How to use JavaScript to provide a client certificate to a SIgnalR hub

I managed (through numerous sites and stackoverflow questions) to create my own SignalR host that will process and validate SSL client certificates. I can access this hub from .Net code using HubConnection.AddClientCertificate (). I can see the certificate on the server etc.

However, I need to call the same server / hub from Jscript with a client certificate, and I haven't found anything to indicate that this action can be performed.