[Blazor] Initializers fixes for Blazor Web by javiercn · Pull Request #50860 · dotnet/aspnetcore

javiercn · 2023-09-21T15:47:36Z

Updates the initializers in Blazor to include platform specific variants that can be tailored to each runtime.

Description

Initializers in Blazor WebAssembly and Server allowed library authors and applications to define JS modules that would be automatically imported by the JS Blazor runtime when it booted up.
These JS modules were used to tweak the configuration of a given Blazor Runtime or perform additional initialization of JS libraries on the page.
Since Blazor Web can have multiple runtimes running simultaneously on the page at the same time (server and webassembly), libraries can run into issues like initializing the wrong runtime, running initialization multiple times, or having to wait until we initialize a runtime to apply custom styles and other logic that might be necessary for the correct function of their libraries.
This PR addresses that by defining runtime specific extension points that libraries can use to tweak a concrete runtime when it boots as well as an initial extension point to target Blazor Web specific scenarios that don't involve a runtime.

Fixes #50187

Customer Impact

Existing libraries with initializers won't be initialized until an interactive component is rendered on the page.
Initialization logic might run more than once for existing libraries, causing all sorts of unpredictable side effects.
- For example, double initialization.

Regression?

Yes
No

It's not a regression in the sense that Blazor Web is a new scenario, but a feature that library authors depend on (for example the Fluent UI Blazor components library does) will not work reliably in this scenario.

Risk

High
Medium
Low

The fix is an extension to the existing mechanism to give library authors a path forward. The previous mechanism is disabled by default in Blazor Web scenarios and this fix gives library authors a path forward to make the feature work reliably here. In addition to that, with this fix app developers are not blocked on library authors updating their packages to work on Blazor web, as they can author adapters for the initializers within their apps that use the extension defined by the fix.

Verification

Manual (required)
Automated

Packaging changes reviewed?

Yes
No
N/A

When servicing release/2.1

Make necessary changes in eng/PatchConfig.props

javiercn · 2023-09-22T15:28:07Z

+        if (beforeWebAssemblyStart) {
+          options.webAssembly.initializers.beforeStart.push(beforeWebAssemblyStart);
+        }
+
+        if (afterWebAssemblyStarted) {
+          options.webAssembly.initializers.afterStarted.push(afterWebAssemblyStarted);
+        }
+
+        if (beforeServerStart) {
+          options.circuit.initializers.beforeStart.push(beforeServerStart);
+        }
+
+        if (afterServerStarted) {
+          options.circuit.initializers.afterStarted.push(afterServerStarted);
+        }
+
+        if (afterWebStarted) {
+          jsInitializer.afterStartedCallbacks.push(afterWebStarted);
+        }
+
+        if (beforeWebStart) {
+          return beforeWebStart(options);
+        }


We essentially collect all the callbacks from the initializer for server and webassembly, and set them in their respective options types. After that, we start running the beforeWebStart callback and trigger the afterWebStarted callbacks once we are done with the first render.

wtgodbe · 2023-09-27T18:32:41Z

@javiercn if this is still needed it should be retargeted to release/8.0

javiercn · 2023-09-28T10:05:57Z

@wtgodbe I will retarget it once I am done with it.

MackinnonBuck

I still need to go through things in more detail, but the approach looks good to me so far.

ghost · 2023-10-02T23:07:51Z

Hi @javiercn. Please make sure you've updated the PR description to use the Shiproom Template. Also, make sure this PR is not marked as a draft and is ready-to-merge.

To learn more about how to prepare a servicing PR click here.

danmoseley · 2023-10-03T17:29:23Z

this has the servicing-consider label but I don't see a mail for it yet.

ghost · 2023-10-04T14:56:42Z

Hi @javiercn. This PR was just approved to be included in the upcoming servicing release. Somebody from the @dotnet/aspnet-build team will get it merged when the branches are open. Until then, please make sure all the CI checks pass and the PR is reviewed.

* Updates initializers support to look for runtime specific callbacks * beforeWebStart, afterWebStarted. * beforeWebAssemblyStart, afterWebAssemblyStarted * beforeServerStarts, afterServerStarted * There is a new option on Blazor Server to get a callback when a circuit is opened and closed in Blazor web scenarios. * Blazor web applications ignore old initializers by default and warn in the console of their presence. * Classic initializers can be turned on via a setting in Blazor.start options. * Blazor WebAssembly and Blazor Server applications are updated to prefer the new runtime specific initializers over the classic ones, but will still run the classic ones by default.

Updates the initializers in Blazor to include platform specific variants that can be tailored to each runtime. ## Description * Initializers in Blazor WebAssembly and Server allowed library authors and applications to define JS modules that would be automatically imported by the JS Blazor runtime when it booted up. * These JS modules were used to tweak the configuration of a given Blazor Runtime or perform additional initialization of JS libraries on the page. * Since Blazor Web can have multiple runtimes running simultaneously on the page at the same time (server and webassembly), libraries can run into issues like initializing the wrong runtime, running initialization multiple times, or having to wait until we initialize a runtime to apply custom styles and other logic that might be necessary for the correct function of their libraries. * This PR addresses that by defining runtime specific extension points that libraries can use to tweak a concrete runtime when it boots as well as an initial extension point to target Blazor Web specific scenarios that don't involve a runtime. Fixes #50187 ## Customer Impact * Existing libraries with initializers won't be initialized until an interactive component is rendered on the page. * Initialization logic might run more than once for existing libraries, causing all sorts of unpredictable side effects. * For example, double initialization. ## Regression? - [ ] Yes - [X] No It's not a regression in the sense that Blazor Web is a new scenario, but a feature that library authors depend on (for example the Fluent UI Blazor components library does) will not work reliably in this scenario. ## Risk - [ ] High - [ ] Medium - [X] Low The fix is an extension to the existing mechanism to give library authors a path forward. The previous mechanism is disabled by default in Blazor Web scenarios and this fix gives library authors a path forward to make the feature work reliably here. In addition to that, with this fix app developers are not blocked on library authors updating their packages to work on Blazor web, as they can author adapters for the initializers within their apps that use the extension defined by the fix. ## Verification - [ ] Manual (required) - [X] Automated ## Packaging changes reviewed? - [ ] Yes - [ ] No - [X] N/A ---- ## When servicing release/2.1 - [ ] Make necessary changes in eng/PatchConfig.props

ghost added area-blazor Includes: Blazor, Razor Components labels Sep 21, 2023

SteveSandersonMS reviewed Sep 21, 2023

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Comment thread src/Components/Web.JS/src/JSInitializers/JSInitializers.Server.ts

javiercn force-pushed the javiercn/blazor-web-initializers branch from d9c6241 to 3c8a14c Compare September 22, 2023 15:10

javiercn marked this pull request as ready for review September 22, 2023 15:20

javiercn requested a review from a team as a code owner September 22, 2023 15:20

javiercn commented Sep 22, 2023

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javiercn force-pushed the javiercn/blazor-web-initializers branch from f5af2d0 to c7e1166 Compare September 22, 2023 20:42

javiercn changed the base branch from release/8.0-rc2 to release/8.0 October 2, 2023 16:03

javiercn force-pushed the javiercn/blazor-web-initializers branch 3 times, most recently from 149d4a9 to c8bb94d Compare October 2, 2023 18:44

MackinnonBuck reviewed Oct 2, 2023

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Comment thread src/Components/Web.JS/src/Boot.Server.Common.ts

Comment thread src/Components/Web.JS/src/Boot.Server.ts

Comment thread src/Components/Web.JS/src/Boot.Server.Common.ts

javiercn added the Servicing-consider Shiproom approval is required for the issue label Oct 2, 2023

MackinnonBuck approved these changes Oct 3, 2023

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javiercn force-pushed the javiercn/blazor-web-initializers branch 2 times, most recently from 9305ae7 to 7f26317 Compare October 4, 2023 11:08

javiercn requested a review from a team as a code owner October 4, 2023 11:08

javiercn force-pushed the javiercn/blazor-web-initializers branch from 7f26317 to 3fb8fff Compare October 4, 2023 13:07

mkArtakMSFT added Servicing-approved Shiproom has approved the issue and removed Servicing-consider Shiproom approval is required for the issue labels Oct 4, 2023

javiercn force-pushed the javiercn/blazor-web-initializers branch from 3fb8fff to 7ca18db Compare October 4, 2023 18:22

mkArtakMSFT merged commit 51f80c7 into release/8.0 Oct 5, 2023

mkArtakMSFT deleted the javiercn/blazor-web-initializers branch October 5, 2023 15:14

ghost added this to the 8.0.0 milestone Oct 5, 2023

guardrex mentioned this pull request Oct 6, 2023

Blazor .NET 8 tracking issue dotnet/AspNetCore.Docs#28161

Closed

guardrex mentioned this pull request Nov 2, 2023

JS initializers 8.0 dotnet/AspNetCore.Docs#30918

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halter73 mentioned this pull request Apr 5, 2024

[Blazor/Web.JS] Add Circuit Handler Notification on Circuit Disconnect #54973

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javiercn mentioned this pull request Sep 6, 2025

Blazor CircuitHandler (Client-Side JS) not Triggering onCircuitClosed in Case of Server-Side Exceptions #54807

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[Blazor] Initializers fixes for Blazor Web#50860

[Blazor] Initializers fixes for Blazor Web#50860
mkArtakMSFT merged 1 commit intorelease/8.0from
javiercn/blazor-web-initializers

javiercn commented Sep 21, 2023 •

edited by mkArtakMSFT

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javiercn commented Sep 21, 2023 •

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