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Published 20 hours ago • verified publisher icon w3c

Chrome, Safari and Firefox behave differently when beacon blocked by CSP

Open chernodub opened this issue 9 months ago • 1 comments

Hi, I found out that some browser engines behave differently when a beacon request is blocked by CSP policy (it happens when domain is not specified in connect-src section of the CSP header). As far as I see, the spec does not define what is the "right" value to return in this case: https://www.w3.org/TR/beacon/#return-value

Actual behavior

  • Safari, Chrome: sendBeacon returns true
  • Firefox: sendBeacon returns false

Expected behavior

Work consistently across browsers.

ps: I'm not 100% sure if this is the right place to open an issue, but I figured that it would be reasonable to first figure out what behavior is “canonical” in this scenario. I would greatly appreciate any thoughts on this. Thanks!

The reproduction is here: https://chernodub.dev/beacon (source code https://github.com/chernodub/chernodub.github.io/blob/main/src/pages/beacon.html)

Steps to reproduce

Try playing with reproduction in different browsers

chernodub avatar May 08 '24 08:05 chernodub