docs: document Deno.serve legacy request abort behavior#3386
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Adds a dedicated page explaining the legacy `request.signal` abort behavior in `Deno.serve`, why it is changing, and how to detect request completion via `info.completed` when opting in to `--unstable-no-legacy-abort`. The page is reachable from the unstable flags reference and via the `docs.deno.com/go/unstable-no-legacy-abort` short link, which the Deno runtime deprecation warning points to. It intentionally stays out of the sidebar navigation.
bartlomieju
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…35713) The `Deno.serve` legacy request abort deprecation warning added in #34397 pointed users at https://docs.deno.com/runtime/reference/migrate-deprecations/, a page that does not exist. This repoints it at the stable `docs.deno.com/go/unstable-no-legacy-abort` short link. That short link resolves to a new dedicated docs page (denoland/docs#3386) that explains why the `request.signal` abort behavior is changing, what `--unstable-no-legacy-abort` does, and how to detect when a request has been fully delivered. The warning now also names `info.completed` directly, since knowing when a response has been fully sent is the most common reason people relied on the legacy abort. That promise (on the handler's `ServeHandlerInfo` argument) resolves once the response, including a streaming body, has been delivered and rejects if delivery fails partway, which is the mode-independent replacement for watching `request.signal`. The existing warning tests still hold: the message continues to include both `request.signal` and `--unstable-no-legacy-abort`. Refs #28850, #29111, #34397.
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Adds a dedicated reference page documenting the legacy
request.signalabort behavior in
Deno.serve: why it fires on successful responsestoday, why that breaks Node-style HTTP proxies (http-proxy,
http-proxy-middleware / Vite), and what the corrected behavior under
--unstable-no-legacy-abortlooks like.The most common reason people reach for the legacy abort is to know when
a response has been fully delivered. The page documents the intended
replacement, the
completedpromise onServeHandlerInfo(the handler'ssecond argument), which resolves once the response (including a streaming
body) is sent and rejects if delivery fails partway.
The page is intentionally kept out of the sidebar. It is reachable only
from the
--unstable-no-legacy-abortentry on the unstable flagsreference and from the
docs.deno.com/go/unstable-no-legacy-abortshortlink (added to
go.json). A companion deno PR points the runtimedeprecation warning at that short link.
Refs denoland/deno#28850, denoland/deno#29111, denoland/deno#34397.