window.runtime property	window.runtime.flash.events.UncaughtErrorEvent
Inheritance	UncaughtErrorEvent ErrorEvent TextEvent Event Object

Runtime Versions:

2

An UncaughtErrorEvent object is dispatched by an instance of the UncaughtErrorEvents class when an uncaught error occurs. An uncaught error happens when an error is thrown outside of any 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:

1. (Capture phase) A.swf's LoaderInfo
2. (Capture phase) Loader in A.swf
3. (Target phase) B.swf's LoaderInfo
4. (Bubble phase) Loader in A.swf
5. (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.

See also

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throw new Sprite()

         function uncaughtErrorHandler(event)

         {

             var message; // String

             

             if (event.error.message) // It's an Error object

             {

                 message = event.error.message;

             }

             else if (event.error.text) // It's an ErrorEvent object

             {

                 message = event.error.text;

             }

             else

             {

                 message = event.error.toString();

             }

         }