ECMAScript® 2024 Language Specification

Draft ECMA-262 / February 15, 2024

23.2 TypedArray Objects

A TypedArray presents an array-like view of an underlying binary data buffer (25.1). A TypedArray element type is the underlying binary scalar data type that all elements of a TypedArray instance have. There is a distinct TypedArray constructor, listed in Table 71, for each of the supported element types. Each constructor in Table 71 has a corresponding distinct prototype object.

Table 71: The TypedArray Constructors
Constructor Name and Intrinsic Element Type Element Size Conversion Operation Description
Int8Array
%Int8Array% 		int8 1 ToInt8 8-bit two's complement signed integer
Uint8Array
%Uint8Array% 		uint8 1 ToUint8 8-bit unsigned integer
Uint8ClampedArray
%Uint8ClampedArray% 		uint8clamped 1 ToUint8Clamp 8-bit unsigned integer (clamped conversion)
Int16Array
%Int16Array% 		int16 2 ToInt16 16-bit two's complement signed integer
Uint16Array
%Uint16Array% 		uint16 2 ToUint16 16-bit unsigned integer
Int32Array
%Int32Array% 		int32 4 ToInt32 32-bit two's complement signed integer
Uint32Array
%Uint32Array% 		uint32 4 ToUint32 32-bit unsigned integer
BigInt64Array
%BigInt64Array% 		bigint64 8 ToBigInt64 64-bit two's complement signed integer
BigUint64Array
%BigUint64Array% 		biguint64 8 ToBigUint64 64-bit unsigned integer
Float32Array
%Float32Array% 		float32 4 32-bit IEEE floating point
Float64Array
%Float64Array% 		float64 8 64-bit IEEE floating point

In the definitions below, references to TypedArray should be replaced with the appropriate constructor name from the above table.

23.2.1 The %TypedArray% Intrinsic Object

The %TypedArray% intrinsic object:

  • is a constructor function object that all of the TypedArray constructor objects inherit from.
  • along with its corresponding prototype object, provides common properties that are inherited by all TypedArray constructors and their instances.
  • does not have a global name or appear as a property of the global object.
  • acts as the abstract superclass of the various TypedArray constructors.
  • will throw an error when invoked, because it is an abstract class constructor. The TypedArray constructors do not perform a super call to it.

23.2.1.1 %TypedArray% ( )

This function performs the following steps when called:

  1. Throw a TypeError exception.

The "length" property of this function is +0𝔽.

23.2.2 Properties of the %TypedArray% Intrinsic Object

The %TypedArray% intrinsic object:

  • has a [[Prototype]] internal slot whose value is %Function.prototype%.
  • has a "name" property whose value is "TypedArray".
  • has the following properties:

23.2.2.1 %TypedArray%.from ( source [ , mapfn [ , thisArg ] ] )

This method performs the following steps when called:

  1. Let C be the this value.
  2. If IsConstructor(C) is false, throw a TypeError exception.
  3. If mapfn is undefined, then
    1. Let mapping be false.
  4. Else,
    1. If IsCallable(mapfn) is false, throw a TypeError exception.
    2. Let mapping be true.
  5. Let usingIterator be ? GetMethod(source, @@iterator).
  6. If usingIterator is not undefined, then
    1. Let values be ? IteratorToList(? GetIteratorFromMethod(source, usingIterator)).
    2. Let len be the number of elements in values.
    3. Let targetObj be ? TypedArrayCreateFromConstructor(C, « 𝔽(len) »).
    4. Let k be 0.
    5. Repeat, while k < len,
      1. Let Pk be ! ToString(𝔽(k)).
      2. Let kValue be the first element of values.
      3. Remove the first element from values.
      4. If mapping is true, then
        1. Let mappedValue be ? Call(mapfn, thisArg, « kValue, 𝔽(k) »).
      5. Else,
        1. Let mappedValue be kValue.
      6. Perform ? Set(targetObj, Pk, mappedValue, true).
      7. Set k to k + 1.
    6. Assert: values is now an empty List.
    7. Return targetObj.
  7. NOTE: source is not an Iterable so assume it is already an array-like object.
  8. Let arrayLike be ! ToObject(source).
  9. Let len be ? LengthOfArrayLike(arrayLike).
  10. Let targetObj be ? TypedArrayCreateFromConstructor(C, « 𝔽(len) »).
  11. Let k be 0.
  12. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ? Get(arrayLike, Pk).
    3. If mapping is true, then
      1. Let mappedValue be ? Call(mapfn, thisArg, « kValue, 𝔽(k) »).
    4. Else,
      1. Let mappedValue be kValue.
    5. Perform ? Set(targetObj, Pk, mappedValue, true).
    6. Set k to k + 1.
  13. Return targetObj.

23.2.2.2 %TypedArray%.of ( ...items )

This method performs the following steps when called:

  1. Let len be the number of elements in items.
  2. Let C be the this value.
  3. If IsConstructor(C) is false, throw a TypeError exception.
  4. Let newObj be ? TypedArrayCreateFromConstructor(C, « 𝔽(len) »).
  5. Let k be 0.
  6. Repeat, while k < len,
    1. Let kValue be items[k].
    2. Let Pk be ! ToString(𝔽(k)).
    3. Perform ? Set(newObj, Pk, kValue, true).
    4. Set k to k + 1.
  7. Return newObj.

23.2.2.3 %TypedArray%.prototype

The initial value of %TypedArray%.prototype is the %TypedArray% prototype object.

This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

23.2.2.4 get %TypedArray% [ @@species ]

%TypedArray%[@@species] is an accessor property whose set accessor function is undefined. Its get accessor function performs the following steps when called:

  1. Return the this value.

The value of the "name" property of this function is "get [Symbol.species]".

Note

%TypedArray.prototype% methods normally use their this value's constructor to create a derived object. However, a subclass constructor may over-ride that default behaviour by redefining its @@species property.

23.2.3 Properties of the %TypedArray% Prototype Object

The %TypedArray% prototype object:

  • has a [[Prototype]] internal slot whose value is %Object.prototype%.
  • is %TypedArray.prototype%.
  • is an ordinary object.
  • does not have a [[ViewedArrayBuffer]] or any other of the internal slots that are specific to TypedArray instance objects.

23.2.3.1 %TypedArray%.prototype.at ( index )

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let relativeIndex be ? ToIntegerOrInfinity(index).
  5. If relativeIndex ≥ 0, then
    1. Let k be relativeIndex.
  6. Else,
    1. Let k be len + relativeIndex.
  7. If k < 0 or k ≥ len, return undefined.
  8. Return ! Get(O, ! ToString(𝔽(k))).

23.2.3.2 get %TypedArray%.prototype.buffer

%TypedArray%.prototype.buffer is an accessor property whose set accessor function is undefined. Its get accessor function performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? RequireInternalSlot(O, [[TypedArrayName]]).
  3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
  4. Let buffer be O.[[ViewedArrayBuffer]].
  5. Return buffer.

23.2.3.3 get %TypedArray%.prototype.byteLength

%TypedArray%.prototype.byteLength is an accessor property whose set accessor function is undefined. Its get accessor function performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? RequireInternalSlot(O, [[TypedArrayName]]).
  3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
  4. Let taRecord be MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
  5. Let size be TypedArrayByteLength(taRecord).
  6. Return 𝔽(size).

23.2.3.4 get %TypedArray%.prototype.byteOffset

%TypedArray%.prototype.byteOffset is an accessor property whose set accessor function is undefined. Its get accessor function performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? RequireInternalSlot(O, [[TypedArrayName]]).
  3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
  4. Let taRecord be MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
  5. If IsTypedArrayOutOfBounds(taRecord) is true, return +0𝔽.
  6. Let offset be O.[[ByteOffset]].
  7. Return 𝔽(offset).

23.2.3.5 %TypedArray%.prototype.constructor

The initial value of %TypedArray%.prototype.constructor is %TypedArray%.

23.2.3.6 %TypedArray%.prototype.copyWithin ( target, start [ , end ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.copyWithin as defined in 23.1.3.4.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let relativeTarget be ? ToIntegerOrInfinity(target).
  5. If relativeTarget = -∞, let targetIndex be 0.
  6. Else if relativeTarget < 0, let targetIndex be max(len + relativeTarget, 0).
  7. Else, let targetIndex be min(relativeTarget, len).
  8. Let relativeStart be ? ToIntegerOrInfinity(start).
  9. If relativeStart = -∞, let startIndex be 0.
  10. Else if relativeStart < 0, let startIndex be max(len + relativeStart, 0).
  11. Else, let startIndex be min(relativeStart, len).
  12. If end is undefined, let relativeEnd be len; else let relativeEnd be ? ToIntegerOrInfinity(end).
  13. If relativeEnd = -∞, let endIndex be 0.
  14. Else if relativeEnd < 0, let endIndex be max(len + relativeEnd, 0).
  15. Else, let endIndex be min(relativeEnd, len).
  16. Let count be min(endIndex - startIndex, len - targetIndex).
  17. If count > 0, then
    1. NOTE: The copying must be performed in a manner that preserves the bit-level encoding of the source data.
    2. Let buffer be O.[[ViewedArrayBuffer]].
    3. Set taRecord to MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
    4. If IsTypedArrayOutOfBounds(taRecord) is true, throw a TypeError exception.
    5. Set len to TypedArrayLength(taRecord).
    6. Let elementSize be TypedArrayElementSize(O).
    7. Let byteOffset be O.[[ByteOffset]].
    8. Let bufferByteLimit be (len × elementSize) + byteOffset.
    9. Let toByteIndex be (targetIndex × elementSize) + byteOffset.
    10. Let fromByteIndex be (startIndex × elementSize) + byteOffset.
    11. Let countBytes be count × elementSize.
    12. If fromByteIndex < toByteIndex and toByteIndex < fromByteIndex + countBytes, then
      1. Let direction be -1.
      2. Set fromByteIndex to fromByteIndex + countBytes - 1.
      3. Set toByteIndex to toByteIndex + countBytes - 1.
    13. Else,
      1. Let direction be 1.
    14. Repeat, while countBytes > 0,
      1. If fromByteIndex < bufferByteLimit and toByteIndex < bufferByteLimit, then
        1. Let value be GetValueFromBuffer(buffer, fromByteIndex, uint8, true, unordered).
        2. Perform SetValueInBuffer(buffer, toByteIndex, uint8, value, true, unordered).
        3. Set fromByteIndex to fromByteIndex + direction.
        4. Set toByteIndex to toByteIndex + direction.
        5. Set countBytes to countBytes - 1.
      2. Else,
        1. Set countBytes to 0.
  18. Return O.

23.2.3.7 %TypedArray%.prototype.entries ( )

This method performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? ValidateTypedArray(O, seq-cst).
  3. Return CreateArrayIterator(O, key+value).

23.2.3.8 %TypedArray%.prototype.every ( callbackfn [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.every as defined in 23.1.3.6.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. Let k be 0.
  6. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Let testResult be ToBoolean(? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »)).
    4. If testResult is false, return false.
    5. Set k to k + 1.
  7. Return true.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.9 %TypedArray%.prototype.fill ( value [ , start [ , end ] ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.fill as defined in 23.1.3.7.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If O.[[ContentType]] is bigint, set value to ? ToBigInt(value).
  5. Otherwise, set value to ? ToNumber(value).
  6. Let relativeStart be ? ToIntegerOrInfinity(start).
  7. If relativeStart = -∞, let startIndex be 0.
  8. Else if relativeStart < 0, let startIndex be max(len + relativeStart, 0).
  9. Else, let startIndex be min(relativeStart, len).
  10. If end is undefined, let relativeEnd be len; else let relativeEnd be ? ToIntegerOrInfinity(end).
  11. If relativeEnd = -∞, let endIndex be 0.
  12. Else if relativeEnd < 0, let endIndex be max(len + relativeEnd, 0).
  13. Else, let endIndex be min(relativeEnd, len).
  14. Set taRecord to MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
  15. If IsTypedArrayOutOfBounds(taRecord) is true, throw a TypeError exception.
  16. Set len to TypedArrayLength(taRecord).
  17. Set endIndex to min(endIndex, len).
  18. Let k be startIndex.
  19. Repeat, while k < endIndex,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Perform ! Set(O, Pk, value, true).
    3. Set k to k + 1.
  20. Return O.

23.2.3.10 %TypedArray%.prototype.filter ( callbackfn [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.filter as defined in 23.1.3.8.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. Let kept be a new empty List.
  6. Let captured be 0.
  7. Let k be 0.
  8. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Let selected be ToBoolean(? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »)).
    4. If selected is true, then
      1. Append kValue to kept.
      2. Set captured to captured + 1.
    5. Set k to k + 1.
  9. Let A be ? TypedArraySpeciesCreate(O, « 𝔽(captured) »).
  10. Let n be 0.
  11. For each element e of kept, do
    1. Perform ! Set(A, ! ToString(𝔽(n)), e, true).
    2. Set n to n + 1.
  12. Return A.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.11 %TypedArray%.prototype.find ( predicate [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.find as defined in 23.1.3.9.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let findRec be ? FindViaPredicate(O, len, ascending, predicate, thisArg).
  5. Return findRec.[[Value]].

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.12 %TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.findIndex as defined in 23.1.3.10.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let findRec be ? FindViaPredicate(O, len, ascending, predicate, thisArg).
  5. Return findRec.[[Index]].

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.13 %TypedArray%.prototype.findLast ( predicate [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.findLast as defined in 23.1.3.11.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let findRec be ? FindViaPredicate(O, len, descending, predicate, thisArg).
  5. Return findRec.[[Value]].

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.14 %TypedArray%.prototype.findLastIndex ( predicate [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.findLastIndex as defined in 23.1.3.12.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let findRec be ? FindViaPredicate(O, len, descending, predicate, thisArg).
  5. Return findRec.[[Index]].

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.15 %TypedArray%.prototype.forEach ( callbackfn [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.forEach as defined in 23.1.3.15.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. Let k be 0.
  6. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Perform ? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »).
    4. Set k to k + 1.
  7. Return undefined.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.16 %TypedArray%.prototype.includes ( searchElement [ , fromIndex ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.includes as defined in 23.1.3.16.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If len = 0, return false.
  5. Let n be ? ToIntegerOrInfinity(fromIndex).
  6. Assert: If fromIndex is undefined, then n is 0.
  7. If n = +∞, return false.
  8. Else if n = -∞, set n to 0.
  9. If n ≥ 0, then
    1. Let k be n.
  10. Else,
    1. Let k be len + n.
    2. If k < 0, set k to 0.
  11. Repeat, while k < len,
    1. Let elementK be ! Get(O, ! ToString(𝔽(k))).
    2. If SameValueZero(searchElement, elementK) is true, return true.
    3. Set k to k + 1.
  12. Return false.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.17 %TypedArray%.prototype.indexOf ( searchElement [ , fromIndex ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.indexOf as defined in 23.1.3.17.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If len = 0, return -1𝔽.
  5. Let n be ? ToIntegerOrInfinity(fromIndex).
  6. Assert: If fromIndex is undefined, then n is 0.
  7. If n = +∞, return -1𝔽.
  8. Else if n = -∞, set n to 0.
  9. If n ≥ 0, then
    1. Let k be n.
  10. Else,
    1. Let k be len + n.
    2. If k < 0, set k to 0.
  11. Repeat, while k < len,
    1. Let kPresent be ! HasProperty(O, ! ToString(𝔽(k))).
    2. If kPresent is true, then
      1. Let elementK be ! Get(O, ! ToString(𝔽(k))).
      2. If IsStrictlyEqual(searchElement, elementK) is true, return 𝔽(k).
    3. Set k to k + 1.
  12. Return -1𝔽.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.18 %TypedArray%.prototype.join ( separator )

The interpretation and use of the arguments of this method are the same as for Array.prototype.join as defined in 23.1.3.18.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If separator is undefined, let sep be ",".
  5. Else, let sep be ? ToString(separator).
  6. Let R be the empty String.
  7. Let k be 0.
  8. Repeat, while k < len,
    1. If k > 0, set R to the string-concatenation of R and sep.
    2. Let element be ! Get(O, ! ToString(𝔽(k))).
    3. If element is undefined, let next be the empty String; otherwise, let next be ! ToString(element).
    4. Set R to the string-concatenation of R and next.
    5. Set k to k + 1.
  9. Return R.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.19 %TypedArray%.prototype.keys ( )

This method performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? ValidateTypedArray(O, seq-cst).
  3. Return CreateArrayIterator(O, key).

23.2.3.20 %TypedArray%.prototype.lastIndexOf ( searchElement [ , fromIndex ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.lastIndexOf as defined in 23.1.3.20.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If len = 0, return -1𝔽.
  5. If fromIndex is present, let n be ? ToIntegerOrInfinity(fromIndex); else let n be len - 1.
  6. If n = -∞, return -1𝔽.
  7. If n ≥ 0, then
    1. Let k be min(n, len - 1).
  8. Else,
    1. Let k be len + n.
  9. Repeat, while k ≥ 0,
    1. Let kPresent be ! HasProperty(O, ! ToString(𝔽(k))).
    2. If kPresent is true, then
      1. Let elementK be ! Get(O, ! ToString(𝔽(k))).
      2. If IsStrictlyEqual(searchElement, elementK) is true, return 𝔽(k).
    3. Set k to k - 1.
  10. Return -1𝔽.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.21 get %TypedArray%.prototype.length

%TypedArray%.prototype.length is an accessor property whose set accessor function is undefined. Its get accessor function performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? RequireInternalSlot(O, [[TypedArrayName]]).
  3. Assert: O has [[ViewedArrayBuffer]] and [[ArrayLength]] internal slots.
  4. Let taRecord be MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
  5. If IsTypedArrayOutOfBounds(taRecord) is true, return +0𝔽.
  6. Let length be TypedArrayLength(taRecord).
  7. Return 𝔽(length).

This function is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.22 %TypedArray%.prototype.map ( callbackfn [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.map as defined in 23.1.3.21.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. Let A be ? TypedArraySpeciesCreate(O, « 𝔽(len) »).
  6. Let k be 0.
  7. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Let mappedValue be ? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »).
    4. Perform ? Set(A, Pk, mappedValue, true).
    5. Set k to k + 1.
  8. Return A.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.23 %TypedArray%.prototype.reduce ( callbackfn [ , initialValue ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.reduce as defined in 23.1.3.24.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. If len = 0 and initialValue is not present, throw a TypeError exception.
  6. Let k be 0.
  7. Let accumulator be undefined.
  8. If initialValue is present, then
    1. Set accumulator to initialValue.
  9. Else,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Set accumulator to ! Get(O, Pk).
    3. Set k to k + 1.
  10. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Set accumulator to ? Call(callbackfn, undefined, « accumulator, kValue, 𝔽(k), O »).
    4. Set k to k + 1.
  11. Return accumulator.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.24 %TypedArray%.prototype.reduceRight ( callbackfn [ , initialValue ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.reduceRight as defined in 23.1.3.25.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. If len = 0 and initialValue is not present, throw a TypeError exception.
  6. Let k be len - 1.
  7. Let accumulator be undefined.
  8. If initialValue is present, then
    1. Set accumulator to initialValue.
  9. Else,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Set accumulator to ! Get(O, Pk).
    3. Set k to k - 1.
  10. Repeat, while k ≥ 0,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Set accumulator to ? Call(callbackfn, undefined, « accumulator, kValue, 𝔽(k), O »).
    4. Set k to k - 1.
  11. Return accumulator.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.25 %TypedArray%.prototype.reverse ( )

The interpretation and use of the arguments of this method are the same as for Array.prototype.reverse as defined in 23.1.3.26.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let middle be floor(len / 2).
  5. Let lower be 0.
  6. Repeat, while lower ≠ middle,
    1. Let upper be len - lower - 1.
    2. Let upperP be ! ToString(𝔽(upper)).
    3. Let lowerP be ! ToString(𝔽(lower)).
    4. Let lowerValue be ! Get(O, lowerP).
    5. Let upperValue be ! Get(O, upperP).
    6. Perform ! Set(O, lowerP, upperValue, true).
    7. Perform ! Set(O, upperP, lowerValue, true).
    8. Set lower to lower + 1.
  7. Return O.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.26 %TypedArray%.prototype.set ( source [ , offset ] )

This method sets multiple values in this TypedArray, reading the values from source. The details differ based upon the type of source. The optional offset value indicates the first element index in this TypedArray where values are written. If omitted, it is assumed to be 0.

It performs the following steps when called:

  1. Let target be the this value.
  2. Perform ? RequireInternalSlot(target, [[TypedArrayName]]).
  3. Assert: target has a [[ViewedArrayBuffer]] internal slot.
  4. Let targetOffset be ? ToIntegerOrInfinity(offset).
  5. If targetOffset < 0, throw a RangeError exception.
  6. If source is an Object that has a [[TypedArrayName]] internal slot, then
    1. Perform ? SetTypedArrayFromTypedArray(target, targetOffset, source).
  7. Else,
    1. Perform ? SetTypedArrayFromArrayLike(target, targetOffset, source).
  8. Return undefined.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.26.1 SetTypedArrayFromTypedArray ( target, targetOffset, source )

The abstract operation SetTypedArrayFromTypedArray takes arguments target (a TypedArray), targetOffset (a non-negative integer or +∞), and source (a TypedArray) and returns either a normal completion containing unused or a throw completion. It sets multiple values in target, starting at index targetOffset, reading the values from source. It performs the following steps when called:

  1. Let targetBuffer be target.[[ViewedArrayBuffer]].
  2. Let targetRecord be MakeTypedArrayWithBufferWitnessRecord(target, seq-cst).
  3. If IsTypedArrayOutOfBounds(targetRecord) is true, throw a TypeError exception.
  4. Let targetLength be TypedArrayLength(targetRecord).
  5. Let srcBuffer be source.[[ViewedArrayBuffer]].
  6. Let srcRecord be MakeTypedArrayWithBufferWitnessRecord(source, seq-cst).
  7. If IsTypedArrayOutOfBounds(srcRecord) is true, throw a TypeError exception.
  8. Let srcLength be TypedArrayLength(srcRecord).
  9. Let targetType be TypedArrayElementType(target).
  10. Let targetElementSize be TypedArrayElementSize(target).
  11. Let targetByteOffset be target.[[ByteOffset]].
  12. Let srcType be TypedArrayElementType(source).
  13. Let srcElementSize be TypedArrayElementSize(source).
  14. Let srcByteOffset be source.[[ByteOffset]].
  15. If targetOffset = +∞, throw a RangeError exception.
  16. If srcLength + targetOffset > targetLength, throw a RangeError exception.
  17. If target.[[ContentType]] is not source.[[ContentType]], throw a TypeError exception.
  18. If IsSharedArrayBuffer(srcBuffer) is true, IsSharedArrayBuffer(targetBuffer) is true, and srcBuffer.[[ArrayBufferData]] is targetBuffer.[[ArrayBufferData]], let sameSharedArrayBuffer be true; otherwise, let sameSharedArrayBuffer be false.
  19. If SameValue(srcBuffer, targetBuffer) is true or sameSharedArrayBuffer is true, then
    1. Let srcByteLength be TypedArrayByteLength(srcRecord).
    2. Set srcBuffer to ? CloneArrayBuffer(srcBuffer, srcByteOffset, srcByteLength).
    3. Let srcByteIndex be 0.
  20. Else,
    1. Let srcByteIndex be srcByteOffset.
  21. Let targetByteIndex be (targetOffset × targetElementSize) + targetByteOffset.
  22. Let limit be targetByteIndex + (targetElementSize × srcLength).
  23. If srcType is targetType, then
    1. NOTE: The transfer must be performed in a manner that preserves the bit-level encoding of the source data.
    2. Repeat, while targetByteIndex < limit,
      1. Let value be GetValueFromBuffer(srcBuffer, srcByteIndex, uint8, true, unordered).
      2. Perform SetValueInBuffer(targetBuffer, targetByteIndex, uint8, value, true, unordered).
      3. Set srcByteIndex to srcByteIndex + 1.
      4. Set targetByteIndex to targetByteIndex + 1.
  24. Else,
    1. Repeat, while targetByteIndex < limit,
      1. Let value be GetValueFromBuffer(srcBuffer, srcByteIndex, srcType, true, unordered).
      2. Perform SetValueInBuffer(targetBuffer, targetByteIndex, targetType, value, true, unordered).
      3. Set srcByteIndex to srcByteIndex + srcElementSize.
      4. Set targetByteIndex to targetByteIndex + targetElementSize.
  25. Return unused.

23.2.3.26.2 SetTypedArrayFromArrayLike ( target, targetOffset, source )

The abstract operation SetTypedArrayFromArrayLike takes arguments target (a TypedArray), targetOffset (a non-negative integer or +∞), and source (an ECMAScript language value, but not a TypedArray) and returns either a normal completion containing unused or a throw completion. It sets multiple values in target, starting at index targetOffset, reading the values from source. It performs the following steps when called:

  1. Let targetRecord be MakeTypedArrayWithBufferWitnessRecord(target, seq-cst).
  2. If IsTypedArrayOutOfBounds(targetRecord) is true, throw a TypeError exception.
  3. Let targetLength be TypedArrayLength(targetRecord).
  4. Let src be ? ToObject(source).
  5. Let srcLength be ? LengthOfArrayLike(src).
  6. If targetOffset = +∞, throw a RangeError exception.
  7. If srcLength + targetOffset > targetLength, throw a RangeError exception.
  8. Let k be 0.
  9. Repeat, while k < srcLength,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let value be ? Get(src, Pk).
    3. Let targetIndex be 𝔽(targetOffset + k).
    4. Perform ? TypedArraySetElement(target, targetIndex, value).
    5. Set k to k + 1.
  10. Return unused.

23.2.3.27 %TypedArray%.prototype.slice ( start, end )

The interpretation and use of the arguments of this method are the same as for Array.prototype.slice as defined in 23.1.3.28.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let srcArrayLength be TypedArrayLength(taRecord).
  4. Let relativeStart be ? ToIntegerOrInfinity(start).
  5. If relativeStart = -∞, let startIndex be 0.
  6. Else if relativeStart < 0, let startIndex be max(srcArrayLength + relativeStart, 0).
  7. Else, let startIndex be min(relativeStart, srcArrayLength).
  8. If end is undefined, let relativeEnd be srcArrayLength; else let relativeEnd be ? ToIntegerOrInfinity(end).
  9. If relativeEnd = -∞, let endIndex be 0.
  10. Else if relativeEnd < 0, let endIndex be max(srcArrayLength + relativeEnd, 0).
  11. Else, let endIndex be min(relativeEnd, srcArrayLength).
  12. Let countBytes be max(endIndex - startIndex, 0).
  13. Let A be ? TypedArraySpeciesCreate(O, « 𝔽(countBytes) »).
  14. If countBytes > 0, then
    1. Set taRecord to MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
    2. If IsTypedArrayOutOfBounds(taRecord) is true, throw a TypeError exception.
    3. Set endIndex to min(endIndex, TypedArrayLength(taRecord)).
    4. Set countBytes to max(endIndex - startIndex, 0).
    5. Let srcType be TypedArrayElementType(O).
    6. Let targetType be TypedArrayElementType(A).
    7. If srcType is targetType, then
      1. NOTE: The transfer must be performed in a manner that preserves the bit-level encoding of the source data.
      2. Let srcBuffer be O.[[ViewedArrayBuffer]].
      3. Let targetBuffer be A.[[ViewedArrayBuffer]].
      4. Let elementSize be TypedArrayElementSize(O).
      5. Let srcByteOffset be O.[[ByteOffset]].
      6. Let srcByteIndex be (startIndex × elementSize) + srcByteOffset.
      7. Let targetByteIndex be A.[[ByteOffset]].
      8. Let endByteIndex be targetByteIndex + (countBytes × elementSize).
      9. Repeat, while targetByteIndex < endByteIndex,
        1. Let value be GetValueFromBuffer(srcBuffer, srcByteIndex, uint8, true, unordered).
        2. Perform SetValueInBuffer(targetBuffer, targetByteIndex, uint8, value, true, unordered).
        3. Set srcByteIndex to srcByteIndex + 1.
        4. Set targetByteIndex to targetByteIndex + 1.
    8. Else,
      1. Let n be 0.
      2. Let k be startIndex.
      3. Repeat, while k < endIndex,
        1. Let Pk be ! ToString(𝔽(k)).
        2. Let kValue be ! Get(O, Pk).
        3. Perform ! Set(A, ! ToString(𝔽(n)), kValue, true).
        4. Set k to k + 1.
        5. Set n to n + 1.
  15. Return A.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.28 %TypedArray%.prototype.some ( callbackfn [ , thisArg ] )

The interpretation and use of the arguments of this method are the same as for Array.prototype.some as defined in 23.1.3.29.

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. If IsCallable(callbackfn) is false, throw a TypeError exception.
  5. Let k be 0.
  6. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ! Get(O, Pk).
    3. Let testResult be ToBoolean(? Call(callbackfn, thisArg, « kValue, 𝔽(k), O »)).
    4. If testResult is true, return true.
    5. Set k to k + 1.
  7. Return false.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.29 %TypedArray%.prototype.sort ( comparefn )

This is a distinct method that, except as described below, implements the same requirements as those of Array.prototype.sort as defined in 23.1.3.30. The implementation of this method may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed properties are not sparse.

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

It performs the following steps when called:

  1. If comparefn is not undefined and IsCallable(comparefn) is false, throw a TypeError exception.
  2. Let obj be the this value.
  3. Let taRecord be ? ValidateTypedArray(obj, seq-cst).
  4. Let len be TypedArrayLength(taRecord).
  5. NOTE: The following closure performs a numeric comparison rather than the string comparison used in 23.1.3.30.
  6. Let SortCompare be a new Abstract Closure with parameters (x, y) that captures comparefn and performs the following steps when called:
    1. Return ? CompareTypedArrayElements(x, y, comparefn).
  7. Let sortedList be ? SortIndexedProperties(obj, len, SortCompare, read-through-holes).
  8. Let j be 0.
  9. Repeat, while j < len,
    1. Perform ! Set(obj, ! ToString(𝔽(j)), sortedList[j], true).
    2. Set j to j + 1.
  10. Return obj.
 Note

Because NaN always compares greater than any other value (see CompareTypedArrayElements), NaN property values always sort to the end of the result when comparefn is not provided.

23.2.3.30 %TypedArray%.prototype.subarray ( start, end )

This method returns a new TypedArray whose element type is the element type of this TypedArray and whose ArrayBuffer is the ArrayBuffer of this TypedArray, referencing the elements in the interval from start (inclusive) to end (exclusive). If either start or end is negative, it refers to an index from the end of the array, as opposed to from the beginning.

It performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? RequireInternalSlot(O, [[TypedArrayName]]).
  3. Assert: O has a [[ViewedArrayBuffer]] internal slot.
  4. Let buffer be O.[[ViewedArrayBuffer]].
  5. Let srcRecord be MakeTypedArrayWithBufferWitnessRecord(O, seq-cst).
  6. If IsTypedArrayOutOfBounds(srcRecord) is true, then
    1. Let srcLength be 0.
  7. Else,
    1. Let srcLength be TypedArrayLength(srcRecord).
  8. Let relativeStart be ? ToIntegerOrInfinity(start).
  9. If relativeStart = -∞, let startIndex be 0.
  10. Else if relativeStart < 0, let startIndex be max(srcLength + relativeStart, 0).
  11. Else, let startIndex be min(relativeStart, srcLength).
  12. Let elementSize be TypedArrayElementSize(O).
  13. Let srcByteOffset be O.[[ByteOffset]].
  14. Let beginByteOffset be srcByteOffset + (startIndex × elementSize).
  15. If O.[[ArrayLength]] is auto and end is undefined, then
    1. Let argumentsList be « buffer, 𝔽(beginByteOffset) ».
  16. Else,
    1. If end is undefined, let relativeEnd be srcLength; else let relativeEnd be ? ToIntegerOrInfinity(end).
    2. If relativeEnd = -∞, let endIndex be 0.
    3. Else if relativeEnd < 0, let endIndex be max(srcLength + relativeEnd, 0).
    4. Else, let endIndex be min(relativeEnd, srcLength).
    5. Let newLength be max(endIndex - startIndex, 0).
    6. Let argumentsList be « buffer, 𝔽(beginByteOffset), 𝔽(newLength) ».
  17. Return ? TypedArraySpeciesCreate(O, argumentsList).

This method is not generic. The this value must be an object with a [[TypedArrayName]] internal slot.

23.2.3.31 %TypedArray%.prototype.toLocaleString ( [ reserved1 [ , reserved2 ] ] )

This is a distinct method that implements the same algorithm as Array.prototype.toLocaleString as defined in 23.1.3.32 except that TypedArrayLength is called in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value has a fixed length when the underlying buffer is not resizable and whose integer-indexed properties are not sparse. However, such optimization must not introduce any observable changes in the specified behaviour of the algorithm.

This method is not generic. ValidateTypedArray is called with the this value and seq-cst as arguments prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

Note

If the ECMAScript implementation includes the ECMA-402 Internationalization API this method is based upon the algorithm for Array.prototype.toLocaleString that is in the ECMA-402 specification.

23.2.3.32 %TypedArray%.prototype.toReversed ( )

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let length be TypedArrayLength(taRecord).
  4. Let A be ? TypedArrayCreateSameType(O, « 𝔽(length) »).
  5. Let k be 0.
  6. Repeat, while k < length,
    1. Let from be ! ToString(𝔽(length - k - 1)).
    2. Let Pk be ! ToString(𝔽(k)).
    3. Let fromValue be ! Get(O, from).
    4. Perform ! Set(A, Pk, fromValue, true).
    5. Set k to k + 1.
  7. Return A.

23.2.3.33 %TypedArray%.prototype.toSorted ( comparefn )

This method performs the following steps when called:

  1. If comparefn is not undefined and IsCallable(comparefn) is false, throw a TypeError exception.
  2. Let O be the this value.
  3. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  4. Let len be TypedArrayLength(taRecord).
  5. Let A be ? TypedArrayCreateSameType(O, « 𝔽(len) »).
  6. NOTE: The following closure performs a numeric comparison rather than the string comparison used in 23.1.3.34.
  7. Let SortCompare be a new Abstract Closure with parameters (x, y) that captures comparefn and performs the following steps when called:
    1. Return ? CompareTypedArrayElements(x, y, comparefn).
  8. Let sortedList be ? SortIndexedProperties(O, len, SortCompare, read-through-holes).
  9. Let j be 0.
  10. Repeat, while j < len,
    1. Perform ! Set(A, ! ToString(𝔽(j)), sortedList[j], true).
    2. Set j to j + 1.
  11. Return A.

23.2.3.34 %TypedArray%.prototype.toString ( )

The initial value of the "toString" property is %Array.prototype.toString%, defined in 23.1.3.36.

23.2.3.35 %TypedArray%.prototype.values ( )

This method performs the following steps when called:

  1. Let O be the this value.
  2. Perform ? ValidateTypedArray(O, seq-cst).
  3. Return CreateArrayIterator(O, value).

23.2.3.36 %TypedArray%.prototype.with ( index, value )

This method performs the following steps when called:

  1. Let O be the this value.
  2. Let taRecord be ? ValidateTypedArray(O, seq-cst).
  3. Let len be TypedArrayLength(taRecord).
  4. Let relativeIndex be ? ToIntegerOrInfinity(index).
  5. If relativeIndex ≥ 0, let actualIndex be relativeIndex.
  6. Else, let actualIndex be len + relativeIndex.
  7. If O.[[ContentType]] is bigint, let numericValue be ? ToBigInt(value).
  8. Else, let numericValue be ? ToNumber(value).
  9. If IsValidIntegerIndex(O, 𝔽(actualIndex)) is false, throw a RangeError exception.
  10. Let A be ? TypedArrayCreateSameType(O, « 𝔽(len) »).
  11. Let k be 0.
  12. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. If k is actualIndex, let fromValue be numericValue.
    3. Else, let fromValue be ! Get(O, Pk).
    4. Perform ! Set(A, Pk, fromValue, true).
    5. Set k to k + 1.
  13. Return A.

23.2.3.37 %TypedArray%.prototype [ @@iterator ] ( )

The initial value of the @@iterator property is %TypedArray.prototype.values%, defined in 23.2.3.35.

23.2.3.38 get %TypedArray%.prototype [ @@toStringTag ]

%TypedArray%.prototype[@@toStringTag] is an accessor property whose set accessor function is undefined. Its get accessor function performs the following steps when called:

  1. Let O be the this value.
  2. If O is not an Object, return undefined.
  3. If O does not have a [[TypedArrayName]] internal slot, return undefined.
  4. Let name be O.[[TypedArrayName]].
  5. Assert: name is a String.
  6. Return name.

This property has the attributes { [[Enumerable]]: false, [[Configurable]]: true }.

The initial value of the "name" property of this function is "get [Symbol.toStringTag]".

23.2.4 Abstract Operations for TypedArray Objects

23.2.4.1 TypedArraySpeciesCreate ( exemplar, argumentList )

The abstract operation TypedArraySpeciesCreate takes arguments exemplar (a TypedArray) and argumentList (a List of ECMAScript language values) and returns either a normal completion containing a TypedArray or a throw completion. 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 @@species, this operation enforces that the constructor function creates an actual TypedArray. It performs the following steps when called:

  1. Let defaultConstructor be the intrinsic object associated with the constructor name exemplar.[[TypedArrayName]] in Table 71.
  2. Let constructor be ? SpeciesConstructor(exemplar, defaultConstructor).
  3. Let result be ? TypedArrayCreateFromConstructor(constructor, argumentList).
  4. Assert: result has [[TypedArrayName]] and [[ContentType]] internal slots.
  5. If result.[[ContentType]] is not exemplar.[[ContentType]], throw a TypeError exception.
  6. Return result.

23.2.4.2 TypedArrayCreateFromConstructor ( constructor, argumentList )

The abstract operation TypedArrayCreateFromConstructor takes arguments constructor (a constructor) and argumentList (a List of ECMAScript language values) and returns either a normal completion containing a TypedArray or a throw completion. It is used to specify the creation of a new TypedArray using a constructor function. It performs the following steps when called:

  1. Let newTypedArray be ? Construct(constructor, argumentList).
  2. Let taRecord be ? ValidateTypedArray(newTypedArray, seq-cst).
  3. If the number of elements in argumentList is 1 and argumentList[0] is a Number, then
    1. If IsTypedArrayOutOfBounds(taRecord) is true, throw a TypeError exception.
    2. Let length be TypedArrayLength(taRecord).
    3. If length < ℝ(argumentList[0]), throw a TypeError exception.
  4. Return newTypedArray.

23.2.4.3 TypedArrayCreateSameType ( exemplar, argumentList )

The abstract operation TypedArrayCreateSameType takes arguments exemplar (a TypedArray) and argumentList (a List of ECMAScript language values) and returns either a normal completion containing a TypedArray or a throw completion. 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. It performs the following steps when called:

  1. Let constructor be the intrinsic object associated with the constructor name exemplar.[[TypedArrayName]] in Table 71.
  2. Let result be ? TypedArrayCreateFromConstructor(constructor, argumentList).
  3. Assert: result has [[TypedArrayName]] and [[ContentType]] internal slots.
  4. Assert: result.[[ContentType]] is exemplar.[[ContentType]].
  5. Return result.

23.2.4.4 ValidateTypedArray ( O, order )

The abstract operation ValidateTypedArray takes arguments O (an ECMAScript language value) and order (seq-cst or unordered) and returns either a normal completion containing a TypedArray With Buffer Witness Record or a throw completion. It performs the following steps when called:

  1. Perform ? RequireInternalSlot(O, [[TypedArrayName]]).
  2. Assert: O has a [[ViewedArrayBuffer]] internal slot.
  3. Let taRecord be MakeTypedArrayWithBufferWitnessRecord(O, order).
  4. If IsTypedArrayOutOfBounds(taRecord) is true, throw a TypeError exception.
  5. Return taRecord.

23.2.4.5 TypedArrayElementSize ( O )

The abstract operation TypedArrayElementSize takes argument O (a TypedArray) and returns a non-negative integer. It performs the following steps when called:

  1. Return the Element Size value specified in Table 71 for O.[[TypedArrayName]].

23.2.4.6 TypedArrayElementType ( O )

The abstract operation TypedArrayElementType takes argument O (a TypedArray) and returns a TypedArray element type. It performs the following steps when called:

  1. Return the Element Type value specified in Table 71 for O.[[TypedArrayName]].

23.2.4.7 CompareTypedArrayElements ( x, y, comparefn )

The abstract operation CompareTypedArrayElements takes arguments x (a Number or a BigInt), y (a Number or a BigInt), and comparefn (a function object or undefined) and returns either a normal completion containing a Number or an abrupt completion. It performs the following steps when called:

  1. Assert: x is a Number and y is a Number, or x is a BigInt and y is a BigInt.
  2. If comparefn is not undefined, then
    1. Let v be ? ToNumber(? Call(comparefn, undefined, « x, y »)).
    2. If v is NaN, return +0𝔽.
    3. Return v.
  3. If x and y are both NaN, return +0𝔽.
  4. If x is NaN, return 1𝔽.
  5. If y is NaN, return -1𝔽.
  6. If x < y, return -1𝔽.
  7. If x > y, return 1𝔽.
  8. If x is -0𝔽 and y is +0𝔽, return -1𝔽.
  9. If x is +0𝔽 and y is -0𝔽, return 1𝔽.
  10. Return +0𝔽.
 Note
This performs a numeric comparison rather than the string comparison used in 23.1.3.30.2.

23.2.5 The TypedArray Constructors

Each TypedArray constructor:

  • is an intrinsic object that has the structure described below, differing only in the name used as the constructor name instead of TypedArray, in Table 71.
  • is a function whose behaviour differs based upon the number and types of its arguments. The actual behaviour of a call of TypedArray depends upon the number and kind of arguments that are passed to it.
  • is not intended to be called as a function and will throw an exception when called in that manner.
  • may be used as the value of an extends clause of a class definition. Subclass constructors that intend to inherit the specified TypedArray behaviour must include a super call to the TypedArray constructor to create and initialize the subclass instance with the internal state necessary to support the %TypedArray%.prototype built-in methods.

23.2.5.1 TypedArray ( ...args )

Each TypedArray constructor performs the following steps when called:

  1. If NewTarget is undefined, throw a TypeError exception.
  2. Let constructorName be the String value of the Constructor Name value specified in Table 71 for this TypedArray constructor.
  3. Let proto be "%TypedArray.prototype%".
  4. Let numberOfArgs be the number of elements in args.
  5. If numberOfArgs = 0, then
    1. Return ? AllocateTypedArray(constructorName, NewTarget, proto, 0).
  6. Else,
    1. Let firstArgument be args[0].
    2. If firstArgument is an Object, then
      1. Let O be ? AllocateTypedArray(constructorName, NewTarget, proto).
      2. If firstArgument has a [[TypedArrayName]] internal slot, then
        1. Perform ? InitializeTypedArrayFromTypedArray(O, firstArgument).
      3. Else if firstArgument has an [[ArrayBufferData]] internal slot, then
        1. If numberOfArgs > 1, let byteOffset be args[1]; else let byteOffset be undefined.
        2. If numberOfArgs > 2, let length be args[2]; else let length be undefined.
        3. Perform ? InitializeTypedArrayFromArrayBuffer(O, firstArgument, byteOffset, length).
      4. Else,
        1. Assert: firstArgument is an Object and firstArgument does not have either a [[TypedArrayName]] or an [[ArrayBufferData]] internal slot.
        2. Let usingIterator be ? GetMethod(firstArgument, @@iterator).
        3. If usingIterator is not undefined, then
          1. Let values be ? IteratorToList(? GetIteratorFromMethod(firstArgument, usingIterator)).
          2. Perform ? InitializeTypedArrayFromList(O, values).
        4. Else,
          1. NOTE: firstArgument is not an Iterable so assume it is already an array-like object.
          2. Perform ? InitializeTypedArrayFromArrayLike(O, firstArgument).
      5. Return O.
    3. Else,
      1. Assert: firstArgument is not an Object.
      2. Let elementLength be ? ToIndex(firstArgument).
      3. Return ? AllocateTypedArray(constructorName, NewTarget, proto, elementLength).

23.2.5.1.1 AllocateTypedArray ( constructorName, newTarget, defaultProto [ , length ] )

The abstract operation AllocateTypedArray takes arguments constructorName (a String which is the name of a TypedArray constructor in Table 71), newTarget (a constructor), and defaultProto (a String) and optional argument length (a non-negative integer) and returns either a normal completion containing a TypedArray or a throw completion. It is used to validate and create an instance of a TypedArray constructor. If the length argument is passed, an ArrayBuffer of that length is also allocated and associated with the new TypedArray instance. AllocateTypedArray provides common semantics that is used by TypedArray. It performs the following steps when called:

  1. Let proto be ? GetPrototypeFromConstructor(newTarget, defaultProto).
  2. Let obj be TypedArrayCreate(proto).
  3. Assert: obj.[[ViewedArrayBuffer]] is undefined.
  4. Set obj.[[TypedArrayName]] to constructorName.
  5. If constructorName is either "BigInt64Array" or "BigUint64Array", set obj.[[ContentType]] to bigint.
  6. Otherwise, set obj.[[ContentType]] to number.
  7. If length is not present, then
    1. Set obj.[[ByteLength]] to 0.
    2. Set obj.[[ByteOffset]] to 0.
    3. Set obj.[[ArrayLength]] to 0.
  8. Else,
    1. Perform ? AllocateTypedArrayBuffer(obj, length).
  9. Return obj.

23.2.5.1.2 InitializeTypedArrayFromTypedArray ( O, srcArray )

The abstract operation InitializeTypedArrayFromTypedArray takes arguments O (a TypedArray) and srcArray (a TypedArray) and returns either a normal completion containing unused or a throw completion. It performs the following steps when called:

  1. Let srcData be srcArray.[[ViewedArrayBuffer]].
  2. Let elementType be TypedArrayElementType(O).
  3. Let elementSize be TypedArrayElementSize(O).
  4. Let srcType be TypedArrayElementType(srcArray).
  5. Let srcElementSize be TypedArrayElementSize(srcArray).
  6. Let srcByteOffset be srcArray.[[ByteOffset]].
  7. Let srcRecord be MakeTypedArrayWithBufferWitnessRecord(srcArray, seq-cst).
  8. If IsTypedArrayOutOfBounds(srcRecord) is true, throw a TypeError exception.
  9. Let elementLength be TypedArrayLength(srcRecord).
  10. Let byteLength be elementSize × elementLength.
  11. If elementType is srcType, then
    1. Let data be ? CloneArrayBuffer(srcData, srcByteOffset, byteLength).
  12. Else,
    1. Let data be ? AllocateArrayBuffer(%ArrayBuffer%, byteLength).
    2. If srcArray.[[ContentType]] is not O.[[ContentType]], throw a TypeError exception.
    3. Let srcByteIndex be srcByteOffset.
    4. Let targetByteIndex be 0.
    5. Let count be elementLength.
    6. Repeat, while count > 0,
      1. Let value be GetValueFromBuffer(srcData, srcByteIndex, srcType, true, unordered).
      2. Perform SetValueInBuffer(data, targetByteIndex, elementType, value, true, unordered).
      3. Set srcByteIndex to srcByteIndex + srcElementSize.
      4. Set targetByteIndex to targetByteIndex + elementSize.
      5. Set count to count - 1.
  13. Set O.[[ViewedArrayBuffer]] to data.
  14. Set O.[[ByteLength]] to byteLength.
  15. Set O.[[ByteOffset]] to 0.
  16. Set O.[[ArrayLength]] to elementLength.
  17. Return unused.

23.2.5.1.3 InitializeTypedArrayFromArrayBuffer ( O, buffer, byteOffset, length )

The abstract operation InitializeTypedArrayFromArrayBuffer takes arguments O (a TypedArray), buffer (an ArrayBuffer or a SharedArrayBuffer), byteOffset (an ECMAScript language value), and length (an ECMAScript language value) and returns either a normal completion containing unused or a throw completion. It performs the following steps when called:

  1. Let elementSize be TypedArrayElementSize(O).
  2. Let offset be ? ToIndex(byteOffset).
  3. If offset modulo elementSize ≠ 0, throw a RangeError exception.
  4. Let bufferIsFixedLength be IsFixedLengthArrayBuffer(buffer).
  5. If length is not undefined, then
    1. Let newLength be ? ToIndex(length).
  6. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
  7. Let bufferByteLength be ArrayBufferByteLength(buffer, seq-cst).
  8. If length is undefined and bufferIsFixedLength is false, then
    1. If offset > bufferByteLength, throw a RangeError exception.
    2. Set O.[[ByteLength]] to auto.
    3. Set O.[[ArrayLength]] to auto.
  9. Else,
    1. If length is undefined, then
      1. If bufferByteLength modulo elementSize ≠ 0, throw a RangeError exception.
      2. Let newByteLength be bufferByteLength - offset.
      3. If newByteLength < 0, throw a RangeError exception.
    2. Else,
      1. Let newByteLength be newLength × elementSize.
      2. If offset + newByteLength > bufferByteLength, throw a RangeError exception.
    3. Set O.[[ByteLength]] to newByteLength.
    4. Set O.[[ArrayLength]] to newByteLength / elementSize.
  10. Set O.[[ViewedArrayBuffer]] to buffer.
  11. Set O.[[ByteOffset]] to offset.
  12. Return unused.

23.2.5.1.4 InitializeTypedArrayFromList ( O, values )

The abstract operation InitializeTypedArrayFromList takes arguments O (a TypedArray) and values (a List of ECMAScript language values) and returns either a normal completion containing unused or a throw completion. It performs the following steps when called:

  1. Let len be the number of elements in values.
  2. Perform ? AllocateTypedArrayBuffer(O, len).
  3. Let k be 0.
  4. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be the first element of values.
    3. Remove the first element from values.
    4. Perform ? Set(O, Pk, kValue, true).
    5. Set k to k + 1.
  5. Assert: values is now an empty List.
  6. Return unused.

23.2.5.1.5 InitializeTypedArrayFromArrayLike ( O, arrayLike )

The abstract operation InitializeTypedArrayFromArrayLike takes arguments O (a TypedArray) and arrayLike (an Object, but not a TypedArray or an ArrayBuffer) and returns either a normal completion containing unused or a throw completion. It performs the following steps when called:

  1. Let len be ? LengthOfArrayLike(arrayLike).
  2. Perform ? AllocateTypedArrayBuffer(O, len).
  3. Let k be 0.
  4. Repeat, while k < len,
    1. Let Pk be ! ToString(𝔽(k)).
    2. Let kValue be ? Get(arrayLike, Pk).
    3. Perform ? Set(O, Pk, kValue, true).
    4. Set k to k + 1.
  5. Return unused.

23.2.5.1.6 AllocateTypedArrayBuffer ( O, length )

The abstract operation AllocateTypedArrayBuffer takes arguments O (a TypedArray) and length (a non-negative integer) and returns either a normal completion containing unused or a throw completion. It allocates and associates an ArrayBuffer with O. It performs the following steps when called:

  1. Assert: O.[[ViewedArrayBuffer]] is undefined.
  2. Let elementSize be TypedArrayElementSize(O).
  3. Let byteLength be elementSize × length.
  4. Let data be ? AllocateArrayBuffer(%ArrayBuffer%, byteLength).
  5. Set O.[[ViewedArrayBuffer]] to data.
  6. Set O.[[ByteLength]] to byteLength.
  7. Set O.[[ByteOffset]] to 0.
  8. Set O.[[ArrayLength]] to length.
  9. Return unused.

23.2.6 Properties of the TypedArray Constructors

Each TypedArray constructor:

  • has a [[Prototype]] internal slot whose value is %TypedArray%.
  • has a "length" property whose value is 3𝔽.
  • has a "name" property whose value is the String value of the constructor name specified for it in Table 71.
  • has the following properties:

23.2.6.1 TypedArray.BYTES_PER_ELEMENT

The value of TypedArray.BYTES_PER_ELEMENT is the Element Size value specified in Table 71 for TypedArray.

This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

23.2.6.2 TypedArray.prototype

The initial value of TypedArray.prototype is the corresponding TypedArray prototype intrinsic object (23.2.7).

This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

23.2.7 Properties of the TypedArray Prototype Objects

Each TypedArray prototype object:

  • has a [[Prototype]] internal slot whose value is %TypedArray.prototype%.
  • is an ordinary object.
  • does not have a [[ViewedArrayBuffer]] or any other of the internal slots that are specific to TypedArray instance objects.

23.2.7.1 TypedArray.prototype.BYTES_PER_ELEMENT

The value of TypedArray.prototype.BYTES_PER_ELEMENT is the Element Size value specified in Table 71 for TypedArray.

This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

23.2.7.2 TypedArray.prototype.constructor

The initial value of the "constructor" property of the prototype for a given TypedArray constructor is the constructor itself.

23.2.8 Properties of TypedArray Instances

TypedArray instances are TypedArrays. Each TypedArray instance inherits properties from the corresponding TypedArray prototype object. Each TypedArray instance has the following internal slots: [[TypedArrayName]], [[ViewedArrayBuffer]], [[ByteLength]], [[ByteOffset]], and [[ArrayLength]].