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spec.html
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<!DOCTYPE html>
<meta charset="utf8" />
<pre class="metadata">
title: Change Array by copy
stage: 2
contributors: Robin Ricard, Ashley Claymore
</pre>
<emu-biblio href="biblio.json"></emu-biblio>
<emu-clause id="sec-indexed-collections">
<h1>Indexed Collections</h1>
<emu-clause id="sec-array-objects">
<h1>Array Objects</h1>
<emu-clause id="sec-properties-of-the-array-prototype-object">
<h1>Properties of the Array Prototype Object</h1>
<emu-clause id="sec-array.prototype.sort" oldids="sec-sortcompare">
<h1>Array.prototype.sort ( _comparefn_ )</h1>
<p>When the `sort` method is called, the following steps are taken:</p>
<emu-alg>
1. [id="step-array-sort-comparefn"] If _comparefn_ is not *undefined* and IsCallable(_comparefn_) is *false*, throw a *TypeError* exception.
1. Let _obj_ be ? ToObject(*this* value).
1. [id="step-array-sort-len"] Let _len_ be ? LengthOfArrayLike(_obj_).
1. Let _SortCompare_ be a new Abstract Closure with parameters (_x_, _y_) that captures _comparefn_ and performs the following steps when called:
1. <del>If _x_ and _y_ are both *undefined*, return *+0*<sub>𝔽</sub>.</del>
1. <del>If _x_ is *undefined*, return *1*<sub>𝔽</sub>.</del>
1. <del>If _y_ is *undefined*, return *-1*<sub>𝔽</sub>.</del>
1. <del>If _comparefn_ is not *undefined*, then</del>
1. <del>Let _v_ be ? ToNumber(? Call(_comparefn_, *undefined*, « _x_, _y_ »)).</del>
1. <del>If _v_ is *NaN*, return *+0*<sub>𝔽</sub>.</del>
1. <del>Return _v_.</del>
1. <del>[id="step-sortcompare-tostring-x"] Let _xString_ be ? ToString(_x_).</del>
1. <del>[id="step-sortcompare-tostring-y"] Let _yString_ be ? ToString(_y_).</del>
1. <del>Let _xSmaller_ be ! IsLessThan(_xString_, _yString_, *true*).</del>
1. <del>If _xSmaller_ is *true*, return *-1*<sub>𝔽</sub>.</del>
1. <del>Let _ySmaller_ be ! IsLessThan(_yString_, _xString_, *true*).</del>
1. <del>If _ySmaller_ is *true*, return *1*<sub>𝔽</sub>.</del>
1. <del>Return *+0*<sub>𝔽</sub>.</del>
1. <ins>Return ? CompareArrayElements(_x_, _y_, _comparefn_).</ins>
1. <del>Return ? SortIndexedProperties(_obj_, _len_, _SortCompare_).</del>
1. [id="step-array-sortindexedproperties"] <ins>Let _sortedList_ be ? SortIndexedProperties(_obj_, _len_, _SortCompare_, *true*).</ins>
1. <ins>Let _itemCount_ be the number of elements in _sortedList_.</ins>
1. <ins>Let _j_ be 0.</ins>
1. <ins>Repeat, while _j_ < _itemCount_,</ins>
1. <ins>Perform ? CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_j_)), _sortedList_[_j_]).</ins>
1. <ins>Set _j_ to _j_ + 1.</ins>
1. <ins>NOTE: The call to SortIndexedProperties in step <emu-xref href="#step-array-sortindexedproperties"></emu-xref> has the *skipHoles* parameter set to *true*. The remaining indexes are deleted to preserve the number of holes that were detected and excluded from the sort.</ins>
1. <ins>Repeat, while _j_ < _len_,</ins>
1. <ins>Perform ? DeletePropertyOrThrow(_obj_, ! ToString(𝔽(_j_))).</ins>
1. <ins>Set _j_ to _j_ + 1.</ins>
1. <ins>Return _obj_.</ins>
</emu-alg>
</emu-clause>
<emu-clause id="sec-comparearrayelements" type="abstract operation">
<h1>
CompareArrayElements(
_x_: unknown,
_y_: unknown,
_comparefn_: a function object or *undefined*
): either a normal completion containing a Number or an abrupt completion
</h1>
<dl class="header">
</dl>
<emu-alg>
1. If _x_ and _y_ are both *undefined*, return *+0*<sub>𝔽</sub>.
1. If _x_ is *undefined*, return *1*<sub>𝔽</sub>.
1. If _y_ is *undefined*, return *-1*<sub>𝔽</sub>.
1. If _comparefn_ is not *undefined*, then
1. Let _v_ be ? ToNumber(? Call(_comparefn_, *undefined*, « _x_, _y_ »)).
1. If _v_ is *NaN*, return *+0*<sub>𝔽</sub>.
1. Return _v_.
1. [id="step-sortcompare-tostring-x"] Let _xString_ be ? ToString(_x_).
1. [id="step-sortcompare-tostring-y"] Let _yString_ be ? ToString(_y_).
1. Let _xSmaller_ be ! IsLessThan(_xString_, _yString_, *true*).
1. If _xSmaller_ is *true*, return *-1*<sub>𝔽</sub>.
1. Let _ySmaller_ be ! IsLessThan(_yString_, _xString_, *true*).
1. If _ySmaller_ is *true*, return *1*<sub>𝔽</sub>.
1. Return *+0*<sub>𝔽</sub>.
</emu-alg>
</emu-clause>
<emu-clause id="sec-sortindexedproperties" type="abstract operation">
<h1>
SortIndexedProperties (
_obj_: an Object,
_len_: a non-negative integer,
_SortCompare_: an Abstract Closure with two parameters,
<ins>_skipHoles_: a Boolean</ins>
): either a normal completion containing <del>an Object</del><ins>a List</ins> or an abrupt completion
</h1>
<dl class="header">
</dl>
<emu-alg>
1. Let _items_ be a new empty List.
1. Let _k_ be 0.
1. Repeat, while _k_ < _len_,
1. Let _Pk_ be ! ToString(𝔽(_k_)).
1. <del>Let _kPresent_ be ? HasProperty(_obj_, _Pk_).</del>
1. <ins>If _skipHoles_ is *true*, then</ins>
1. <ins>Let _kRead_ be ? HasProperty(_obj_, _Pk_).</ins>
1. <ins>Else,</ins>
1. <ins>Let _kRead_ be *true*.</ins>
1. If <del>_kPresent_</del><ins>_kRead_</ins> is *true*, then
1. Let _kValue_ be ? Get(_obj_, _Pk_).
1. Append _kValue_ to _items_.
1. Set _k_ to _k_ + 1.
1. <del>Let _itemCount_ be the number of elements in _items_.</del>
1. [id="step-array-sort"] Sort _items_ using an implementation-defined sequence of calls to _SortCompare_. If any such call returns an abrupt completion, stop before performing any further calls to _SortCompare_ or steps in this algorithm and return that Completion Record.
1. <del>Let _j_ be 0.</del>
1. <del>Repeat, while _j_ < _itemCount_,</del>
1. <del>Perform ? Set(_obj_, ! ToString(𝔽(_j_)), _items_[_j_], *true*).</del>
1. <del>Set _j_ to _j_ + 1.</del>
1. <del>Repeat, while _j_ < _len_,</del>
1. <del>Perform ? DeletePropertyOrThrow(_obj_, ! ToString(𝔽(_j_))).</del>
1. <del>Set _j_ to _j_ + 1.</del>
1. <del>Return _obj_.</del>
1. <ins>Return _items_.</ins>
</emu-alg>
</emu-clause>
<emu-clause id="sec-array.prototype.toReversed">
<h1>Array.prototype.toReversed ( )</h1>
<p>When the *toReversed* method is called, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _len_ be ? LengthOfArrayLike(_O_).
1. Let _A_ be ? ArrayCreate(𝔽(_len_)).
1. Let _k_ be 0.
1. Repeat, while _k_ < _len_,
1. Let _from_ be ! ToString(𝔽(_len_ - _k_ - 1)).
1. Let _Pk_ be ! ToString(𝔽(_k_)).
1. Let _fromValue_ be ? Get(_O_, _from_).
1. Perform ! CreateDataPropertyOrThrow(_A_, _Pk_, _fromValue_).
1. Set _k_ to _k_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-array.prototype.toSorted">
<h1>Array.prototype.toSorted ( _comparefn_ )</h1>
<p>When the *toSorted* method is called, the following steps are taken:</p>
<emu-alg>
1. If _comparefn_ is not *undefined* and IsCallable(_comparefn_) is *false*, throw a *TypeError* exception.
1. Let _O_ be ? ToObject(*this* value).
1. Let _len_ be ? LengthOfArrayLike(_O_).
1. Let _A_ be ? ArrayCreate(𝔽(_len_)).
1. Let _SortCompare_ be a new Abstract Closure with parameters (_x_, _y_) that captures _comparefn_ and performs the following steps when called:
1. Return ? CompareArrayElements(_x_, _y_, _comparefn_).
1. Let _sortedList_ be ? SortIndexedProperties(_obj_, _len_, _SortCompare_, *false*).
1. Let _j_ be 0.
1. Repeat, while _j_ < _len_,
1. Perform ! CreateDataPropertyOrThrow(_A_, ! ToString(𝔽(_j_)), _sortedList_[_j_]).
1. Set _j_ to _j_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-array.prototype.toSpliced">
<h1>Array.prototype.toSpliced ( _start_, _deleteCount_, ..._items_ )</h1>
<p>When the *toSpliced* method is called, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _len_ be ? LengthOfArrayLike(_O_).
1. Let _relativeStart_ be ? ToIntegerOrInfinity(_start_).
1. If _relativeStart_ is -∞, let _actualStart_ be 0.
1. Else if _relativeStart_ < 0, let _actualStart_ be max(_len_ + _relativeStart_, 0).
1. Else, let _actualStart_ be min(_relativeStart_, _len_).
1. Let _insertCount_ be the number of elements in _items_.
1. If _start_ is not present, then
1. Let _actualDeleteCount_ be 0.
1. Else if _deleteCount_ is not present, then
1. Let _actualDeleteCount_ be _len_ - _actualStart_.
1. Else,
1. Let _dc_ be ? ToIntegerOrInfinity(_deleteCount_).
1. Let _actualDeleteCount_ be the result of clamping _dc_ between 0 and _len_ - _actualStart_.
1. Let _newLen_ be _len_ + _insertCount_ - _actualDeleteCount_.
1. If _newLen_ > 2<sup>53</sup> - 1, throw a *TypeError* exception.
1. Let _A_ be ? ArrayCreate(𝔽(_newLen_)).
1. Let _i_ be 0.
1. Let _r_ be _actualStart_ + _actualDeleteCount_.
1. Repeat, while _i_ < _actualStart_,
1. Let _Pi_ be ! ToString(𝔽(_i_)).
1. Let _iValue_ be ? Get(_O_, _Pi_).
1. Perform ! CreateDataPropertyOrThrow(_A_, _Pi_, _iValue_).
1. Set _i_ to _i_ + 1.
1. For each element _E_ of _items_, do
1. Let _Pi_ be ! ToString(𝔽(_i_)).
1. Perform ! CreateDataPropertyOrThrow(_A_, _Pi_, _E_).
1. Set _i_ to _i_ + 1.
1. Repeat, while _i_ < _newLen_,
1. Let _Pi_ be ! ToString(𝔽(_i_)).
1. Let _from_ be ! ToString(𝔽(_r_)).
1. Let _fromValue_ be ? Get(_O_, _from_).
1. Perform ! CreateDataPropertyOrThrow(_A_, _Pi_, _fromValue_).
1. Set _i_ to _i_ + 1.
1. Set _r_ to _r_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-array.prototype.with">
<h1>Array.prototype.with ( _index_, _value_ )</h1>
<p>When the *with* method is called, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be ? ToObject(*this* value).
1. Let _len_ be ? LengthOfArrayLike(_O_).
1. Let _relativeIndex_ be ? ToIntegerOrInfinity(_index_).
1. If _relativeIndex_ ≥ 0, let _actualIndex_ be _relativeIndex_.
1. Else, let _actualIndex_ be _len_ + _relativeIndex_.
1. If _actualIndex_ ≥ _len_ or _actualIndex_ < 0, throw a *RangeError* exception.
1. Let _A_ be ? ArrayCreate(𝔽(_len_)).
1. Let _k_ be 0.
1. Repeat, while _k_ < _len_,
1. Let _Pk_ be ! ToString(𝔽(_k_)).
1. If _k_ is _actualIndex_, let _fromValue_ be _value_.
1. Else, let _fromValue_ be ? Get(_O_, _Pk_).
1. Perform ! CreateDataPropertyOrThrow(_A_, _Pk_, _fromValue_).
1. Set _k_ to _k_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-array.prototype-@@unscopables">
<h1>Array.prototype [ @@unscopables ]</h1>
<p>The initial value of the @@unscopables data property is an object created by the following steps:</p>
<emu-alg>
1. Let _unscopableList_ be ! OrdinaryObjectCreate(*null*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"at"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"copyWithin"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"entries"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"fill"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"find"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"findIndex"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"flat"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"flatMap"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"includes"*, *true*).
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"keys"*, *true*).
1. <ins>Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"toReversed"*, *true*).</ins>
1. <ins>Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"toSorted"*, *true*).</ins>
1. <ins>Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"toSpliced"*, *true*).</ins>
1. Perform ! CreateDataPropertyOrThrow(_unscopableList_, *"values"*, *true*).
1. Return _unscopableList_.
</emu-alg>
<p>This property has the attributes { [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }.</p>
<emu-note>
<p>The reason that *"with"* is not included in the _unscopableList_ is because it is already a <emu-xref href="#sec-keywords-and-reserved-words">reserved word</emu-xref>.</p>
</emu-note>
</emu-clause>
</emu-clause>
</emu-clause>
<emu-clause id="sec-typedarray-objects">
<h1>TypedArray Objects</h1>
<emu-clause id="sec-abstract-operations-for-typedarray-objects">
<h1>Abstract Operations for TypedArray Objects</h1>
<emu-clause id="typedarray-create-same-type" type="abstract operation">
<h1>
TypedArrayCreateSameType (
_exemplar_: a TypedArray,
_argumentList_: unknown,
)
</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 TypedArraySpeciesCreate, which can construct custom TypedArray subclasses through the use of @@species, this operation always uses one of the built-in TypedArray constructors.</dd>
</dl>
<emu-alg>
1. Assert: _exemplar_ is an Object that has [[TypedArrayName]] and [[ContentType]] internal slots.
1. Let _constructor_ be the intrinsic object listed in column one of <emu-xref href="#table-the-typedarray-constructors"></emu-xref> for _exemplar_.[[TypedArrayName]].
1. Let _result_ be ? TypedArrayCreate(_constructor_, _argumentList_).
1. Assert: _result_ has [[TypedArrayName]] and [[ContentType]] internal slots.
1. Assert: _result_.[[ContentType]] is _exemplar_.[[ContentType]].
1. Return _result_.
</emu-alg>
</emu-clause>
</emu-clause>
<emu-clause id="sec-%typedarray%-intrinsic-object">
<h1>The %TypedArray% Intrinsic Object</h1>
<emu-clause id="sec-properties-of-the-%typedarrayprototype%-object">
<h1>Properties of the %TypedArray% Prototype Object</h1>
<emu-clause id="sec-%typedarray%.prototype.sort" oldids="sec-typedarraysortcompare">
<h1>%TypedArray%.prototype.sort ( _comparefn_ )</h1>
<p>The following steps are performed:</p>
<emu-alg>
1. If _comparefn_ is not *undefined* and IsCallable(_comparefn_) is *false*, throw a *TypeError* exception.
1. Let _obj_ be the *this* value.
1. Perform ? ValidateTypedArray(_obj_).
1. Let _buffer_ be _obj_.[[ViewedArrayBuffer]].
1. Let _len_ be _obj_.[[ArrayLength]].
1. NOTE: The following closure performs a numeric comparison rather than the string comparison used in <emu-xref href="#sec-array.prototype.sort"></emu-xref>.
1. Let _SortCompare_ be a new Abstract Closure with parameters (_x_, _y_) that captures _comparefn_ and _buffer_ and performs the following steps when called:
1. <del>Assert: Both Type(_x_) and Type(_y_) are Number or both are BigInt.</del>
1. <del>If _comparefn_ is not *undefined*, then</del>
1. <del>Let _v_ be ? ToNumber(? Call(_comparefn_, *undefined*, « _x_, _y_ »)).</del>
1. <del>If IsDetachedBuffer(_buffer_) is *true*, throw a *TypeError* exception.</del>
1. <del>If _v_ is *NaN*, return *+0*<sub>𝔽</sub>.</del>
1. <del>Return _v_.</del>
1. <del>If _x_ and _y_ are both *NaN*, return *+0*<sub>𝔽</sub>.</del>
1. <del>If _x_ is *NaN*, return *1*<sub>𝔽</sub>.</del>
1. <del>If _y_ is *NaN*, return *-1*<sub>𝔽</sub>.</del>
1. <del>If _x_ < _y_, return *-1*<sub>𝔽</sub>.</del>
1. <del>If _x_ > _y_, return *1*<sub>𝔽</sub>.</del>
1. <del>If _x_ is *-0*<sub>𝔽</sub> and _y_ is *+0*<sub>𝔽</sub>, return *-1*<sub>𝔽</sub>.</del>
1. <del>If _x_ is *+0*<sub>𝔽</sub> and _y_ is *-0*<sub>𝔽</sub>, return *1*<sub>𝔽</sub>.</del>
1. <del>Return *+0*<sub>𝔽</sub>.</del>
1. <ins>Return ? CompareTypedArrayElements(_x_, _y_, _comparefn_, _buffer_).</ins>
1. <del>Return ? SortIndexedProperties(_obj_, _len_, _SortCompare_).</del>
1. <ins>Let _sortedList_ be ? SortIndexedProperties(_obj_, _len_, _SortCompare_, *false*).</ins>
1. <ins>Let _j_ be 0.</ins>
1. <ins>Repeat, while _j_ < _len_,</ins>
1. <ins>Perform ! Set(_obj_, ! ToString(𝔽(_j_)), _sortedList_[_j_], *true*).</ins>
1. <ins>Set _j_ to _j_ + 1.</ins>
1. <ins>Return _obj_.</ins>
</emu-alg>
</emu-clause>
<emu-clause id="sec-comparetypedarrayelements" type="abstract operation">
<h1>
CompareTypedArrayElements(
_x_: unknown,
_y_: unknown,
_comparefn_: a function object or *undefined*,
_buffer_: An ArrayBuffer
): either a normal completion containing a Number or an abrupt completion
</h1>
<dl class="header">
</dl>
<emu-alg>
1. Assert: Both Type(_x_) and Type(_y_) are Number or both are BigInt.
1. If _comparefn_ is not *undefined*, then
1. Let _v_ be ? ToNumber(? Call(_comparefn_, *undefined*, « _x_, _y_ »)).
1. If IsDetachedBuffer(_buffer_) is *true*, throw a *TypeError* exception.
1. If _v_ is *NaN*, return *+0*<sub>𝔽</sub>.
1. Return _v_.
1. If _x_ and _y_ are both *NaN*, return *+0*<sub>𝔽</sub>.
1. If _x_ is *NaN*, return *1*<sub>𝔽</sub>.
1. If _y_ is *NaN*, return *-1*<sub>𝔽</sub>.
1. If _x_ < _y_, return *-1*<sub>𝔽</sub>.
1. If _x_ > _y_, return *1*<sub>𝔽</sub>.
1. If _x_ is *-0*<sub>𝔽</sub> and _y_ is *+0*<sub>𝔽</sub>, return *-1*<sub>𝔽</sub>.
1. If _x_ is *+0*<sub>𝔽</sub> and _y_ is *-0*<sub>𝔽</sub>, return *1*<sub>𝔽</sub>.
1. Return *+0*<sub>𝔽</sub>.
</emu-alg>
<emu-note>
This performs a numeric comparison rather than the string comparison used in <emu-xref href="#sec-comparearrayelements"></emu-xref>.
</emu-note>
</emu-clause>
<emu-clause id="sec-%typedarray%.prototype.toReversed">
<h1>%TypedArray%.prototype.toReversed ( )</h1>
<p>When the *toReversed* method is called, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be the *this* value.
1. Perform ? ValidateTypedArray(_O_).
1. Let _length_ be _O_.[[ArrayLength]].
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_length_) »).
1. Let _k_ be 0.
1. Repeat, while _k_ < _length_,
1. Let _from_ be ! ToString(𝔽(_length_ - _k_ - 1)).
1. Let _Pk_ be ! ToString(𝔽(_k_)).
1. Let _fromValue_ be ! Get(_O_, _from_).
1. Perform ! Set(_A_, _Pk_, _kValue_, *true*).
1. Set _k_ to _k_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-%typedarray%.prototype.toSorted">
<h1>%TypedArray%.prototype.toSorted ( _comparefn_ )</h1>
<p>When the *toSorted* method is called, the following steps are taken:</p>
<emu-alg>
1. If _comparefn_ is not *undefined* and IsCallable(_comparefn_) is *false*, throw a *TypeError* exception.
1. Let _O_ be the *this* value.
1. Perform ? ValidateTypedArray(_O_).
1. Let _buffer_ be _obj_.[[ViewedArrayBuffer]].
1. Let _len_ be _O_.[[ArrayLength]].
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_len_) »).
1. NOTE: The following closure performs a numeric comparison rather than the string comparison used in <emu-xref href="#sec-array.prototype.toSorted"></emu-xref>.
1. Let _SortCompare_ be a new Abstract Closure with parameters (_x_, _y_) that captures _comparefn_ and _buffer_ and performs the following steps when called:
1. Return ? CompareTypedArrayElements(_x_, _y_, _comparefn_, _buffer_).
1. Let _sortedList_ be ? SortIndexedProperties(_obj_, _len_, _SortCompare_, *false*).
1. Let _j_ be 0.
1. Repeat, while _j_ < _len_,
1. Perform ! Set(_A_, ! ToString(𝔽(_j_)), _sortedList_[_j_], *true*).
1. Set _j_ to _j_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
<emu-clause id="sec-%typedarray%.prototype.toSpliced">
<h1>%TypedArray%.prototype.toSpliced ( _start_, _deleteCount_, ..._items_ )</h1>
<p>When the *toSpliced* method is called, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be the *this* value.
1. Perform ? ValidateTypedArray(_O_).
1. Let _len_ be _O_.[[ArrayLength]].
1. Let _relativeStart_ be ? ToIntegerOrInfinity(_start_).
1. If _relativeStart_ is -∞, let _actualStart_ be 0.
1. Else if _relativeStart_ < 0, let _actualStart_ be max(_len_ + _relativeStart_, 0).
1. Else, let _actualStart_ be min(_relativeStart_, _len_).
1. Let _insertCount_ be the number of elements in _items_.
1. If _start_ is not present, then
1. Let _actualDeleteCount_ be 0.
1. Else if _deleteCount_ is not present, then
1. Let _actualDeleteCount_ be _len_ - _actualStart_.
1. Else,
1. Let _dc_ be ? ToIntegerOrInfinity(_deleteCount_).
1. Let _actualDeleteCount_ be the result of clamping _dc_ between 0 and _len_ - _actualStart_.
1. Let _newLen_ be _len_ + _insertCount_ - _actualDeleteCount_.
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_newLen_) »).
1. Let _i_ be 0.
1. Let _r_ be _actualStart_ + _actualDeleteCount_.
1. Repeat, while _i_ < _actualStart_,
1. Let _Pi_ be ! ToString(𝔽(_i_)).
1. Let _iValue_ be ! Get(_src_, _Pi_).
1. Perform ! Set(_target_, _Pi_, _iValue_, *true*).
1. Set _i_ to _i_ + 1.
1. For each element _E_ of _items_, do
1. Let _Pi_ be ! ToString(𝔽(_i_)).
1. [id="step-typedarray-tospliced-set"] Perform ? Set(_A_, _Pi_, _E_, *true*).
1. Set _i_ to _i_ + 1.
1. Repeat, while _r_ < _newLen_,
1. Let _Pi_ be ! ToString(𝔽(_i_)).
1. Let _from_ be ! ToString(𝔽(_r_)).
1. Let _fromValue_ be ! Get(_O_, _from_).
1. Perform ! Set(_A_, _Pi_, _fromValue_, *true*).
1. Set _i_ to _i_ + 1.
1. Set _r_ to _r_ + 1.
1. Return _A_.
</emu-alg>
<emu-note>
Step <emu-xref href="#step-typedarray-tospliced-set"></emu-xref> may return an abrupt completion because _E_ is a value of any ECMAScript language type and is passed to ToBigInt or ToNumber.
</emu-note>
</emu-clause>
<emu-clause id="sec-%typedarray%.prototype.with">
<h1>%TypedArray%.prototype.with ( _index_, _value_ )</h1>
<p>When the *with* method is called, the following steps are taken:</p>
<emu-alg>
1. Let _O_ be the *this* value.
1. Perform ? ValidateTypedArray(_O_).
1. Let _len_ be _O_.[[ArrayLength]].
1. Let _relativeIndex_ be ? ToIntegerOrInfinity(_index_).
1. If _relativeIndex_ ≥ 0, let _actualIndex_ be _relativeIndex_.
1. Else, let _actualIndex_ be _len_ + _relativeIndex_.
1. If _O_.[[ContentType]] is ~BigInt~, set _value_ to ? ToBigInt(_value_).
1. Else, set _value_ to ? ToNumber(_value_).
1. If ! IsValidIntegerIndex(_O_, 𝔽(_actualIndex_)) is *false*, throw a *RangeError* exception.
1. Let _A_ be ? TypedArrayCreateSameType(_O_, « 𝔽(_len_) »).
1. Let _k_ be 0.
1. Repeat, while _k_ < _len_,
1. Let _Pk_ be ! ToString(𝔽(_k_)).
1. If _k_ is _actualIndex_, let _fromValue_ be _value_.
1. Else, let _fromValue_ be ! Get(_O_, _Pk_).
1. Perform ! Set(_A_, _Pk_, _fromValue_, *true*).
1. Set _k_ to _k_ + 1.
1. Return _A_.
</emu-alg>
</emu-clause>
</emu-clause>
</emu-clause>
</emu-clause>
</emu-clause>