Sample
Configuring treeshake.moduleSideEffects to false silently removes bare side-effect imports lacking consumed bindings, whereas setting it to 'no-external' preserves internal side-effect modules while pruning external ones.
sha256:92601fd5622eb4523c4c39713473c67395bc60dbed071830173bede138b89a13
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
- Configuring treeshake.moduleSideEffects to false silently removes bare side-effect imports lacking consumed bindings, whereas setting it to 'no-external' preserves internal side-effect modules while pruning external ones. HOW
- Packages
-
rollup 4.34.8
- Environment
- node
- Created
- 2026-08-17T11:12:35Z
Commonly assumed
A bare import with no specifiers, such as import './polyfill.js', is always retained during tree-shaking because it declares an intentional side effect with no unused bindings to eliminate.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- Setting treeshake: { moduleSideEffects: false } causes Rollup to strip bare side-effect imports that have no consumed exports, whereas treeshake: { moduleSideEffects: 'no-external' } retains internal side-effect imports and strips unused external ones.
- Executing a bundle built with moduleSideEffects: false leaves global state uninitialized by the stripped polyfill, while executing a bundle built with moduleSideEffects: 'no-external' triggers the top-level side effects on module load.
- Default tree-shaking (moduleSideEffects: true) retains both internal and external side-effect imports unconditionally.
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