Blazor HTML attribute prefix

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

the NU HTML Checker (https://validator.w3.org) mark syntax errors on html attributes rendered by blazor framework with prefix “bl”

e.g.

Error: Attr i _bl_7209af49-b4f6-4891-96ba-d21c353e56de not allowed on element i at this point.

<i class="rzi d-inline-flex justify-content-center align-items-center" id="3Ki1DEtSSk" _bl_7209af49-b4f6-4891-96ba-d21c353e56de="">
Attributes for element i:
[Global attributes](https://html.spec.whatwg.org/multipage/#global-attributes)

Expected Behavior

Code/ HTML generated by blazor does not raise errors on NU HTML Checker (https://validator.w3.org) validation because of invalid HTML attributes.

The issue / syntax seems correct if the prefix “data-” will be used. e.g. “data-bl …”, “data-bl_”

it seems the prefix will be added in https://github.com/dotnet/aspnetcore/blob/b6630137b2109042dc11ece3164782e451647bff/src/Components/Web.JS/src/Rendering/ElementReferenceCapture.ts#L15

possibly using data- as additional prefix will solve the issue.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

6.0.200

Anything else?

Host (useful for support): Version: 6.0.2 Commit: 839cdfb0ec

.NET SDKs installed: 3.1.101 [C:\Program Files\dotnet\sdk] 6.0.200 [C:\Program Files\dotnet\sdk]

.NET runtimes installed: Microsoft.AspNetCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.AspNetCore.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App] Microsoft.NETCore.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 5.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.NETCore.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App] Microsoft.WindowsDesktop.App 3.1.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App] Microsoft.WindowsDesktop.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[SteveSandersonMS]

Thanks for the extra info. It’s definitely something we can keep an eye on, in case it becomes a more common issue.

[SteveSandersonMS]

The _bl_* attributes are added by client-side JS code for interactively-rendered elements that have a @ref. The attributes are not present in the initial HTML.

As such, if you only use SSR, you will not see these attributes at all (since SSR-only elements are not interactively-rendered).