SSE - Can I intercept an EventSource source/stream ?

[gerazenobi]

Hi there 👋

I would like to know whether it is possible, and if so how, to intercept and fake SSE message streams.

The client code is using standard EventSource, e.g.:

                // ...
                eventSource = new EventSource("http://myUrl:8000/mySSEEventsEndpoint");
                eventSource.onmessage = function(event) {
                    // ... process messages
                };

What I would want is being able to bypass the backend (intercept) and inject a series of stubbed SSE messages.

I am not interested in the temporality of the messages: they could arrive/be returned "all at once" to the source.

Thanks in advance for any information.