jQuery Deferreds, .pipe and exceptions

Question

I have code that looks somewhat like this (less ridiculous, of course):

var d = $.Deferred();
d.pipe(function() {
    throw "a";
}).then(function() {
    console.log("good!");
}, function(e) {
    console.log("I want the exception here");
});
d.resolve();

The problem is that throwing an exception in a .pipe doneFilter does not seem to make jQuery consider it as a failure and it results in an uncaught exception in the doneFilter.

An alternative is to create a new deferred and throw a try-catch block around the doneFilter, but I was wondering if there was a better way to go about it.

I'm confused because your example does not use either `.pipe()` or `doneFilter` which you then go on to talk about `\-:` — hippietrail, Aug 08 '12 at 10:01

glortho · Accepted Answer · 2012-01-10T06:52:18.727

2

If you have to use throw, it is indeed best to catch it in the doneFilter, and return $.Deferred().reject('a') (or whatever) from it on error. The fail callback in then will then be called with the arg you pass.

edited Jan 10 '12 at 06:52

answered Jan 10 '12 at 06:24

glortho

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Could you elaborate on this? There's apparently no such thing as `$.Deferred.reject`. – Jan 10 '12 at 06:49
Sorry, typo. Edited to fix: `$.Deferred()` – glortho Jan 10 '12 at 06:52
1

Why isn't this default behavior :-( https://github.com/kriskowal/q has it by default. – w00t Mar 18 '13 at 15:11
Here (http://stackoverflow.com/a/13611929/123897) is a good comparison between Promises/A and jQuery Deferred. – jpbochi Jul 31 '13 at 22:07

jQuery Deferreds, .pipe and exceptions

1 Answers1