We plan to deploy the feature as an enabled-by-default base::Feature, primarily to act as an emergency shutoff valve rather than going through a formal feature rollout. This approach aligns with the consensus-based standards section, which doesn’t call for a gradual rollout, and given the low risk, we believe a full rollout process isn’t necessary.
That said, we’re calling this out here to give an opportunity to raise any concerns about deploying it in this way. On Monday, May 19, 2025 at 1:25:59 PM UTC-7 Issack John wrote: > Contact emails > issac...@microsoft.com, dan...@microsoft.com > > Explainer > None > > Specification > https://mimesniff.spec.whatwg.org/#json-mime-type > > Summary > Chromium now recognizes all valid JSON MIME types as defined by the WHATWG > mimesniff specification. This includes any MIME type whose subtype ends > with “+json”, in addition to the traditional application/json and > text/json. This change ensures that web APIs and features relying on JSON > detection behave consistently with the web platform standard and other > browsers. A key motivation for this change is to fix JSON module import > behavior, where previously valid JSON MIME types like text/html+json and > image/svg+json would fail to load as modules. Draft CL: > https://chromium-review.googlesource.com/c/chromium/src/+/6525687 Related > Issues: https://github.com/whatwg/mimesniff/issues/112. The consensus was > to retain the broad definition of JSON MIME types—including all */*+json. > > > Blink component > Blink>Network > <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ENetwork%22> > > Search tags > json <https://chromestatus.com/features#tags:json>, mime > <https://chromestatus.com/features#tags:mime>, sniffing > <https://chromestatus.com/features#tags:sniffing>, spec-compliance > <https://chromestatus.com/features#tags:spec-compliance>, interoperability > <https://chromestatus.com/features#tags:interoperability> > > TAG review > None; this is a small change to match an existing spec and behavior of > other browsers. > > TAG review status > Not applicable > > Risks > > > Interoperability and Compatibility > Interoperability risk is low. This change brings Chromium into alignment > with the WHATWG MIME Sniffing Standard §4.6, which defines a JSON MIME type > as any MIME type whose subtype ends with +json (e.g., text/html+json, > image/svg+json), or is exactly application/json or text/json. Firefox and > Safari already match this behavior, and the change improves > interoperability for web developers. > https://wpt.fyi/results/html/semantics/scripting-1/the-script-element/json-module/valid-content-type.html > > A specific compatibility consequence is that JSON module imports (both > static and dynamic) of files with */*+json MIME types would previously have > produced an error but will now succeed. This seems low risk. > > > *Gecko*: Shipped/Shipping > > *WebKit*: Shipped/Shipping > > *Web developers*: No signals > > *Other signals*: > > Ergonomics > None expected > > > WebView application risks > *Does this intent deprecate or change behavior of existing APIs, such that > it has potentially high risk for Android WebView-based applications?* > None > > > Debuggability > None > > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)? > Yes > > Is this feature fully tested by web-platform-tests > <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> > ? > Yes > Test: > https://wpt.fyi/results/html/semantics/scripting-1/the-script-element/json-module/valid-content-type.html > > > Flag name on about://flags > None > > Finch feature name > SpecCompliantJsonMimeTypes > > Rollout plan > Will ship enabled for all users > > Requires code in //chrome? > False > > Estimated milestones > Shipping on desktop > 138 > Shipping on Android > 138 > Shipping on WebView > 138 > > > Anticipated spec changes > *Open questions about a feature may be a source of future web compat or > interop issues. Please list open issues (e.g. links to known github issues > in the project for the feature specification) whose resolution may > introduce web compat/interop risk (e.g., changing to naming or structure of > the API in a non-backward-compatible way).* > None > > Link to entry on the Chrome Platform Status > https://chromestatus.com/feature/5470594816278528?gate=6275763980206080 > > This intent message was generated by Chrome Platform Status > <https://chromestatus.com/>. > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/52cec510-3355-4452-b961-b9f5fe1cb323n%40chromium.org.
