react-doctor/hooks-no-nan-in-deps

Remove the literal NaN from the dependency array, or normalise it (Number.isNaN(x) ? 0 : x) before passing it in.

  • Category: State & Effects
  • Severity: warn
  • Source: oxlint-plugin-react-doctor
  • Framework: global
  • Enabled when: always

Validation prompt

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

Fires on a CallExpression whose callee is one of useEffect, useLayoutEffect, useInsertionEffect, useCallback, useMemo, or useImperativeHandle (matched by isHookCall, so React.useEffect-style member calls count too) when the dependency-array argument — index 1, or index 2 for useImperativeHandle(ref, factory, deps) — is an ArrayExpression containing an element that is either the bare Identifier NaN or the non-computed MemberExpression Number.NaN; it reports each such element separately. False positive boundary derived from the valid fixtures: it does NOT fire on useSignalEffect (Preact signals, single-arg auto-tracking API with no deps array — intentionally excluded), on normal dep arrays like [id, name], on empty [] deps, on a hook with the deps argument omitted entirely, or on non-hook calls such as createThing("foo", [NaN]). Note the rule only matches the static NaN and Number.NaN literal shapes; a dynamically computed NaN, such as a value that becomes NaN via Number(input), is not detected here, so a clean dep array that holds a normal identifier is correctly left alone even if that identifier could be NaN at runtime.

Fix prompt

Use this once validation confirms the diagnostic is real.

Delete the NaN (or Number.NaN) entry from the dependency array — it is almost always a leftover placeholder or the result of an unchecked coercion like Number(input) returning NaN. Because React compares deps with Object.is and Object.is(NaN, NaN) is true, a poisoned NaN makes the hook treat the dep as unchanged so it stops re-running on real changes, and any later transition between NaN and a real number can wedge dependency tracking. If the real value can become NaN at runtime, depend on a normalised version instead: const safe = Number.isNaN(x) ? 0 : x; useEffect(fn, [safe]). Never list a raw NaN literal in deps.