Will there be support for signals for `fromEvent` and `fromEventPattern`?

[seniorkonung]

Currently, event binding is not sensitive to AbortSignal at all.

[trxcllnt]

What's wrong with using withAbort(), e.g. fromEvent(tgt, "evt").pipe(withAbort(sig))?

[seniorkonung]

What's wrong with using withAbort(), e.g. fromEvent(tgt, "evt").pipe(withAbort(sig))?

Is your signal with fromEvent working well? Actually, it's my assumption that it doesn't work, because I saw in the source code that it's based on fromEventPattern.

My problem is exactly with fromEventPattern.

import { fromEventPattern } from "ix/asynciterable"

const controller = new AbortController
setTimeout(() => {
    console.log("controller.abort()")
    controller.abort()
}, 8000)

let intervalId
fromEventPattern((handler) => {
    let count = 0
    intervalId = setInterval(() => handler(count++), 1000)
}, (_) => {
    console.log("clearInterval")
    clearInterval(intervalId)
})
.forEach(console.log, undefined, controller.signal)

Output:

0 0 AbortSignal { aborted: false }
1 1 AbortSignal { aborted: false }
2 2 AbortSignal { aborted: false }
3 3 AbortSignal { aborted: false }
4 4 AbortSignal { aborted: false }
5 5 AbortSignal { aborted: false }
6 6 AbortSignal { aborted: false }
controller.abort()
7 7 AbortSignal { aborted: true }
8 8 AbortSignal { aborted: true }
9 9 AbortSignal { aborted: true }
10 10 AbortSignal { aborted: true }
11 11 AbortSignal { aborted: true }
12 12 AbortSignal { aborted: true }
13 13 AbortSignal { aborted: true }

Expected behavior: the removeHandler closure fromEventPattern should be triggered when the signal is triggered. This does not happen.

I tried to do my own mini-investigation and found that the memoize operator does not pass the signal upstream. And it is memoize that the fromEventPattern operator is based on. This prevented me from writing my quick implementation of fromEventPattern, also based on memoize. But the signal was passed to the operator I created if I didn't use memoize.

But I was doing my mini-investigation at the time of publishing this issue and I'm speaking from memory. Besides, perhaps I didn't look deep enough into the matter, so these conclusions should be treated with skepticism.

There is only one fact: the fromEventPattern behavior does not match the user's expectations and does not cancel its behavior when the signal is triggered.

Platform: node v22.12.0
Version ix: 7.0.0

[trxcllnt]

Oh right, I forgot fromEventPattern uses memoize. The correct fix is to make memoize aggregate all its subscriber's cancellations and cancel upstream when they're all done. @mattpodwysocki