`cleanupSome` Is Its Own Proposal Now
In Chapter 19 of the book ("A look ahead...") I cover the WeakRefs proposal, which at the time was Stage 3. As of the July 2020 meeting, WeakRefs is Stage 4 (yay!) — but
FinalizationRegistry.prototype.cleanupSome has been split off to its own proposal, currently at Stage 2.
There are a couple of reasons for it, but it's mostly to give people more time to be sure to get
cleanupSome right. There were some design changes to it late in WeakRefs' time at Stage 3 which could use some further thought, but moreover there are real questions about when, whether, and where to expose
Hesitation: When should
cleanupSomebe exposed on the Web?
The "long job" case doesn't quite make sense on the "window", the Web's main thread. It makes more sense for background Worker/Worklet threads. So, in browsers, it may make sense to exclude it from the window. There are several other Web Platform APIs which are only exposed in the context of certain global objects and not others, so this would follow a typical idiom.
. Further, Apple has raised concerns about
cleanupSomebeing exposed on the Web at all, due to concerns about whether we want to encourage the "long job" programming style in a context where objects are also being used.
Discussion about where and whether
cleanupSomeshould be exposed in web browsers is ongoing in a WHATWG HTML issue.
cleanupSomeinto a separate proposal would give everyone time to consider its presence in browsers at its own pace.
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