Should cross-origin beacons with an ArrayBuffer payload do a CORS preflight?

[cdumez]

If I understand the processing model [1] correctly:

• data is not null do corsMode will be set to "cors".
• As per [2], my understanding is that mimeType should be null, therefore, step 6 at [1] wouldn't reset corsMode.

As a result, my understanding would be that a CORS-preflight should be done. Based on my local testing, I don't think Blink does such preflight.

[1] https://w3c.github.io/beacon/#sec-processing-model [2] https://fetch.spec.whatwg.org/#concept-bodyinit-extract

[igrigorik]

(updated)

As a result, my understanding would be that a CORS-preflight should be done. Based on my local testing, I don't think Blink does such preflight.

Yes, that's a bug, see crbug.com/720283; will be fixed once we land crbug.com/695939.

I believe processing algorithm is correct.

On a related note, and as a heads up, ptal @ https://github.com/w3c/web-platform-tests/pull/6655.

[igrigorik]

@cdumez I don't believe there is anything spec actionable here. Can we resolve this one?

[cdumez]

Sure. You answered my question, thank you.