Blazor JS Interop page gives example of Dispose pattern which causes unhandled exceptions.

[willdean]

Description

The Blazor JS Interop page contains the following example of disposing a JS Module:

  async ValueTask IAsyncDisposable.DisposeAsync()
    {
        if (module is not null)
        {
            await module.DisposeAsync();
        }
    }

However, this can lead to an unhandled exception being thrown (noticeable in the debugger, even if it's silent elsewhere).

This has been reported before: In this issue dotnet/aspnetcore#38822 Steve Sanderson said:

This is as designed. The exception here is JSDisconnectedException, indicating that the JS interop call cannot be issued because there's no active connection. In this case you probably want to ignore such exceptions, so you should use a try/catch for that specific exception type in this place.

To me, this implies that the code example on the doc page should look more like this:

    async ValueTask IAsyncDisposable.DisposeAsync()
    {
        if (module is not null)
        {
            try
            {
                await module.DisposeAsync();
            }
            catch (JSDisconnectedException)
            {
            }
        }
    }

I'd imagine that it's not the intention that example code should throw unhandled exceptions.

Page URL

https://learn.microsoft.com/en-us/aspnet/core/blazor/javascript-interoperability/?view=aspnetcore-9.0&preserve-view=true

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/blazor/javascript-interoperability/index.md

Document ID

49fa31d8-72a6-01a1-027d-6edeac9e0fc4

Article author

@guardrex

Related Issues

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[guardrex]

Thanks @willdean ... We'll take a look at this for further work in the article in a week or two. We're still trying to recover from the .NET 9 release and have a lot of balls in the air right now. I'll schedule this for a look ASAP 🏃‍♂.