Collocation JavaScript file breaks Hot Reload

[RyouBakura]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

The mere presence of a collocated Javascript file, e.g. "Home.razor.js" breaks Hot Reload functionality for .css files. However C# Hot Reload is not affected.

Expected Behavior

CSS Hot Reload should work.

Steps To Reproduce

1. Clone the repo project. It's a fresh Blazor Web App.

Click to expand. It was created with the following settings:

3. Run the project and change the color property in "Home.razor.css" to see that Hot Reload is working!
4. Stop debugging.
5. Add a new file called "Home.razor.js"
6. Run the project again and change the color property in "Home.razor.css" once more.
7. You should now see this dialog telling you it went wrong:

Exceptions (if any)

18:19 18.29 HotReloadDestroyer: Scoped CSS file changed: Z:\Dotnet\HotReloadDestroyer\Components\Pages\Home.razor.css
18:19 18.35 HotReloadDestroyer: Building scoped CSS files in project HotReloadDestroyer
18:19 18.59 HotReloadDestroyer: [Error] Building scoped CSS files failed for project HotReloadDestroyer
18:19 18.59 Invalid changes were found. Please refer to the Error List window to fix those issues.
18:19 27.95 HotReloadDestroyer (Web server): Hot reload session complete

.NET Version

9.0.100-preview.7.24407.12

Anything else?

I've encountered this problem in both .NET 8 and .NET 9.

[MackinnonBuck]

Looks like the failing target is ApplyJsModules:

The JS module file '<PROJECT_DIR>\Components\Pages\Home.razor.js' was defined but no associated razor component or view was found for it

...which gets logged from here. Need to do a bit more digging as to why it's failing.

[javiercn]

@MackinnonBuck I'm pretty sure the cause of this is because there's a target that's not running for JS.

We did a specific thing for CSS hot reload, and not a general thing, so I imagine that when the file gets added, only a subset of the targets needed run and that breaks things.

[dgoldm]

@RyouBakura thanks for pinpointing the issue. Having to restart my app after every change in css was driving me crazy. At least now I can temporarily delete the js file while working on my layouts.
I hope this gets fixed ASAP

[MrChriZ]

Is this fix in .NET 9 rc2? As I'm still seeing it.

[dgoldm]

I'm seconding @MrChriZ 's comment.
This is still broken. And very annoying.

[XorZy]

The issue is still present in 9.0.100.
Please reopen this issue, this is a major inconvenience which makes it nearly impossible to work.