Force text content-type

[joehand]

It seems to me that Chrome will block all json sendBeacon's right now.

This may break a lot, there is probably a nicer way to do it. Please let me know =).

[yoshuawuyts]

I was wondering what was going on here, so I chased it down to https://github.com/dxa4481/CORS. Turns out navigator.sendBeacon() now sends an OPTIONS preflight request to the server to figure out if the current client is allowed to write to it.

E.g. probably do something like:

if (req.type === 'OPTIONS') {
  res.setHeader('access-control-allow-origin', '*')
  res.setHeader('access-control-allow-methods', '*')
  res.setHeader('access-control-allow-headers', '*')
  res.setHeader('access-control-allow-credentials', 'true')
}
res.end(200)

And in prod replace the values for the name of your domain, and the values being sent. I think this would be _the right way to do things_™. Going to be adding it to bankai right away!

[joehand]

Did you try this out? The spec says the browser is supposed to send the preflight. But it was my impression that Chrome incorrectly implemented it without preflight checks (and then firefox copied them). From the chrome bug:

Regarding ETA for (A), it turned out to be not a quick work given Chromium's architecture. The CORS code lives in the renderer. There's no reliable way to keep a fetch for sendBeacon alive while waiting for preflight being processed in the browser process. It requires some work.

Search for preflight for a bit more context on that page. Also helpful comment.

It seems a bit broken all around right now unfortunately. That is why I thought using text may be best solution for now (its what google analytics does too).

[yoshuawuyts]

Woah, no I haven't tried it out yet. I thought I understood the bug correctly after reading it, but guess it's time to make a repro to figure out how to handle it. Thanks for pointing out!

[yoshuawuyts]

😢 you're completely right. I misread the error, and looks like this is indeed the only way around it. Ughhhhhhhhhhhhhhhhhhhhhh.

[yoshuawuyts]

v1.0.2 ✨