Sample
Verify custom element lifecycle callbacks, automatic DOM node upgrade upon definition, and Shadow DOM event propagation in happy-dom
sha256:423dae2528fdc439252e398872c6b51cf55d774b2ad6d555a83a33dc647ab701
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
- Verify custom element lifecycle callbacks, automatic DOM node upgrade upon definition, and Shadow DOM event propagation in happy-dom HOW
- Packages
-
happy-dom 20.11.2
- Environment
- node
- Created
- 2026-08-17T13:15:47Z
Contract
- customElements.define registers custom element lifecycle callbacks (connectedCallback, disconnectedCallback, attributeChangedCallback) that execute synchronously upon DOM tree mutation and observed attribute modification.
- Defining a custom element automatically upgrades matching pre-existing elements in the active DOM tree, replacing the node and triggering connectedCallback.
- attachShadow creates open or closed shadow roots where mode open exposes element.shadowRoot and mode closed keeps element.shadowRoot as null.
- Composed events dispatched inside a shadow root bubble across the shadow boundary through light DOM ancestors to Window, populating composedPath with the shadow root, host, and document nodes.
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