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Rules reference

react-doctor/lang

Use a valid BCP-47 language tag on `<html lang>` (e.g. `en` / `en-US`).

Validation prompt

Use this to decide whether a fired diagnostic is real or a false positive.

Fires on a <html> element (including <HTML> or a component resolved to "html" via jsx-a11y polymorphic/components settings) whose lang prop is invalid: explicitly lang={undefined} or lang={null}, or a static string whose value fails BCP-47 validation — the primary subtag must match a known ISO-639 tag and every -/_-separated subtag must be alphanumeric. A dynamic value like lang={foo} is NOT flagged. False positive: the primary-tag set is a partial, hand-maintained ISO-639 list, so a genuinely valid but uncommon or newer language tag absent from that set is wrongly reported.

Fix prompt

Use this once validation confirms the diagnostic is real.

Set lang to a valid BCP-47 / IANA language tag — <html lang="en"> or a region-qualified <html lang="en-US">, script-qualified <html lang="zh-Hans"> as needed. Never leave it as lang={undefined} or lang={null}; if the value is computed, ensure it always resolves to a real tag. If the linter rejects a tag you've confirmed is valid (e.g. a rare ISO-639 code), it's a known gap in the rule's partial tag list — suppress that line with a justifying comment. See https://oxc.rs/docs/guide/usage/linter/rules/jsx_a11y/lang

More Accessibility rules from the rules reference: