In the uncaughtErrorHandler() method, the code checks the data type of
the error property and responds accordingly.
package
{
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.ErrorEvent;
import flash.events.UncaughtErrorEvent;
import flash.net.URLRequest;
public class LoaderUncaughtErrorEventExample extends Sprite
{
private var ldr:Loader;
public function LoaderUncaughtErrorEventExample()
{
ldr = new Loader();
ldr.load(new URLRequest("child.swf"));
ldr.uncaughtErrorEvents.addEventListener(UncaughtErrorEvent.UNCAUGHT_ERROR, uncaughtErrorHandler);
}
private function uncaughtErrorHandler(event:UncaughtErrorEvent):void
{
if (event.error is Error)
{
var error:Error = event.error as Error;
// do something with the error
}
else if (event.error is ErrorEvent)
{
var errorEvent:ErrorEvent = event.error as ErrorEvent;
// do something with the error
}
else
{
// a non-Error, non-ErrorEvent type was thrown and uncaught
}
}
}
}
Wed Nov 21 2018, 06:34 AM -08:00