SignalR typescript client fails to add custom headers

[fallenwood]

Describe the bug

I try to add custom headers when creating a new SignalR connection, but it does not show in devtools.

To Reproduce

Here is the link to the demo https://github.com/fallenwood/signalr-header-report-demo
I have added a X-Test-Token header but it is missing.
Here is the snapshot

Exceptions (if any)

N/A

Further technical details

• ASP.NET Core version: net5.0
• The IDE (VS / VS Code/ VS4Mac) you're running on, and its version: Visual Studio/Command Line
• Include the output of dotnet --info:

dotnet --info Output

> dotnet --info
.NET SDK (reflecting any global.json):
 Version:   5.0.402
 Commit:    e9d3381880

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19043
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\5.0.402\

Host (useful for support):
  Version: 5.0.11
  Commit:  f431858f8b

.NET SDKs installed:
  3.1.414 [C:\Program Files\dotnet\sdk]
  5.0.401 [C:\Program Files\dotnet\sdk]
  5.0.402 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 3.1.19 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 3.1.19 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.19 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
  https://aka.ms/dotnet-download

[BrennanConroy]

You cannot set headers on Websocket requests in the browser. The docs mention this for the headers property
https://docs.microsoft.com/aspnet/core/signalr/configuration?view=aspnetcore-5.0&tabs=javascript#configure-client-options-1

[fallenwood]

Okay, thanks for the answer, then I will use long polling instead of websockets.