Bug 216149

Summary: Promises created from async functions don't resolve when document is detached.
Product: WebKit Reporter: John-David Dalton <john.david.dalton>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: ashvayka, cyb.ai.815, emilio, fpizlo, keith_miller, webkit-bug-importer, ysuzuki
Priority: P2 Keywords: InRadar
Version: Safari Technology Preview   
Hardware: Unspecified   
OS: Unspecified   

Description John-David Dalton 2020-09-03 15:27:10 PDT
The following snippet works in Chrome:

(async () => {
  var i = document.createElement('iframe');
  document.body.appendChild(i);
  var a = i.contentWindow.eval('(async () => await 1)');
  i.remove(); // someone removes the iframe
  const v = await a();
  console.log(v);
})();

Our use case has code that works when wired up and then someone removes the iframe and `await` no longer resolves.
Comment 1 Radar WebKit Bug Importer 2020-09-04 14:56:44 PDT
<rdar://problem/68367353>
Comment 2 Emilio Cobos Álvarez (:emilio) 2020-09-06 09:00:30 PDT
This might be a Chrome bug per spec, see: https://bugzilla.mozilla.org/show_bug.cgi?id=1663090#c3

(Though I haven't double-checked)
Comment 3 Yusuke Suzuki 2020-09-09 10:19:01 PDT
Currently, what we should do is not fully clarified in the spec.
It is ongoing discussion. But I think forever-pending promise would make sense since we should stop execution of script, and rejecting promise can involve script execution.
https://github.com/whatwg/html/issues/2621