Sample
core-js 3.40.0: Demonstrate that core-js polyfilled Object.groupBy returns a null-prototype object rather than a standard Object instance.
Verified sample for npm core-js 3.40.0: Demonstrate that core-js polyfilled Object.groupBy returns a null-prototype object rather than a standard Object…
sha256:94ecf6a51292da84f82ff7f1f2b8cb3ab6b763507c9dd919398f8a0f581b31dd
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
node linux x64 node node npm
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| node 22 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1 |
2026-08-16 |
| node 22 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1 |
2026-08-18 |
Case
HOW- Goal
- Demonstrate that core-js polyfilled Object.groupBy returns a null-prototype object rather than a standard Object instance.
- Packages
- Symbols
-
- Object.groupBy
- Environment
- node
- Created
- 2026-08-16T18:09:03Z
Contract
- Object.groupBy returns an object with a null prototype rather than Object.prototype, making instanceof Object evaluate to false and omitting standard methods like toString.
- Object.getPrototypeOf(Object.groupBy([1], x => 'key')) is null
- Object.groupBy([1], x => 'key') instanceof Object is false
- Object.groupBy([1], x => 'key').toString throws a TypeError
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs