Implement ES2024 Resizable ArrayBuffer

[anivar]

Implements ES2024 Resizable ArrayBuffer and ES2025 auto-length TypedArray views.

ES2024 Resizable ArrayBuffer

Constructor accepts maxByteLength option:

new ArrayBuffer(8, { maxByteLength: 16 })

Resizable buffers can grow/shrink in-place:

buffer.resize(12)  // grows to 12 bytes
buffer.resize(4)   // shrinks to 4 bytes

New properties:

• resizable - true if buffer has maxByteLength
• maxByteLength - maximum allowed size

ES2025 Auto-length TypedArrays

TypedArrays on resizable buffers without explicit length track buffer size dynamically:

const rab = new ArrayBuffer(16, { maxByteLength: 32 });
const ta = new Uint8Array(rab);  // auto-length view
console.log(ta.length);  // 16

rab.resize(24);
console.log(ta.length);  // 24

Fixed-length views throw TypeError when buffer resizes out of bounds:

const fixedView = new Uint8Array(rab, 0, 4);
rab.resize(2);
fixedView.at(0);  // TypeError: TypedArray is out of bounds

Implementation

NativeArrayBuffer:

• Uses int primitive for maxByteLength (-1 for fixed-length)
• Lambda pattern for new methods
• Data preserved during resize via System.arraycopy, new bytes zeroed

NativeTypedArrayView:

• isAutoLength flag for auto-length views
• updateLength() recalculates length for auto-length views
• isTypedArrayOutOfBounds() validates bounds on resized buffers
• All methods call validateAndGetLength() before access

Errors:

• TypeError if not resizable, detached, or out of bounds
• RangeError if resize exceeds maxByteLength

Test262 Results

59 tests now passing (227→169 TypedArray failures)

All return-abrupt-from-this-out-of-bounds tests now pass across TypedArray methods: at, copyWithin, entries, every, fill, filter, find, findIndex, findLast, findLastIndex, forEach, includes, indexOf, join, keys, lastIndexOf, map, reduce, reduceRight, reverse, set, slice, some, sort, toLocaleString, values.

Fixed-length property tests (byteLength, byteOffset, length) on resizable buffers also passing.

[gbrail]

Thanks for working on this and for your patience as we ask lots of questions...