We're currently designing a site that has some tracking pixels hard coded into the DOM. One of the pixels returns with a 204 response code(as it should), but Chrome and Firefox make the request twice.
If the request is made asynchronously, there is only one request.
Is there are a reason why a browser would retry a request with a 204 no content response, is this a valid behavior?
to repro:
<html>
<body>
<img src="some/source/url.gif" />
</body>
</html>
and then have your webserver respond to the src url with a 204 response code.