mdn
webassembly.api.Memory.Memory - Document the compatability status of 4GB heap
What type of issue is this?
Missing compatibility data
What information was incorrect, unhelpful, or incomplete?
WebAssembly added support of 4GB heap after https://github.com/WebAssembly/spec/issues/1116, but the compatability status is not documented.
What browsers does this problem apply to, if applicable?
Firefox, Safari, Chromium (Chrome, Edge 79+, Opera, Samsung Internet)
What did you expect to see?
Compatability status of browsers found yet:
- Chrome 83 https://v8.dev/blog/4gb-wasm-memory
- Firefox 89 https://bugzilla.mozilla.org/show_bug.cgi?id=1676441
- Safari 15.2 https://webkit.org/blog/12140/new-webkit-features-in-safari-15-2/
Did you test this? If so, how?
Build a wasm binary that can allocate memory, with MAXIMUM_MEMORY=4GB, and grow pages to 65536
Can you link to any release notes, bugs, pull requests, or MDN pages related to this?
- Chrome 83 https://v8.dev/blog/4gb-wasm-memory
- Firefox 89 https://bugzilla.mozilla.org/show_bug.cgi?id=1676441
- Safari 15.2 https://webkit.org/blog/12140/new-webkit-features-in-safari-15-2/
Do you have anything more you want to share?
No response
MDN URL
https://developer.mozilla.org/en-US/docs/WebAssembly/Reference/JavaScript_interface/Memory/Memory
MDN metadata
MDN page report details
- Query:
webassembly.api.Memory.Memory - Report started: 2025-09-08T07:42:13.733Z
There were a couple of updates, and I'm not sure how we could track these evolutions in BCD:
- Bumped maximum memory limit to 4 GiB in https://github.com/WebAssembly/spec/pull/1121
- Bumped initial memory limit to 4 GiB in https://github.com/WebAssembly/spec/pull/1174
- Introduced 64-bit memory limit of 16 GiB in https://github.com/WebAssembly/spec/commit/525a53cbfc9e8b733b1129731bdb6efa326f51a1
AFAIK the first one (Bumped maximum memory limit to 4 GiB) is most useful for devs, but if the compatability status of the first two diffs from browsers and runtimes, I'd prefer to have both documented. The third one is a different thing which I believe should be part of the memory64 proposal.