SignalR Core call function when connection is established - signalr.client

Question

When my client successfully connects to the hub, I want the client to immediately join a group. I have a method in my hub to do that, I just need an event handler for when the connection is established, just like
connection.start().done(
function () {
connection.invoke('JoinGroup', 'GroupName');
});
in SignalR for plain ASP.Net.
Can I do that or do I have to set a timer to do it after x seconds after the start(); call was made?
Edit:
I found out I can do
connection.start(
function (){
connection.invoke('JoinGroup', 'GroupName');
}
);
but it tells me that it Cannot send data if the connection is not in the 'Connected' State.
what do?

Answer 1

SignalR is notoriously difficult due to version mismatches etc.
Please see the following article: https://learn.microsoft.com/en-us/aspnet/core/tutorials/signalr?view=aspnetcore-2.1&tabs=visual-studio
In it, there's a section that specifies how to start (and wait for connection to be established):
var connection = new signalR.HubConnectionBuilder().withUrl("/chatHub").build();
connection.start().then(() => {
//try some stuff here :)
})
.catch(function (err) {
//failed to connect
return console.error(err.toString());
});
The javascript client uses promises that have to be resolved/rejected before you can use it.
The other option is to wrap inside async method and await the call (not sure if this will work correctly). Such as:
await connection.start();
//connection should be started now. beware of exceptions though