jQuery Forum

Can you point out some specific places in jQuery where it swallows exceptions when it shouldn't? There are several try/catch cases that work around specific issues (mostly with IE) but it really does want to ignore them.

As of 1.4 there is a jQuery.error method used internally to throw specific errors. By default it simply uses throw and you'd need to wrap the specific operation to catch it. You can override that if you want to do custom handling (for example, console.write the errors but otherwise continue). However, jQuery isn't trying to ensure that all invalid inputs throw an error. That would be a very ambitious project.

If you check the bug tracker you will notice that at least several times a month someone recommends "fixing" an IE exception by putting try/catch around it in jQuery. I think that $("#myel").attr("width", "autopx") deserves to die a noisy death but it seems a lot of people want it to be silently ignored.

Edit: Speak of the devil!  http://dev.jquery.com/ticket/6524

After creating some minimal test cases, it appears both $.ajax callbacks and click events are doing the right thing, raising the respective exception rather than failing silently:

1. $.ajax({
2.     url: uri,
3.     type: "GET",
4.     success: function(data, status, xhr) {
5.         console.log("foo");
6.         throw "error";
7.         console.log("bar");
8.     },
9.     error: console.log
10. });

I've encountered the issue of exceptions being swallowed numerous times over the last couple of months, in various different contexts (so not just one particular application or version of jQuery). After some conversations on IRC, I was led to believe that this is simply what jQuery does - which is why, foolishly, I didn't create a reduced test case in the first place.

Clearly there's something strange going on, and it's possible I'm simply Doing It Wrong somewhere. So for the moment, please ignore me - I'll revive this thread once I got more solid information to provide. My apologies for the distraction.

In 1.2.something there was a bug where if an error occurred in an ajax success handler (or throw was used as in your example) it would end up calling the error handler with "parsererror" as the reason. Maybe that's what you saw? For the purposes of this investigation it would be best to use 1.4.2 since that's the version we'd be fixing.