HTTP responses for status codes that should have no body

[bsmth]

Summary

HTTP responses with 204, 304, (1XX) should not contain content (a body). For historical / legacy reasons, browsers have tolerated junk data in <=HTTP/1.1 that precedes the status line because servers occasionally included content in responses that should not have a body. HTTP spec versions after 1.1 are strict / explicit in forbidding content in these cases.

I'm removing compat info from prose in MDN docs, and putting this into compat data instead, as this seems the most appropriate place for this to live on.

204 (No Content) is the most obvious place, but I'm open to alternatives somewhere (outside of http/status.json?)

Related issues

• fix(http): Clarify content length in 204 responses content#37928
• https://bugzilla.mozilla.org/show_bug.cgi?id=1356614

[caugner]

I'm not sure we should document this in BCD, as the spec doesn't seem to specify any browser behavior, even if the HTTP 204 response contains content.

Couldn't we keep a more concise warning about browsers potentially rejecting the data in content instead?

[bsmth]

Couldn't we keep a more concise warning about browsers potentially rejecting the data in content instead?

I'm not opposed to this, it's tricky to find a place where this information should live and where it's truly useful for MDN readers. There's some options:

• https://developer.mozilla.org/en-US/docs/Web/HTTP/Messages
• https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
• https://developer.mozilla.org/en-US/docs/Glossary/HTTP_Content

In general, the linked PR in content is making it more explicit in responses where there should be no content, which is the standard way if all is well. The information we're trying to capture or re-home is "how much junk data browsers tolerate in responses that shouldn't have a body", which seems to be interesting mostly to people implementing clients with legacy interop more than anything else.

@hamishwillee what do you think about this? Any objections to putting this in content with a list of response statuses that shouldn't include a body?