[TIMOB-1057] iOS: Exceptions failing in event listeners

GitHub Issue	n/a
Type	Bug
Priority	Medium
Status	Closed
Resolution	Cannot Reproduce
Resolution Date	2012-07-25T12:43:24.000+0000
Affected Version/s	Release 1.5.0
Fix Version/s	n/a
Components	iOS
Labels	n/a
Reporter	ctredway
Assignee	Neeraj Gupta
Created	2011-04-15T02:42:45.000+0000
Updated	2012-07-26T22:25:12.000+0000

Description

a customer has reported that if there is a coding issue (i.e. missing var) in an event listener, that error fails to be registered in Developer. Following code shows this behavior.

var i=0;
i.missingMethod();

appropriately logs the exception but

btn.addEventListener('click', function() {
var i=0;
i.missingMethod();
});

does not.

Comments

Stephen Tramer 2011-04-15

This is a threading issue, certainly. We don't catch and report exceptions that occur on some threads.

Damien Elmes 2011-04-15

I hit this issue so often that I don't call addEventListener() directly anymore, and instead use:

   var listen = function(obj, event, cb) {
       obj.addEventListener(event, function (e) {
                                try {
                                    cb(e);
                                } catch (err) {
                                    alert("Error in callback: " + err);
                                }
                            });
   };

Matthew Lieder 2011-04-15

That's a great idea Damien; I'm embarrassed I never even thought of doing that. Keep forgetting how flexible Javascript is. Thanks! That'll be a great duct-tape bandage until they fix this.
David Rodriguez 2011-12-18

Is there any way to do a stack trace with a try and catch?

Stephen Tramer 2012-07-25

Cannot reproduce described issue in SDK 2.2.0.f9e938d with iPhone Sim 5.1.

   var i=0;
   i.missingMethod();
   
   appropriately logs the exception but
   
   btn.addEventListener('click', function() {
   var i=0;
   i.missingMethod();
   });

This logs information in the console indicating an exception has occurred.

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