Adding analyzer to warn about JSInterop calls not wrapped in a try catch block by MayaKirova · Pull Request #67900 · dotnet/aspnetcore

MayaKirova · 2026-07-20T09:33:46Z

Adding analyzer to warn about JSInterop calls not wrapped in a try catch block

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Description

Added analyzer that shows warnning and code fixer that wraps the JSInterop calls (InvokeAsync, InvokeVoidAsync etc.) in try/catch block.

Also added some tests:

Area	Test Scenario	Expected Result
Analyzer	Unguarded `IJSRuntime` extension call (`InvokeVoidAsync`)	Warning is reported
Analyzer	Unguarded `IJSObjectReference` extension call (`InvokeVoidAsync`)	Warning is reported
Analyzer	Unguarded `IJSRuntime.InvokeAsync<T>` call	Warning is reported
Analyzer	Unguarded `IJSObjectReference.InvokeAsync<T>` call	Warning is reported
Analyzer	Unguarded `IJSInProcessRuntime.Invoke<T>` call	Warning is reported
Analyzer	Unguarded `IJSInProcessObjectReference.Invoke<T>` call	Warning is reported
Analyzer	JS interop call already inside `try/catch`	No diagnostic is reported
Analyzer	JS interop call nested in guarded flow (`if` inside `try/catch`)	No diagnostic is reported
Code Fixer	Unguarded awaited `InvokeVoidAsync`	Call is wrapped in `try/catch`
Code Fixer	Unguarded awaited `InvokeAsync<T>`	Call is wrapped in `try/catch`
Code Fixer	Unguarded non-awaited `InvokeVoidAsync`	Call is wrapped in `try/catch`

Fixes #67306

…ch block.

… to string type names. Add more tests accordingly.

… block with at least one catch as guarded. Adding tests accordingly.

…ncompatible code.

…c, InvokeConstructorAsync).

…dd some tests for calls inside lambda expressions.

…erent types of exceptions thrown.

…JSDisconnectedException or generic Exception.

Co-authored-by: Youssef Fahmy <youssefvictor00@gmail.com>

…eption, JSDisconnectedException or generic Exception." This reverts commit 48fa81a.

… be different types of exceptions thrown." This reverts commit 218e570.

Co-authored-by: Ilona Tomkowicz <32700855+ilonatommy@users.noreply.github.com>

….com/MayaKirova/aspnetcore into mkirova/unguarded-JSInterop-analyzer

Co-authored-by: Ilona Tomkowicz <32700855+ilonatommy@users.noreply.github.com>

….com/MayaKirova/aspnetcore into mkirova/unguarded-JSInterop-analyzer

dotnet-policy-service · 2026-07-20T09:34:12Z

Thanks for your PR, @MayaKirova. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

Copilot

Pull request overview

This PR adds a new Components analyzer (and code fix) to warn when JavaScript interop calls aren’t wrapped in a try/catch, aiming to improve resiliency in scenarios like prerendering and disconnected clients.

Changes:

Added JSInteropAnalyzer to report a warning for unguarded JS interop invocations.
Added JSInteropCodeFixProvider plus new unit tests covering diagnostics and fix behavior.
Updated template sample and diagnostics documentation to reflect the new guidance.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/ProjectTemplates/Web.ProjectTemplates/content/RazorClassLibrary-CSharp/ExampleJsInterop.cs	Updates template sample to wrap JS interop calls in `try/catch` and provide clearer failures.
src/Components/Analyzers/test/JSInteropCodeFixProviderTest.cs	Adds tests validating the new code fix behavior.
src/Components/Analyzers/test/JSInteropAnalyzerTest.cs	Adds tests validating diagnostics for various JS interop call shapes and contexts.
src/Components/Analyzers/src/Resources.resx	Adds localized strings for the new diagnostic and code fix.
src/Components/Analyzers/src/JSInteropCodeFixProvider.cs	Introduces a code fix to wrap eligible JS interop calls in `try/catch`.
src/Components/Analyzers/src/JSInteropAnalyzer.cs	Introduces the analyzer logic for detecting unguarded JS interop calls.
src/Components/Analyzers/src/DiagnosticDescriptors.cs	Registers the new diagnostic descriptor and assigns an ID.
docs/list-of-diagnostics.md	Updates the published diagnostic list/range for BL diagnostics.

+                SyntaxFactory.CatchClause()
+                    .WithCatchKeyword(SyntaxFactory.Token(indentList, SyntaxKind.CatchKeyword, SyntaxFactory.TriviaList(SyntaxFactory.Space)))
+                    .WithDeclaration(
+                        SyntaxFactory.CatchDeclaration(
+                            SyntaxFactory.ParseTypeName("Exception"))
+                            .WithCloseParenToken(SyntaxFactory.Token(SyntaxTriviaList.Empty, SyntaxKind.CloseParenToken, eolList)))
+                    .WithBlock(
+                        SyntaxFactory.Block()
+                            .WithOpenBraceToken(SyntaxFactory.Token(indentList, SyntaxKind.OpenBraceToken, eolList))
+                            .WithCloseBraceToken(SyntaxFactory.Token(indentList, SyntaxKind.CloseBraceToken, SyntaxTriviaList.Empty)))),


ilonatommy · 2026-07-20T12:22:30Z

@MayaKirova, we have to wait for #67898, then we can merge/rerun.

ilonatommy · 2026-07-20T15:24:42Z

aspnetcore/src/ProjectTemplates/Web.ProjectTemplates/content/BlazorWebWorker-CSharp/WebWorkerClient.cs

Line 12 in fc4e6e0

await using var module = await jsRuntime.InvokeAsync<IJSObjectReference>(

build

Youssef1313 · 2026-07-21T09:17:19Z

+        catch (JSException ex)
+        {
+            throw new InvalidOperationException("Unable to invoke the web worker JavaScript function.", ex);
+        }


@ilonatommy I'm not sure how is this better than letting the call throw, if an exception is going to propagate up anyways?

It's better because it prevents the warnings that are treated as errors in the template tests and would fail the CI. The alternative would be to supress this warning but that's not a good practice for the template code. User can decide to swallow the exception if they want but I don't think we should promote such a solution in the template.

MayaKirova and others added 30 commits June 30, 2026 14:09

Adding JSInteropAnalyzer to warn about calls not wrapped in a try cat…

9fadd21

…ch block.

Add code fixer that wraps call in try/catch.

0674d53

Minor tweaks and adding tests.

0798c3a

Add more complex checks for JSInterop invocations so we don't compare…

e87321e

… to string type names. Add more tests accordingly.

Tighten the try/catch detection so it only treats calls inside a try…

d9561bc

… block with at least one catch as guarded. Adding tests accordingly.

Apply changes requested in some of the review comments.

1325dce

Limit code fixer to ExpressionStatementSyntax so it doesn't produce u…

6cf6a53

…ncompatible code.

Add tests for additional interop methods (GetValueAsync, SetValueAsyn…

ff91d9e

…c, InvokeConstructorAsync).

Apply review comments - refactoring, remove string comparisons etc. A…

3ed74ab

…dd some tests for calls inside lambda expressions.

Remove unused param.

537d321

Update analyzer to look for a try/catch-all since there could be diff…

218e570

…erent types of exceptions thrown.

Check for exceptions of type InvalidOperationException, JSException, …

48fa81a

…JSDisconnectedException or generic Exception.

Attempt to fix tests by normalising line endings.

702f43d

Fix code fixer try/catch whitespace formatting.

e751f0f

Apply code suggestion.

14f89ca

Co-authored-by: Youssef Fahmy <youssefvictor00@gmail.com>

Revert "Check for exceptions of type InvalidOperationException, JSExc…

fe24238

…eption, JSDisconnectedException or generic Exception." This reverts commit 48fa81a.

Revert "Update analyzer to look for a try/catch-all since there could…

8650a8e

… be different types of exceptions thrown." This reverts commit 218e570.

Apply indentation fix.

2041d8c

Co-authored-by: Ilona Tomkowicz <32700855+ilonatommy@users.noreply.github.com>

Fix typo.

744efdc

Merge branch 'mkirova/unguarded-JSInterop-analyzer' of https://github…

0639f79

….com/MayaKirova/aspnetcore into mkirova/unguarded-JSInterop-analyzer

Remove normalizing of line end in tests.

195f698

Fix resource string formatting.

ee3f01b

Apply rename suggestion.

1238b47

Co-authored-by: Ilona Tomkowicz <32700855+ilonatommy@users.noreply.github.com>

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

a7bb2af

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

28e965d

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

d12a208

Reuse existing trivia when building try/catch statement.

6805d61

Extract and use indent settings from doc.

3d290ab

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

204c83c

Wrap calls in try/catch for example.

879040b

Merge branch 'mkirova/unguarded-JSInterop-analyzer' of https://github…

010e20a

….com/MayaKirova/aspnetcore into mkirova/unguarded-JSInterop-analyzer

Copilot AI review requested due to automatic review settings July 20, 2026 09:33

MayaKirova requested a review from a team as a code owner July 20, 2026 09:33

dotnet-policy-service Bot added the community-contribution Indicates that the PR has been added by a community member label Jul 20, 2026

Copilot started reviewing on behalf of MayaKirova July 20, 2026 09:34 View session

dotnet-policy-service Bot temporarily deployed to copilot-pat-pool July 20, 2026 09:34 Inactive

Copilot AI reviewed Jul 20, 2026

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MayaKirova added 3 commits July 20, 2026 14:04

Adjust descriptor Ids an update diagnostics list.

1082b07

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

ee1c72d

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

83f31b9

ilonatommy approved these changes Jul 20, 2026

View reviewed changes

Merge branch 'main' into mkirova/unguarded-JSInterop-analyzer

879fbfb

ilonatommy enabled auto-merge (squash) July 20, 2026 13:53

build-analysis Bot mentioned this pull request Jul 20, 2026

Known Test Repository Issue Sometimes Misses Test Failures dotnet/dnceng#6411

Open

3 tasks

Add error handling for JS interop in WebWorkerClient methods.

45e8462

auto-merge was automatically disabled July 21, 2026 06:58
Head branch was pushed to by a user without write access

ilonatommy approved these changes Jul 21, 2026

View reviewed changes

ilonatommy merged commit 6b3ab41 into dotnet:main Jul 21, 2026
27 checks passed

ilonatommy added this to the 11.0-preview7 milestone Jul 21, 2026

Youssef1313 reviewed Jul 21, 2026

View reviewed changes

This was referenced Jul 21, 2026

[main] Source code updates from dotnet/aspnetcore dotnet/dotnet#7876

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[release/11.0.1xx-preview7] Source code updates from dotnet/aspnetcore dotnet/dotnet#7909

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dotnet-milestone-bot Bot modified the milestones: 11.0-preview7, 11.0-rc1 Jul 23, 2026

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Adding analyzer to warn about JSInterop calls not wrapped in a try catch block - #67900

Adding analyzer to warn about JSInterop calls not wrapped in a try catch block#67900
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MayaKirova commented Jul 20, 2026

Adding analyzer to warn about JSInterop calls not wrapped in a try catch block

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ilonatommy commented Jul 20, 2026

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