Unhandled rejection detection

[benjamingr]

If you'd like, implementing this API would be really awesome, Bluebird When and native promises on the server do this:

https://gist.github.com/benjamingr/0237932cee84712951a2

Cheers

[calvinmetcalf]

I have some very mixed feelings on this, on one hand it's an extremely useful feature on the other in's a non standard api so so this would no longer be a drop in replacement for native promises which can cause problems (see pouchdb/pouchdb#3839)

[benjamingr]

@calvinmetcalf it is a standard API in that everyone implements it, in fact native promises already do it in io.js and NodeJS accepted it but since the merger was declared they're just waiting for io.js to merge with node over the io.js codebase.

This is mostly useful in order to be compatible with native promises. nodejs/node#256

Documented here: https://iojs.org/api/process.html#process_event_unhandledrejection btw

Note that this mostly affects server-side usage.

[calvinmetcalf]

yeah it's browserify usage I'm thinking of that could be affected

[benjamingr]

Hmm how so? The code checks if process and process.emit are there and only emits the events then - it might be really nice to emit window events like bluebird does but that's not required of the spec.

You can see how I implemented this in Q here: kriskowal/q@1c38507

[calvinmetcalf]

if somebody does something like var Promise = global.Promise || require('lie'); you would or would not have events depending on your browser

[benjamingr]

@calvinmetcalf if someone does var Promise = global.Promise || require("lie"); you would not have events anyway since there is no process object.

These events already happen on the serverside in which case if a library is using lie instead of native promises they would not get errors. In fact you'd only get native errors if you do:

var p = Promise.reject(new Error(...)); // fires an event if no `catch` is attached within a microtask flush
var p = lie.reject(new Error(...)); // no process event, unlike native promises, Q, bluebird etc etc.

[calvinmetcalf]

let me look into how I can impliment it to work server side without increasing the client side code footprint unnecessarily

[benjamingr]

I was going to point out you can use a tool like envify and then use the fact minifiers strip dead code but it seems like you've figured something out already :) Thanks.

[calvinmetcalf]

Yeah the env seemed like a bit of a hack plus down stream packages could have used conflicting env stuff

[benjamingr]

Yes, the approach you took does sound better. Let me know if you need any help pushing this forward and thanks for doing this :)

[calvinmetcalf]

done in 2.9.0

[benjamingr]

Awesome, thanks a ton!

On Wed, May 27, 2015 at 2:53 PM, Calvin Metcalf [email protected]
wrote:

done in 2.9.0

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