Allow JS root components to reinitialize on circuit restart #64536
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Pull request overview
This PR enables JS root components to reinitialize when a Blazor circuit restarts, while still preventing multi-host scenarios. Previously, any attempt to re-enable JS root components would throw an error, even for valid circuit restart scenarios.
Key Changes:
- Modified JS root component initialization logic to differentiate between circuit restarts (same renderer type) and multi-host scenarios (different renderer types)
- Consolidated test coverage by moving dynamic JS root component tests into the main state persistence test suite
- Removed configuration-based component registration in favor of always registering the test component
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
src/Components/Web.JS/src/Rendering/JSRootComponents.ts |
Added currentRendererId and hasInitializedJsComponents tracking to support circuit restart while preventing multi-host scenarios |
src/Components/Web.JS/src/Rendering/WebRendererInteropMethods.ts |
Updated enableJSRootComponents call to include rendererId parameter |
src/Components/test/E2ETest/Tests/StatePersistenceTest.cs |
Added test for persistent state support in dynamic JS roots |
src/Components/test/E2ETest/Tests/StatePersistanceJSRootTest.cs |
Removed separate test file (consolidated into StatePersistenceTest.cs) |
src/Components/test/testassets/Components.TestServer/RazorComponentEndpointsStartup.cs |
Simplified to always register dynamic JS root component instead of using configuration |
src/Components/test/testassets/Components.TestServer/Program.cs |
Removed separate test scenario for JS root components |
javiercn
reviewed
Nov 26, 2025
Comment on lines
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to
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| if (!hasInitializedJsComponents) { | ||
| // Call the registered initializers. This is an arbitrary subset of the JS component types that are registered | ||
| // on the .NET side - just those of them that require some JS-side initialization (e.g., to register them | ||
| // as custom elements). | ||
| for (const [initializerIdentifier, componentIdentifiers] of Object.entries(jsComponentInitializers)) { | ||
| const initializerFunc = DotNet.findJSFunction(initializerIdentifier, 0) as JSComponentInitializerCallback; | ||
| for (const componentIdentifier of componentIdentifiers) { | ||
| const parameters = jsComponentParameters[componentIdentifier]; | ||
| initializerFunc(componentIdentifier, parameters); | ||
| } | ||
| } | ||
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| hasInitializedJsComponents = true; |
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I think there is potentially more to this than just fixing this error. Try and trigger a pause and a resume operation manually. There are likely other things that fail? (happy to be wrong through)
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Update: the disconnection test should be done on JS root component.
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Fixes #64523.
Tests cleanup:
This PR reverts changes to tests architecture done in #64159 to avoid fixing multiple issues in one PR. It removes the additional test file and moves
PersistentStateIsSupportedInDynamicJSRootstoPersistentState-connected test file.Framework fixes:
The goal of the changes is to differentiate between the following scenarios:
Multi-Host / Different Renderer Types (Unsupported - Throws Error)
rendererId= 0)enableJSRootComponents: With Server'srendererIdandmanagerInstancemanageris set,currentRendererId = 0enableJSRootComponents: With WebAssembly'srendererId(e.g., 1) and its ownmanagerInstance.Same Renderer Type Circuit Restart (Supported)
managervariable holds the oldDotNetObjectReferencefrom Circuit 1.currentRendererIdholds the renderer ID (e.g., Server renderer = 0)enableJSRootComponents: The framework calls this with:rendererId](e.g., 0 for Server)managerInstance(a fresh DotNetObjectReference from Circuit 2)managerInstancereplaces the old stale onehasInitializedJsComponentsis already true, so initializers don't run again.Blazor.rootComponents.add()with the new valid manager.