Clarify when the rejectionhandled event does and does not fire

[sideshowbarker]

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Fixes https://github.com/mdn/content/issues/22177. @bergus it would great to have your review on this, if you can make time — since it’s based on your wording from https://stackoverflow.com/a/57261820/441757

[github-actions[bot]]

Preview URLs

• /en-US/docs/Web/API/Window/rejectionhandled_event

(this comment was updated 2022-11-25 08:37:34.917907)

[bergus]

I'd recommend to rather change the part "whenever a JavaScript Promise is rejected but after the promise rejection has been handled". I'd write

The **`rejectionhandled`** event is sent to the script's global scope (usually {{domxref("window")}} but also {{domxref("Worker")}}) whenever a rejected JavaScript {{jsxref("Promise")}} is handled late, after its rejections had caused an {{domxref("Window.unhandledrejection_event", "unhandledrejection")}} event, by subsequently attaching a handler.

This can be used in debugging and for general application resiliency, in tandem with the `unhandledrejection` event, which is sent when a promise is rejected but there is no handler for the rejection at the time.

[sideshowbarker]

@bergus Thanks much — made it so

[bergus]

@Josh-Cena It's usually not the unhandledrejection listener that would attach this handler, but some other code that still has a reference to the promise.

[bsmth]

Thanks, all. I will merge this shortly 👍🏻