Hacktoberfest 2026: le issue che i maintainer hanno segnato per ottobre, aperte e adatte ai principianti. Sfoglia le issue Hacktoberfest

Detect unhandled promise rejections

Aperta
  • Qualcosa non va?
#82 3 commenti 0 reazioni 0 assegnatari Vedi su GitHub

Nessuno ha ancora preso questa issue.

Valutazione

Difficoltà
5/5
Tempo stimato
Più di una settimana
Idoneità per principianti
25/100
Tipo di issue
Funzionalità
Chiarezza
Abbastanza chiara
Stato di attività
Ferma
Stack tecnologico
javascript, ruby
Ambito
api, backend

Direzione di ricerca

The issue points to V8's SetPromiseRejectCallback and PromiseRejectMessage; start by reading those API definitions and locating how mini_racer connects V8 callbacks to Ruby exceptions. The example shows the missed rejection and the expected error behavior, while the issue leaves the default behavior and configurability undecided. Done means unhandled rejections are reported to Ruby, with the handling behavior defined.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

When working with promises, one important aspect of them is that an unhandled rejected promise is an error. However, V8 will drop notifications by default.

I think that mini_racer should consider this an error and raise an exception, though possibly it should be configurable how these are handled (e.g. via a callback where the user can decide to re-raise?).

To do so, it's necessary to register for unhandled promise rejections via SetPromiseRejectCallback.

The callback will receive a PromiseRejectMessage that should probably (by default) raise a exception in ruby, although I suppose it could be configurable.

Comparisons for reference:

Running this code:

var x = async () => { throw "failure"; };
var y = async () => { x() /* ignore the rejected result */ }; 
y().then(() => console.log("done")).catch(e => console.log(e));

In node:

> var x = async () => { throw "failure"; }; var y = async () => { x() /* ignore the rejected result */ }; y().then(() => console.log("done")).catch(e => console.log(e));
Promise {
  <pending>,
  domain:
   Domain {
     domain: null,
     _events:
      { removeListener: [Function: updateExceptionCapture],
        newListener: [Function: updateExceptionCapture],
        error: [Function: debugDomainError] },
     _eventsCount: 3,
     _maxListeners: undefined,
     members: [] } }
> done
(node:83056) UnhandledPromiseRejectionWarning: failure
(node:83056) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)

In chrome:

var x = async () => { throw "failure"; }; var y = async () => { x() /* ignore the rejected result */ }; y().then(() => console.log("done")).catch(e => console.log(e));
VM131:1 done
Promise {<resolved>: undefined}
VM131:1 Uncaught (in promise) failure

In mini_racer:

irb(main):001:0> require 'mini_racer'
=> true
irb(main):002:0> vm = MiniRacer::Context.new
=> #<MiniRacer::Context:0x00007ff4350f1438 @functions={}, @timeout=nil, @max_memory=nil, @current_exception=nil, @isolate=#<MiniRacer::Isolate:0x00007ff4350f12f8 @lock=#<Thread::Mutex:0x00007ff4350f12a8>>, @disposed=false, @callback_mutex=#<Thread::Mutex:0x00007ff4350f1280>, @callback_running=false, @thread_raise_called=false, @eval_thread=nil>
irb(main):003:0> vm.attach('console.log', proc{ |*args| puts('LOG> ' + args.map(&:to_s).join(' ')) })
=> #<MiniRacer::Context::ExternalFunction:0x00007ff43602b1b0 @name="log", @callback=#<Proc:0x00007ff43602b200@/usr/local/lib/ruby/gems/2.5.0/gems/mini_racer-0.1.15/lib/mini_racer.rb:201 (lambda)>, @parent=#<MiniRacer::Context:0x00007ff4350f1438 @functions={"console.log"=>#<MiniRacer::Context::ExternalFunction:0x00007ff43602b1b0 ...>}, @timeout=nil, @max_memory=nil, @current_exception=nil, @isolate=#<MiniRacer::Isolate:0x00007ff4350f12f8 @lock=#<Thread::Mutex:0x00007ff4350f12a8>>, @disposed=false, @callback_mutex=#<Thread::Mutex:0x00007ff4350f1280>, @callback_running=false, @thread_raise_called=false, @eval_thread=nil>, @parent_object_eval="if (typeof console === 'undefined') { console = {} };\nconsole;", @parent_object="console">
irb(main):004:0> vm.eval('var x = async () => { throw "failure"; }; var y = async () => { x() /* ignore the rejected result */ }; y().then(() => console.log("done")).catch(e => console.log(e));')
LOG> done
=> {}
irb(main):005:0>
Lingua principale
JavaScript
Stelle
628
Fork
100
Merge medio
1g 20h
PR unite (30g)
2

Preparare l'ambiente

  • Include un Dockerfile o un file Docker Compose
  • Nessun modello di pull request
  • Nessuna guida per i contributori

Come iniziare

  1. Leggi tutta la issue e poi la guida ai contributi del progetto.
  2. Commenta sulla issue per dire che te ne occupi tu — evita che due persone facciano lo stesso lavoro.
  3. Fai un fork del repository e lavora su un branch.
  4. Apri una pull request che faccia riferimento al numero della issue.

Altre issue di rubyjs/mini_racer

Tutte le issue di rubyjs/mini_racer

Issue simili

Altre issue su JavaScript

Ricevi le nuove issue nella tua casella

Un breve riepilogo di issue GitHub adatte ai principianti.