Can I add properties to a websocket object?

console.dir (socket.id)
console.dir (socket)

Object.assign (this.control.id, socket.id)

console.dir (socket.id)
console.dir (socket)

Object.assign (this.control.id, socket.id)

console.dir (socket.id)
console.dir (socket)

Object.assign (this.control.id, socket.id)

console.dir (socket.id)
console.dir (socket)

Object.assign (this.control.id, socket.id)

I am adding an id object to the sockets to help keep track of them, but something is giving rise to this behaviour, which doesn't seem to make sense