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AbortController.signal.addEventListener does not handle capture option #51703
Description
Activity
In chrome, it follows the order of registered event listener.
@climba03003 yes but I thought that
capture: trueoption should affect listener call order in the same way as in the DOM eventsIn Safari, like Firefox, the output is:
bar fooIt'd be interesting to pin down what the spec says about this.
/cc @nodejs/web-standards
Reacted by Dmitriy PetrovWhen set to true, options’s capture prevents callback from being invoked when the event’s eventPhase attribute value is BUBBLING_PHASE. When false (or not present), callback will not be invoked when event’s eventPhase attribute value is CAPTURING_PHASE. Either way, callback will be invoked if event’s eventPhase attribute value is AT_TARGET.
Node doesn't implement bubbling, because there's no tree-like structure that's hierarchical (think about an HTMLElement that can have children/a parent). Even if there was, AbortController/EventTarget has no hierarchy, and should ignore
captureregardless.Furthermore, here are the steps to invoke a callback (a callback is the user-supplied function when using addEventListener):
Note that an eventPhase, in node, can only beAT_TARGETorNONE[2] For each listener in listeners, whose removed is false:
[2.4] If phase is "bubbling" and listener’s capture is true, then continue.
...
[2.10] Call a user object’s operation with listener’s callback, "handleEvent", « event », and event’s currentTarget attribute value. If this throws an exception, then:There are a few important things to note here.
- addEventListener appends the callback to the list, not prepends
- the spec defines For each (step 2 above) as "performing a set of steps on each item in order," the in order is important here.
I'm not an expert at EventTarget, but it would appear as though node is correct, given the differences between browsers and servers. Maybe someone else can chime in who knows more.
This issue has been marked as stale due to 210 days of inactivity.
It will be automatically closed in 30 days if no further activity occurs. If this is still relevant, please leave a comment or update it to keep it open.I agree that there's no hierarchy in Node, but it seemed logical to me that if I add two listeners to a controller, one of which has capture:true, then regardless of the registration order, the one with capture:true will be called first.
However, overall, this isn't a problem for me, thanks for the clarification.
Version
v20.11.0
Platform
Linux petrov-dm 6.5.0-15-generic #15~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Jan 12 18:54:30 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
Subsystem
No response
What steps will reproduce the bug?
Run code:
How often does it reproduce? Is there a required condition?
No response
What is the expected behavior? Why is that the expected behavior?
expected output (like in firefox):
What do you see instead?
actual output:
Additional information
In Firefox there is properly behavior but i dont know how this described in specifications