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…elements
When rendering entry HTML via render_entry_with_templates / render_entry_template_with_locator, root custom elements receive the full root state directly. Any attribute whose value is a pure {{expr}} double-brace binding was only needed to forward state via the attribute-based child state mechanism — with entry-level rendering that mechanism is bypassed, so these attributes are now stripped from the rendered HTML output.
Examples stripped: list="{{list}}", item_parent="{{item_parent}}", someData="{{someData}}"
Static attributes (id, class, disabled, etc.) are preserved.
Changes:
- attribute.rs: add is_state_passing_binding() and strip_entry_attrs() (strips client-only attrs + {{binding}} attrs)
- directive.rs: build_element_open_tag gains is_entry param; uses strip_entry_attrs when true
- wasm.rs: expose render_entry_with_templates WASM binding
- fast.js CLI: use render_entry_with_templates when templates are provided
- tests/custom_elements.rs: 4 new tests for entry-level attr stripping behaviour
- Regenerate attribute, binding, event fixture index.html files
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…s-on-root-elements
…ents; strip non-primitives
For entry-level root custom elements, {{binding}} attribute values are now resolved
from root state:
- Primitive (string/number/bool): rendered with resolved value, e.g. text="{{msg}}" → text="Hello world"
- Non-primitive (array/object/null): stripped — cannot be an HTML attribute value
Static attributes (no binding syntax) are passed through unchanged.
This is implemented via build_entry_element_open_tag in directive.rs which replaces
the earlier strip_entry_attrs approach. HTML escaping is applied to string values.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
…s-on-root-elements
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Pull request overview
This PR updates @microsoft/fast-build entry-level rendering so that root custom elements no longer emit noisy “state-passing” {{binding}} attributes in the rendered HTML, and exposes the entry-level renderer via WASM for the CLI to use when templates are provided.
Changes:
- Add entry-level opening-tag handling for root custom elements (resolve primitive
{{...}}attrs, strip non-primitives). - Expose
render_entry_with_templatesas a WASM binding and switch thefast-buildCLI to use it when templates are present. - Add integration tests and documentation updates describing the entry-level attribute behavior.
Reviewed changes
Copilot reviewed 7 out of 8 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| packages/fast-build/bin/fast.js | Switch CLI rendering path to entry-level semantics when templates are provided. |
| crates/microsoft-fast-build/src/wasm.rs | Export render_entry_with_templates for WASM consumers. |
| crates/microsoft-fast-build/src/directive.rs | Implement entry-level root custom element opening-tag attribute handling. |
| crates/microsoft-fast-build/tests/custom_elements.rs | Add integration tests for entry-level root custom element attribute behavior. |
| crates/microsoft-fast-build/README.md | Document entry-level root element attribute handling semantics. |
| crates/microsoft-fast-build/DESIGN.md | Update design notes to reflect new entry-level opening-tag behavior. |
| change/@microsoft-fast-html-f43a3bf8-58f2-4224-a8b1-d248b5f47b7e.json | Record fixture regen for @microsoft/fast-html. |
| change/@microsoft-fast-build-strip-entry-binding-attrs.json | Record minor feature change for @microsoft/fast-build. |
- Use strip_client_only_attrs as first step in build_entry_element_open_tag
to avoid duplicating the client-only attr filter list
- Handle ?attr="{{expr}}" boolean attribute bindings: evaluate as boolean,
emit bare attr name (without ?) when truthy, omit when falsy
- Fix wasm.rs doc comment for render_entry_with_templates to accurately
describe primitive-kept / non-primitive-stripped behavior
- Add tests: test_root_custom_element_boolean_attr_binding_truthy and _falsy
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Apr 8, 2026
Regenerate repeat/index.html after rebasing onto main (which includes PR #7403 entry-attribute stripping and PR #7380 when fixture). Changes reflect correct entry-element behavior: - Non-primitive binding attrs (list, someData) stripped from opening tag - test-element-no-item-repeat-binding now renders empty repeat since list="{{emptyList}}" overrides root list with [] in merged state Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
janechu
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Apr 8, 2026
Regenerate repeat-event/index.html after rebasing onto main (which includes #7381 repeat fixture, #7380 when fixture, and #7403 entry-attribute stripping). Non-primitive binding attrs (items) are now stripped from entry element opening tags; primitive attrs (show-names="true") are preserved. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull Request
📖 Description
When rendering the top-level entry HTML via
render_entry_with_templates/render_entry_template_with_locator, root custom elements receive the full root state directly. Before this change, any{{binding}}attribute on a root element was resolved and written into the rendered HTML as-is — e.g.list="{{items}}"becamelist="[Array]". These noisy rendered values are now handled correctly:string,number,boolean) — resolved and rendered. e.g.text="{{message}}"→text="Hello world".array,object,null) — stripped. State is available directly in the template via entry-level rendering.?attr="{{expr}}"boolean bindings — evaluated as a boolean; bare attribute name emitted when truthy, omitted when falsy.id="main",disabled, etc.) — passed through unchanged.Additionally,
render_entry_with_templatesis now exposed as a WASM binding and the CLI updated to use it. The implementation usesstrip_client_only_attrsas a first pass to avoid duplicating the client-only attr filter list.📑 Test Plan
?attrtruthy/falsynpm run build:fixturesregenerates correctly —attribute,binding,eventfixtures match expected output✅ Checklist
General
$ npm run change