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Redefine fromAsync as “built-in async function” #50

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Merged
merged 9 commits into from
May 15, 2025
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Redefine fromAsync as “built-in async function” #50

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44515a6
Spec: First pass at conforming to "built-in async method" system
js-choi Apr 5, 2025
878c098
Build: Upgrade ecmarkup to v21.2.0
js-choi Apr 5, 2025
03af1b0
build: update ecma262-biblio to v2.1.2869
js-choi Apr 5, 2025
dffd3cb
editorial: change IfAbruptCloseAsyncIterator location
js-choi May 1, 2025
8d12a51
editorial: Change “Operations on Async Iterator Objects” to “Operatio…
js-choi May 1, 2025
2d69d2a
editorial: add an assert to IfAbruptCloseAsyncIterator
js-choi May 1, 2025
31f5096
editorial: Remove year from title
js-choi May 1, 2025
b1f7dc1
editorial: Add aoid attribute for IfAbruptCloseAsyncIterator
js-choi May 1, 2025
04d43c0
Editorial changes to match Array.from spec, esformat
js-choi May 1, 2025
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Spec: First pass at conforming to "built-in async method" system
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@js-choi
js-choi committed Apr 5, 2025
commit 44515a6d7e8d1d28a9b02b6774d4c28e9f2a5f3e
14 changes: 5 additions & 9 deletions spec.html
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Expand Up @@ -65,11 +65,9 @@ <h1><ins>Array.fromAsync ( _asyncItems_ [ , _mapper_ [ , _thisArg_ ] ] )</ins></
clause</a>.</p>
</emu-note>

<p>When the `fromAsync` method is called, the following steps are taken:</p>
<p>This async method performs the following steps when called:</p>
<emu-alg>
1. Let _C_ be the *this* value.
1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
1. Let _fromAsyncClosure_ be a new Abstract Closure with no parameters that captures _C_, _asyncItems_, _mapper_, and _thisArg_ and performs the following steps when called:
1. Let _C_ be the *this* value.
1. If _mapper_ is *undefined*, let _mapping_ be *false*.
1. Else,
1. If IsCallable(_mapper_) is *false*, throw a *TypeError* exception.
Expand Down Expand Up @@ -99,7 +97,7 @@ <h1><ins>Array.fromAsync ( _asyncItems_ [ , _mapper_ [ , _thisArg_ ] ] )</ins></
1. Let _done_ be ? IteratorComplete(_nextResult_).
1. If _done_ is *true*,
1. Perform ? Set(_A_, *"length"*, 𝔽(_k_), *true*).
1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _A_, [[Target]]: ~empty~ }.
1. Return _A_.
1. Let _nextValue_ be ? IteratorValue(_nextResult_).
1. If _mapping_ is *true*, then
1. Let _mappedValue_ be Call(_mapper_, _thisArg_, &laquo; _nextValue_, 𝔽(_k_) &raquo;).
Expand Down Expand Up @@ -130,12 +128,10 @@ <h1><ins>Array.fromAsync ( _asyncItems_ [ , _mapper_ [ , _thisArg_ ] ] )</ins></
1. Perform ? CreateDataPropertyOrThrow(_A_, _Pk_, _mappedValue_).
1. Set _k_ to _k_ + 1.
1. Perform ? Set(_A_, *"length"*, 𝔽(_len_), *true*).
1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _A_, [[Target]]: ~empty~ }.
1. Perform AsyncFunctionStart(_promiseCapability_, _fromAsyncClosure_).
1. Return _promiseCapability_.[[Promise]].
1. Return _A_.
</emu-alg>
<emu-note>
<p>The `fromAsync` function is an intentionally generic factory method; it does not require that its *this* value be the Array constructor. Therefore it can be transferred to or inherited by any other constructors that may be called with a single numeric argument.</p>
<p>This method is an intentionally generic factory method; it does not require that its *this* value be the Array constructor. Therefore it can be transferred to or inherited by any other constructors that may be called with a single numeric argument.</p>
</emu-note>
</emu-clause>
</emu-clause>
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