Re: [w3c/IndexedDB] Clarify usage of resizable ArrayBuffer as keys (Issue #509)

ArnaudBienner left a comment (w3c/IndexedDB#509)

Consensus from TPAC2026 was (@SteveBeckerMSFT correct me if I'm wrong) that there is no reason to forbid usage of resizable array buffers as keys. And that they shall be turned into a fixed-size array buffer.

**Turns out we probably don't need a spec change after all.**

Re-reading the spec to [convert a value to a key](https://w3c.github.io/IndexedDB/#convert-a-key-to-a-value), we have (for binary step):
> 2. Let buffer be the result of executing the ECMAScript ArrayBuffer constructor with len.

Note we only provide the `len` argument.

So this calls [`ArrayBuffer`'s constructor](https://tc39.es/ecma262/#sec-arraybuffer-length) without `options` argument, which then calls [`AllocateArrayBuffer`](https://tc39.es/ecma262/#sec-allocatearraybuffer) with empty `requestedMaxByteLength` so this returns a regular (fixed size) `ArrayBuffer`.
Because:
> 2. If maxByteLength is present and maxByteLength is not empty, let allocatingResizableBuffer be true; else **let allocatingResizableBuffer be false**.


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Received on Wednesday, 28 October 2026 10:49:11 UTC