runtime: Blazor globalization inconsistency between WASM and Server

Describe the bug

Working on updates to the Blazor Glob/Loc topic on https://github.com/dotnet/AspNetCore.Docs/pull/22525. cc: @hishamco

Either I’ve hit a bug or a personal knowledge gap: Globalization of a number isn’t consistent across Blazor Server and Blazor WebAssembly.

• If a knowledge gap that I have, then I’ll address this behavior in the topic’s updates.
• If a bug, then here it is.

To Reproduce

Blazor WebAssembly (✔️ Working-as-expected Case)

1. Create a new Blazor WebAssembly app from the project template.

2. Add CultureExample1 component to the app’s Pages folder:

   @page "/culture-example-1"
   @using System.Globalization
   @using System.Threading
   
   <h1>Culture Example 1</h1>
   
   <!-- 
       Updated code here, but screenshot is this comment will be left as-is.
       I'll add a screenshot of this output at the end of this issue.
   -->
   <ul>
       <li><b>CultureInfo.CurrentCulture</b>: @CultureInfo.CurrentCulture</li>
       <li><b>CultureInfo.CurrentUICulture</b>: @CultureInfo.CurrentUICulture</li>
       <li><b>Thread.CurrentThread.CurrentCulture</b>: @Thread.CurrentThread.CurrentCulture</li>
       <li><b>Thread.CurrentThread.CurrentUICulture</b>: @Thread.CurrentThread.CurrentUICulture</li>
   </ul>
   
   <h2>Rendered values</h2>
   
   <ul>
       <li><b>Date</b>: @dt</li>
       <li><b>number</b>: @number.ToString("N2")</li>
   </ul>
   
   @code {
       private DateTime dt = DateTime.Now;
       private double number = 1999.69;
   }
   

3. Run the app. Use a browser with Peruvian Spanish (es-PE) as the first language choice:

   

   The date AND number are globalized (i.e., in Spanish: date is day-month format + 24-hour clock & number has a comma decimal and period separator). ✔️ All good. ✔️

Blazor Server (❌ Inconsistent/Not-working-as-expected Case)

1. Create a new Blazor Server app from the project template.

2. Add loc services:

   services.AddLocalization();
   

3. Add loc middleware to the pipeline immediately after Routing Middleware:

   app.UseRequestLocalization(new RequestLocalizationOptions()
       .AddSupportedCultures(new[] { "en-US", "es-PE" })
       .AddSupportedUICultures(new[] { "en-US", "es-PE" }));
   

4. Add the same CultureExample1 component ☝️ to the app’s Pages folder.

5. Run the app. Use a browser with Peruvian Spanish (es-PE) as the first language choice:

The date is globalized ✔️, BUT the number isn’t ❌ (i.e., the number doesn’t have a comma decimal and period separator).

Is this the expected outcome, or is this a 🐞? If expected behavior, why? … because I’ll need to address this delta in the doc.

Exceptions (if any)

None

Further technical details

• ASP.NET Core version

  5.0.6

• Include the output of dotnet --info

  .NET SDK (reflecting any global.json):
   Version:   5.0.300
   Commit:    2e0c8c940e
  
  Runtime Environment:
   OS Name:     Windows
   OS Version:  10.0.19043
   OS Platform: Windows
   RID:         win10-x64
   Base Path:   C:\Program Files\dotnet\sdk\5.0.300\
  
  Host (useful for support):
    Version: 5.0.6
    Commit:  478b2f8c0e
  
  .NET SDKs installed:
    3.1.302 [C:\Program Files\dotnet\sdk]
    5.0.202 [C:\Program Files\dotnet\sdk]
    5.0.300 [C:\Program Files\dotnet\sdk]
  
  .NET runtimes installed:
    Microsoft.AspNetCore.All 2.1.28 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
    Microsoft.AspNetCore.All 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
    Microsoft.AspNetCore.App 2.1.28 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
    Microsoft.AspNetCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
    Microsoft.AspNetCore.App 3.1.15 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
    Microsoft.AspNetCore.App 5.0.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
    Microsoft.AspNetCore.App 5.0.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
    Microsoft.NETCore.App 2.1.28 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
    Microsoft.NETCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
    Microsoft.NETCore.App 3.1.15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
    Microsoft.NETCore.App 5.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
    Microsoft.NETCore.App 5.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
    Microsoft.WindowsDesktop.App 3.1.15 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
    Microsoft.WindowsDesktop.App 5.0.5 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
    Microsoft.WindowsDesktop.App 5.0.6 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  

• The IDE (VS / VS Code/ VS4Mac) you’re running on, and its version

  Visual Studio 16.10.0