feat(builtins): implement JsWeakMap safe wrapper by KaustubhOG · Pull Request #4738 · boa-dev/boa

KaustubhOG · 2026-02-26T10:26:01Z

Implements JsWeakMap as a safe Rust wrapper around the ECMAScript WeakMap builtin, as part of #2098.

Changes

core/engine/src/object/builtins/jsweakmap.rs — new JsWeakMap wrapper with all methods
core/engine/src/object/builtins/mod.rs — registered and re-exported JsWeakMap
examples/src/bin/jsweakmap.rs — usage example

Methods implemented

new — creates an empty WeakMap
get — retrieves value by key
set — inserts a key-value pair
has — checks key existence
delete — removes a key
get_or_insert — upsert with default value
get_or_insert_computed — upsert with callback
from_object — converts JsObject to JsWeakMap

Follows the same pattern as JsMap and JsSet.

Closes part of #2098

github-actions · 2026-02-26T10:35:26Z

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,862	52,862	0
Passed	49,504	49,504	0
Ignored	2,262	2,262	0
Failed	1,096	1,096	0
Panics	0	0	0
Conformance	93.65%	93.65%	0.00%

jedel1043

Looks great! Thanks!

codecov · 2026-02-27T23:02:02Z

Codecov Report

❌ Patch coverage is 0% with 39 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.23%. Comparing base (6ddc2b4) to head (57289e9).
⚠️ Report is 699 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/object/builtins/jsweakmap.rs	0.00%	39 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4738      +/-   ##
==========================================
+ Coverage   47.24%   57.23%   +9.99%     
==========================================
  Files         476      551      +75     
  Lines       46892    60466   +13574     
==========================================
+ Hits        22154    34610   +12456     
- Misses      24738    25856    +1118

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KaustubhOG · 2026-02-27T23:06:07Z

Hi @jedel1043! Thank you for the quick reviews and guidance on #4738 really appreciated the clear feedback.

Implements `JsWeakSet` as a safe Rust wrapper around the ECMAScript `WeakSet` builtin, as part of #2098. ## Changes - `core/engine/src/object/builtins/jsweakset.rs` — new `JsWeakSet` wrapper with all methods - `core/engine/src/object/builtins/mod.rs` — registered and re-exported `JsWeakSet` - `examples/src/bin/jsweakset.rs` — usage example ## Methods implemented - `new` — creates an empty WeakSet - `add` — adds an object to the set - `has` — checks if an object exists - `delete` — removes an object - `from_object` — converts `JsObject` to `JsWeakSet` Follows the same pattern as `JsWeakMap` (#4738) and `JsSet`. Closes part of #2098

Implements `JsWeakMap` as a safe Rust wrapper around the ECMAScript `WeakMap` builtin, as part of boa-dev#2098. ## Changes - `core/engine/src/object/builtins/jsweakmap.rs` — new `JsWeakMap` wrapper with all methods - `core/engine/src/object/builtins/mod.rs` — registered and re-exported `JsWeakMap` - `examples/src/bin/jsweakmap.rs` — usage example ## Methods implemented - `new` — creates an empty WeakMap - `get` — retrieves value by key - `set` — inserts a key-value pair - `has` — checks key existence - `delete` — removes a key - `get_or_insert` — upsert with default value - `get_or_insert_computed` — upsert with callback - `from_object` — converts `JsObject` to `JsWeakMap` Follows the same pattern as `JsMap` and `JsSet`. Closes part of boa-dev#2098

Implements `JsWeakSet` as a safe Rust wrapper around the ECMAScript `WeakSet` builtin, as part of boa-dev#2098. ## Changes - `core/engine/src/object/builtins/jsweakset.rs` — new `JsWeakSet` wrapper with all methods - `core/engine/src/object/builtins/mod.rs` — registered and re-exported `JsWeakSet` - `examples/src/bin/jsweakset.rs` — usage example ## Methods implemented - `new` — creates an empty WeakSet - `add` — adds an object to the set - `has` — checks if an object exists - `delete` — removes an object - `from_object` — converts `JsObject` to `JsWeakSet` Follows the same pattern as `JsWeakMap` (boa-dev#4738) and `JsSet`. Closes part of boa-dev#2098

Implements `JsWeakMap` as a safe Rust wrapper around the ECMAScript `WeakMap` builtin, as part of boa-dev#2098. ## Changes - `core/engine/src/object/builtins/jsweakmap.rs` — new `JsWeakMap` wrapper with all methods - `core/engine/src/object/builtins/mod.rs` — registered and re-exported `JsWeakMap` - `examples/src/bin/jsweakmap.rs` — usage example ## Methods implemented - `new` — creates an empty WeakMap - `get` — retrieves value by key - `set` — inserts a key-value pair - `has` — checks key existence - `delete` — removes a key - `get_or_insert` — upsert with default value - `get_or_insert_computed` — upsert with callback - `from_object` — converts `JsObject` to `JsWeakMap` Follows the same pattern as `JsMap` and `JsSet`. Closes part of boa-dev#2098

Implements `JsWeakSet` as a safe Rust wrapper around the ECMAScript `WeakSet` builtin, as part of boa-dev#2098. ## Changes - `core/engine/src/object/builtins/jsweakset.rs` — new `JsWeakSet` wrapper with all methods - `core/engine/src/object/builtins/mod.rs` — registered and re-exported `JsWeakSet` - `examples/src/bin/jsweakset.rs` — usage example ## Methods implemented - `new` — creates an empty WeakSet - `add` — adds an object to the set - `has` — checks if an object exists - `delete` — removes an object - `from_object` — converts `JsObject` to `JsWeakSet` Follows the same pattern as `JsWeakMap` (boa-dev#4738) and `JsSet`. Closes part of boa-dev#2098

feat(builtins): implement JsWeakMap safe wrapper

14ac3fa

KaustubhOG requested a review from a team as a code owner February 26, 2026 10:26

This was referenced Feb 26, 2026

Tracking issue for JsObject safe wrappers #2098

Open

feat(builtins): implement JsWeakSet safe wrapper #4739

Merged

jedel1043 reviewed Feb 26, 2026

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Comment thread core/engine/src/object/builtins/jsweakmap.rs Outdated

docs(builtins): replace Same as comments with MDN links in JsWeakMap

d2024f3

jedel1043 requested changes Feb 27, 2026

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Comment thread core/engine/src/object/builtins/jsweakmap.rs Outdated

jedel1043 added C-Builtins PRs and Issues related to builtins/intrinsics A-API Changes related to public APIs Waiting On Author Waiting on PR changes from the author A-Enhancement New feature or request labels Feb 27, 2026

refactor(builtins): import NativeWeakMap from weak_map module

57289e9

jedel1043 approved these changes Feb 27, 2026

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jedel1043 enabled auto-merge February 27, 2026 22:44

jedel1043 removed the Waiting On Author Waiting on PR changes from the author label Feb 27, 2026

jedel1043 added this pull request to the merge queue Feb 27, 2026

Merged via the queue into boa-dev:main with commit 0d58601 Feb 27, 2026
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feat(builtins): implement JsWeakMap safe wrapper#4738

feat(builtins): implement JsWeakMap safe wrapper#4738
jedel1043 merged 3 commits intoboa-dev:mainfrom
KaustubhOG:feat/js-weak-map-wrapper

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KaustubhOG commented Feb 26, 2026

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Test262 conformance changes

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