Intent to ship: JavaScript Symbols as WeakMap keys
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Jon Coppeard
Sep 11, 2025, 4:50:00 AM (13 days ago) Sep 11
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As of Firefox 146 (releasing December 9) I intend to turn Symbols as WeakMap keys on by default on all platforms. It has been developed behind the javascript.options.experimental.symbols_as_weakmap_keys preference. This has shipped in Chrome since version 109 and Safari since version 16.4.
Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1966745
Standard: https://tc39.es/ecma262/multipage/executable-code-and-execution-contexts.html#sec-canbeheldweakly
This feature was previously discussed in this "Intent to prototype" thread: https://groups.google.com/a/mozilla.org/g/dev-platform/c/NNpke-yy9uQ/m/eN5T-9LEAQAJ
Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1966745
Standard: https://tc39.es/ecma262/multipage/executable-code-and-execution-contexts.html#sec-canbeheldweakly
This feature was previously discussed in this "Intent to prototype" thread: https://groups.google.com/a/mozilla.org/g/dev-platform/c/NNpke-yy9uQ/m/eN5T-9LEAQAJ
Jon
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