Hi, you don’t specify in your post above, but I surmise that since you started in JS you may be using Web Sockets to connect to your broker. Is this the case?
We do not currently support Guaranteed/Assured messaging over Web Sockets (in our C/C#/Java RTO apis). It is a feature which is coming but won’t be available until summer 2020 (estimated).
SessionProperties.Host Property is a list of supported protocols.