MSW & EventSource on Firefox

[kgibb]

Does anyone use msw for mocking text/event-stream responses and test against Firefox?

The following works in Chrome but Firefox refuses the EventSource connection.

const encoder = new TextEncoder();

const handler = http.get("/api/sse", () => {
    const stream = new ReadableStream({
        start(controller) {
            setInterval(() => {
                controller.enqueue(encoder.encode(`event:message\ndata:{"id": "${getUUID()}" }\n\n`));
            }, 1000);
        }
    });

    return new HttpResponse(stream, {
        headers: {
            "Content-Type": "text/event-stream"
        }
    });
});

I don't think it's a problem with mockServiceWorker.js as I can fetch and read the stream in the browser console. The response signature is very similar to an actual server which Firefox does allow.

The error in the EventSource onerror callback is empty.

Has anyone any insights?

[kettanaito]

Hi, @kgibb. Thanks for raising this.

Can you try #2299? It's work-in-progress but it should work everywhere. If you can verify the issue persists with that API as well that'd be great.

[DRMPN]

Hi @kgibb!

I also use MSW for mocking SSE and I've attached a screenshot of errors in #2117. Are these the same errors you're encountering?
I've tested it against both Firefox and Brave browsers.