Stage 4 tracking

[michaelficarra]

ECMA-262 PR: tc39/ecma262#3802

test262.fyi links:

• zip: https://test262.fyi/#built-ins/Iterator/zip
• zipKeyed: https://test262.fyi/#built-ins/Iterator/zipKeyed

implementations:

• SpiderMonkey
  • tracking: https://bugzilla.mozilla.org/show_bug.cgi?id=1911379
  • 2025-07-11: implementation: https://hg-edge.mozilla.org/mozilla-central/rev/9cbb3d709884
  • 2026-02-24: shipped in Firefox 148: https://bugzilla.mozilla.org/show_bug.cgi?id=2003333
• JavaScriptCore
  • tracking: https://bugs.webkit.org/show_bug.cgi?id=303246
  • implementation (unreviewed and unmerged for 5 months at time of writing): [JSC] Implement Iterator.zip and Iterator.zipKeyed WebKit/WebKit#54565
• V8
  • tracking: https://issues.chromium.org/issues/465357675
  • 2026-03-09: implemented Iterator.zip (not zipKeyed): https://chromium-review.googlesource.com/c/v8/v8/+/7605659
• LibJS
  • 2026-02-26: implemented: LibJS: Implement Iterator.zip and Iterator.zipKeyed LadybirdBrowser/ladybird#8191
• QuickJS NG
  • 2026-01-07: implemented Iterator.zip: Add Iterator.zip quickjs-ng/quickjs#1274
  • 2026-01-07: implemented Iterator.zipKeyed: Add Iterator.zipKeyed quickjs-ng/quickjs#1277
  • 2026-02-10: shipped in v0.12.0
• Kiesel
  • 2026-01-25: implemented: https://codeberg.org/kiesel-js/kiesel/commit/630e1be8e31ca531732d885ee239f0f9675fc046

[ljharb]

These are polyfilled (with es-abstract in close to spec language) in https://npmjs.com/es-iterator-helpers

[styfle]

Did this reach stage 4?

[ljharb]

it reached stage 3 this past week.

[styfle]

There must be a typo in this tc39 post https://bsky.app/profile/tc39.es/post/3mmhlitpxrq2a

[bakkot]

It did get stage 4. I suspect @ljharb is thinking of the very similarly named proposal-iterator-join, which got stage 3.

[michaelficarra]

For future reference @styfle, as a delegate, you can just read the notes to see what happened at a meeting.