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Normative: Remove Species check for TypedArrays ArrayBuffers and SharedArrayBuffers #3450

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Normative: Remove Species check for TypedArrays ArrayBuffers and SharedArrayBuffers #3450

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Normative: Remove Species check for TypedArrays ArrayBuffers and Shar…
Oct 16, 2024
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address review comments
Oct 17, 2024
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address formatting issues
Oct 23, 2024
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41 changes: 13 additions & 28 deletions spec.html
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Original file line number Diff line number Diff line change
Expand Up @@ -6572,6 +6572,12 @@ <h1>
1. If IsConstructor(_S_) is *true*, return _S_.
1. Throw a *TypeError* exception.
</emu-alg>
<emu-note>
<p>Species constructor is only available for Array, RegExp and Promise built-in classes. It
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<p>Species constructor is only available for Array, RegExp and Promise built-in classes. It
<p>Species constructor is only available for Array, RegExp, and Promise built-in classes. It

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<p>Species constructor is only available for Array, RegExp, and Promise built-in classes. </p>
<p>Species constructor is only available for Array, RegExp, and Promise built-in classes.</p>

will not be provided to any other built-in classes. Species are an expensive and complex
operation that did not end up being used by the community, resulting in the feature being
deprecated.</p>
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Editors discussed this and we think that capturing "we aren't going to do this anymore" probably doesn't belong in the spec itself. Instead, how-we-work/normative-conventions.md would be a good place for capturing this for the committee's benefit, and MDN for the community's.

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Should this note be removed entirely or should the comment about species constructor availability stay?

</emu-note>
</emu-clause>

<emu-clause id="sec-enumerableownproperties" type="abstract operation" oldids="sec-enumerableownpropertynames">
Expand Down Expand Up @@ -40793,7 +40799,7 @@ <h1>%TypedArray%.prototype.filter ( _callback_ [ , _thisArg_ ] )</h1>
1. Append _kValue_ to _kept_.
1. Set _captured_ to _captured_ + 1.
1. Set _k_ to _k_ + 1.
1. Let _A_ be ? TypedArraySpeciesCreate(_O_, « 𝔽(_captured_) »).
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_captured_) »).
1. Let _n_ be 0.
1. For each element _e_ of _kept_, do
1. Perform ! Set(_A_, ! ToString(𝔽(_n_)), _e_, *true*).
Expand Down Expand Up @@ -41019,7 +41025,7 @@ <h1>%TypedArray%.prototype.map ( _callback_ [ , _thisArg_ ] )</h1>
1. Let _taRecord_ be ? ValidateTypedArray(_O_, ~seq-cst~).
1. Let _len_ be TypedArrayLength(_taRecord_).
1. If IsCallable(_callback_) is *false*, throw a *TypeError* exception.
1. Let _A_ be ? TypedArraySpeciesCreate(_O_, « 𝔽(_len_) »).
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_len_) »).
1. Let _k_ be 0.
1. Repeat, while _k_ &lt; _len_,
1. Let _Pk_ be ! ToString(𝔽(_k_)).
Expand Down Expand Up @@ -41235,7 +41241,7 @@ <h1>%TypedArray%.prototype.slice ( _start_, _end_ )</h1>
1. Else if _relativeEnd_ &lt; 0, let _endIndex_ be max(_srcArrayLength_ + _relativeEnd_, 0).
1. Else, let _endIndex_ be min(_relativeEnd_, _srcArrayLength_).
1. Let _countBytes_ be max(_endIndex_ - _startIndex_, 0).
1. Let _A_ be ? TypedArraySpeciesCreate(_O_, « 𝔽(_countBytes_) »).
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_countBytes_) »).
1. If _countBytes_ > 0, then
1. Set _taRecord_ to MakeTypedArrayWithBufferWitnessRecord(_O_, ~seq-cst~).
1. If IsTypedArrayOutOfBounds(_taRecord_) is *true*, throw a *TypeError* exception.
Expand Down Expand Up @@ -41347,7 +41353,7 @@ <h1>%TypedArray%.prototype.subarray ( _start_, _end_ )</h1>
1. Else, let _endIndex_ be min(_relativeEnd_, _srcLength_).
1. Let _newLength_ be max(_endIndex_ - _startIndex_, 0).
1. Let _argumentsList_ be « _buffer_, 𝔽(_beginByteOffset_), 𝔽(_newLength_) ».
1. Return ? TypedArraySpeciesCreate(_O_, _argumentsList_).
1. Return ? TypedArrayCreateSameType(_O_, _argumentsList_).
</emu-alg>
<p>This method is not generic. The *this* value must be an object with a [[TypedArrayName]] internal slot.</p>
</emu-clause>
Expand Down Expand Up @@ -41465,27 +41471,6 @@ <h1>get %TypedArray%.prototype [ %Symbol.toStringTag% ]</h1>
<emu-clause id="sec-abstract-operations-for-typedarray-objects">
<h1>Abstract Operations for TypedArray Objects</h1>

<emu-clause id="typedarray-species-create" type="abstract operation">
<h1>
TypedArraySpeciesCreate (
_exemplar_: a TypedArray,
_argumentList_: a List of ECMAScript language values,
): either a normal completion containing a TypedArray or a throw completion
</h1>
<dl class="header">
<dt>description</dt>
<dd>It is used to specify the creation of a new TypedArray using a constructor function that is derived from _exemplar_. Unlike ArraySpeciesCreate, which can create non-Array objects through the use of %Symbol.species%, this operation enforces that the constructor function creates an actual TypedArray.</dd>
</dl>
<emu-alg>
1. Let _defaultConstructor_ be the intrinsic object associated with the constructor name _exemplar_.[[TypedArrayName]] in <emu-xref href="#table-the-typedarray-constructors"></emu-xref>.
1. Let _constructor_ be ? SpeciesConstructor(_exemplar_, _defaultConstructor_).
1. Let _result_ be ? TypedArrayCreateFromConstructor(_constructor_, _argumentList_).
1. Assert: _result_ has [[TypedArrayName]] and [[ContentType]] internal slots.
1. If _result_.[[ContentType]] is not _exemplar_.[[ContentType]], throw a *TypeError* exception.
1. Return _result_.
</emu-alg>
</emu-clause>

<emu-clause id="sec-typedarraycreatefromconstructor" oldids="typedarray-create" type="abstract operation">
<h1>
TypedArrayCreateFromConstructor (
Expand Down Expand Up @@ -41517,7 +41502,7 @@ <h1>
</h1>
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<dl class="header">
<dt>description</dt>
<dd>It is used to specify the creation of a new TypedArray using a constructor function that is derived from _exemplar_. Unlike TypedArraySpeciesCreate, which can construct custom TypedArray subclasses through the use of %Symbol.species%, this operation always uses one of the built-in TypedArray constructors.</dd>
<dd>It is used to specify the creation of a new TypedArray using a constructor function that is derived from _exemplar_. This operation always uses one of the built-in TypedArray constructors.</dd>
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<dd>It is used to specify the creation of a new TypedArray using a constructor function that is derived from _exemplar_. This operation always uses one of the built-in TypedArray constructors.</dd>
<dd>It is used to specify the creation of a new TypedArray using a constructor function that is derived from _exemplar_. This operation always uses one of the built-in TypedArray constructors. Prior to the 2025 edition of the specification some TypedArray methods made use of SpeciesCreate, but that functionality has been removed.</dd>

</dl>
<emu-alg>
1. Let _constructor_ be the intrinsic object associated with the constructor name _exemplar_.[[TypedArrayName]] in <emu-xref href="#table-the-typedarray-constructors"></emu-xref>.
Expand Down Expand Up @@ -43807,7 +43792,7 @@ <h1>ArrayBuffer.prototype.slice ( _start_, _end_ )</h1>
1. Else if _relativeEnd_ &lt; 0, let _final_ be max(_len_ + _relativeEnd_, 0).
1. Else, let _final_ be min(_relativeEnd_, _len_).
1. Let _newLen_ be max(_final_ - _first_, 0).
1. Let _ctor_ be ? SpeciesConstructor(_O_, %ArrayBuffer%).
1. Let _ctor_ be %ArrayBuffer%.
1. Let _new_ be ? Construct(_ctor_, « 𝔽(_newLen_) »).
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Suggested change
1. Let _ctor_ be %ArrayBuffer%.
1. Let _new_ be ? Construct(_ctor_, « 𝔽(_newLen_) »).
1. Let _new_ be ? Construct(%ArrayBuffer%, « 𝔽(_newLen_) »).

1. Perform ? RequireInternalSlot(_new_, [[ArrayBufferData]]).
1. If IsSharedArrayBuffer(_new_) is *true*, throw a *TypeError* exception.
Expand Down Expand Up @@ -44125,7 +44110,7 @@ <h1>SharedArrayBuffer.prototype.slice ( _start_, _end_ )</h1>
1. Else if _relativeEnd_ &lt; 0, let _final_ be max(_len_ + _relativeEnd_, 0).
1. Else, let _final_ be min(_relativeEnd_, _len_).
1. Let _newLen_ be max(_final_ - _first_, 0).
1. Let _ctor_ be ? SpeciesConstructor(_O_, %SharedArrayBuffer%).
1. Let _ctor_ be %SharedArrayBuffer%.
1. Let _new_ be ? Construct(_ctor_, « 𝔽(_newLen_) »).
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Suggested change
1. Let _ctor_ be %SharedArrayBuffer%.
1. Let _new_ be ? Construct(_ctor_, « 𝔽(_newLen_) »).
1. Let _new_ be ? Construct(%SharedArrayBuffer%, « 𝔽(_newLen_) »).

1. Perform ? RequireInternalSlot(_new_, [[ArrayBufferData]]).
1. If IsSharedArrayBuffer(_new_) is *false*, throw a *TypeError* exception.
Expand Down
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