feat(fast-build): strip state-passing binding attrs from root custom elements#7403
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feat(fast-build): strip state-passing binding attrs from root custom elements#7403
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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>
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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 — e.g.list="{{list}}"becamelist="[Array]"orsomeData="[Object]". These attributes existed solely to forward state through the old attribute-based child state mechanism; with entry-level rendering that mechanism is bypassed, making the attributes both redundant and noisy.This PR strips any attribute whose value is a pure
{{expr}}double-brace binding from root custom element opening tags in the rendered HTML output. Static attributes (id,class,disabled, etc.) are preserved.Additionally,
render_entry_with_templatesis now exposed as a WASM binding and the@microsoft/fast-buildCLI is updated to use it when templates are provided, so the fixture build tool uses entry-level semantics by default.📑 Test Plan
npm run build:fixtures -w @microsoft/fast-htmlregenerates correctly:attribute,binding, andeventfixtures no longer include resolved{{binding}}attrs on root elementscargo test— 182 tests across all suites)✅ Checklist
General
$ npm run change