Can Razor Class Library pack static files (js, css

Maybe duplicate of this already, but since that post does not have any answer, I am posting this question.

The new Razor Class Library is awesome, but it cannot pack libraries files (like jQuery, shared CSS).

Can I somehow reuse the CSS across multiple Razor Page projects, either using Razor Class Library or anything else (my purpose is that, multiple websites use the same CSS, and a single change applies to all projects).

I have tried creating the folder wwwroot in the Razor Class Library project, but it does not work as expected (and I can understand why).

You need to embed your static assets into your Razor Class Library assembly. I think the best way to get how to do it is to take a look at ASP.NET Identity UI source codes.

You should take the following 4 steps to embed your assets and serve them.

Edit the csproj file of your Razor Class Library and add the following lines.

 <PropertyGroup>
  ....
       <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
  ....
 </PropertyGroup>

 <ItemGroup>
     ....
     <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.1.2" />
     <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.1.1" />
     <PackageReference Include="Microsoft.Extensions.FileProviders.Embedded" Version="2.1.1" />
     <PackageReference Include="Microsoft.NET.Sdk.Razor" Version="$(MicrosoftNETSdkRazorPackageVersion)" PrivateAssets="All" />
    .....
 </ItemGroup>

<ItemGroup>
    <EmbeddedResource Include="wwwroot\**\*" />
    <Content Update="**\*.cshtml" Pack="false" />
</ItemGroup>

In your Razor Class Library, create the following class to serve and route the assets. (it assumes your assets are located at wwwroot folder)

public class UIConfigureOptions : IPostConfigureOptions<StaticFileOptions>
{
    public UIConfigureOptions(IHostingEnvironment environment)
    {
        Environment = environment;
    }
    public IHostingEnvironment Environment { get; }

    public void PostConfigure(string name, StaticFileOptions options)
    {
        name = name ?? throw new ArgumentNullException(nameof(name));
        options = options ?? throw new ArgumentNullException(nameof(options));

        // Basic initialization in case the options weren't initialized by any other component
        options.ContentTypeProvider = options.ContentTypeProvider ?? new FileExtensionContentTypeProvider();
        if (options.FileProvider == null && Environment.WebRootFileProvider == null)
        {
            throw new InvalidOperationException("Missing FileProvider.");
        }

        options.FileProvider = options.FileProvider ?? Environment.WebRootFileProvider;

        var basePath = "wwwroot";

        var filesProvider = new ManifestEmbeddedFileProvider(GetType().Assembly, basePath);
        options.FileProvider = new CompositeFileProvider(options.FileProvider, filesProvider);
    }
}

Make the dependent web application to use your Razor Class Library router. In the ConfigureServices method of Startup Class, add the following line.
```
services.ConfigureOptions(typeof(UIConfigureOptions));
```
So, now you can add a reference to your file. ( let's assume it's located at wwwroot/js/app.bundle.js).
```
<script src="~/js/app.bundle.js" asp-append-version="true"></script>
```