How to deregister a function from SignalR client?

Question

Consider the following code:

var connection = new signalR.HubConnectionBuilder().withUrl("/hub").build();

connection.on("ReceiveMessage", (message) => {
    console.log("Once");
});

connection.on("ReceiveMessage", (message) => {
    console.log("Twice");
});

Now when the server sends ReceiveMessage to the client, the browser's console contains... both Once and Twice. Apparently, both functions are invoked.

Problem is, in of my inexperience & lack of knowledge I assumed that registering a new function for the same command (ReceiveMessage in this case) will automatically repleace the previously registered function, if there was any. And I was writing my program with that assumption. I only had to verify this assumption once I started noticing bizzarre behavior of my program.

Can I somehow deregister previously registered handlers? Or should I rewrite my JS code with the assumption that I should only register one function per connection per command?

Answer 1

Yes, all handlers can be unregistered with just the method name.

var connection = new signalR.HubConnectionBuilder().withUrl("/hub").build();

connection.off("ReceiveMessage");
connection.on("ReceiveMessage", (message) => {
    console.log("Once");
});

connection.off("ReceiveMessage");
connection.on("ReceiveMessage", (message) => {
    console.log("Twice");
});