Sample
Demonstrate that @babel/preset-env forceAllTransforms bypasses modern targets while respecting modules: false, and that preserving arrow functions under full transforms requires excluding transform-parameters alongside transform-arrow-functions.
sha256:a1e19eae1148972757a6923ccc11bdc0ba903db8cdc27be7819fddd2e4962401
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- node
- Operating system
- linux
- Architecture
- x64
- Runtime
- node
- Language
- node
- Package manager
- npm
Verification-run environments
- Execution context
- node 22
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- node 22
- Language
- javascript
- Package manager
- npm
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17
Case
- Goal
- Demonstrate that @babel/preset-env forceAllTransforms bypasses modern targets while respecting modules: false, and that preserving arrow functions under full transforms requires excluding transform-parameters alongside transform-arrow-functions. HOW
- Packages
-
@babel/preset-env 8.0.2
@babel/core 8.0.1
- Environment
- node
- Created
- 2026-08-17T06:37:33Z
Commonly assumed
Excluding transform-arrow-functions is sufficient to preserve arrow functions under forceAllTransforms, and forceAllTransforms transpiles ES module syntax into CommonJS.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- When forceAllTransforms is enabled, @babel/preset-env downlevels ES2015+ syntax to ES5 regardless of modern targets, but respects modules: false for ES imports/exports and converts arrow functions with default parameters into standard functions unless transform-parameters is also excluded.
- assert modern targets without forceAllTransforms retain native arrow functions, template literals, class fields, and optional chaining
- assert forceAllTransforms downlevels ES2015+ syntax to ES5 while leaving ES module import/export declarations untouched when modules: false
- assert excluding transform-arrow-functions alone still converts arrow functions with default parameters into regular functions via transform-parameters
- assert excluding both transform-arrow-functions and transform-parameters preserves arrow functions with default parameters
- assert exclude supports RegExp patterns to match full plugin names
- assert passing an invalid plugin string name to exclude causes @babel/preset-env to throw a validation error
- assert modules: 'commonjs' under forceAllTransforms transpiles both syntax and ES module declarations to CommonJS
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- node 22 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9