# `react-doctor/no-high-complexity-react-function`

A React component or custom hook exceeds the cyclomatic or cognitive complexity threshold

- **Status:** Active
- **Category:** Maintainability
- **Assessment:** Evidence-required risk
- **Required evidence:** source code, repository context
- **Default configuration:** Enabled
- **Default severity:** warn
- **Scope:** All supported frameworks
- **Active when:** React components and custom hooks
- **Tags:** test-noise, react-jsx-only
- **Priority:** Unranked; sorts as P3
- **Source:** oxlint-plugin-react-doctor
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://www.react.doctor/docs/overview/react-maintainability)

## Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

This rule checks function declarations, function expressions, and arrow functions identified as React components or custom hooks. It reports when cyclomatic or cognitive complexity exceeds 15 and includes both measurements plus maximum nesting depth. Nested callback control flow is not charged to the owning React function. Confirm the reported branches belong to the component or hook and make its React behavior difficult to follow. Reject ordinary JavaScript functions, functions without React component evidence, and metrics caused only by nested callbacks.

## Evidence boundary

The diagnostic proves only that the detector's modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.

Default severity is registry metadata. Use the occurrence's JSON severity after repository configuration when ordering real findings.

Record one outcome:

- **Confirmed failure:** The required evidence establishes the violation.
- **Rejected:** A documented exception or false-positive predicate applies.
- **Needs evidence:** Named evidence can still be collected.
- **Unavailable:** Required evidence cannot be collected in this run.
- **Waived with evidence:** An authorized, scoped exception applies to an established failure.
- **Observation:** The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

## Review a candidate correction

Apply this candidate correction only after the required evidence confirms the risk.

### Reported pattern

```tsx
const AccountPanel = ({ account }: Props) => {
  if (account.isLoading) return <Spinner />;
  if (account.isLocked) return <LockedNotice />;
  if (account.hasError) return <ErrorNotice />;
  if (account.needsReview) return <ReviewNotice />;
  if (account.isExpired) return <ExpiredNotice />;
  if (account.isSuspended) return <SuspendedNotice />;
  if (account.isReadonly) return <ReadonlyNotice />;
  if (account.needsUpgrade) return <UpgradeNotice />;
  if (account.isOffline) return <OfflineNotice />;
  if (account.isSyncing) return <SyncingNotice />;
  if (account.needsConsent) return <ConsentNotice />;
  if (account.isMigrating) return <MigrationNotice />;
  if (account.hasConflict) return <ConflictNotice />;
  if (account.isDeleting) return <DeletingNotice />;
  if (account.isArchived) return <ArchivedNotice />;
  return <AccountDetails account={account} />;
};
```

### Candidate corrected pattern

```tsx
const AccountPanel = ({ account }: Props) => {
  const status = getAccountStatus(account);
  return <AccountStatus status={status} account={account} />;
};
```

## Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

Extract independent render branches into focused components and move cohesive state or effect logic into custom hooks. Keep state ownership, render order, hook order, event behavior, and component interfaces intact. Do not split a function only to lower the number when the resulting indirection makes the behavior harder to follow. Re-run React Doctor and the affected component tests after refactoring.

## Repository-wide copy prompt

Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.

````text
Fix every confirmed `react-doctor/no-high-complexity-react-function` diagnostic in the current repository.

Required change:
- Extract independent render branches into focused components and move cohesive state or effect logic into custom hooks. Keep state ownership, render order, hook order, event behavior, and component interfaces intact. Do not split a function only to lower the number when the resulting indirection makes the behavior harder to follow. Re-run React Doctor and the affected component tests after refactoring.

Validation before editing:
This rule checks function declarations, function expressions, and arrow functions identified as React components or custom hooks. It reports when cyclomatic or cognitive complexity exceeds 15 and includes both measurements plus maximum nesting depth. Nested callback control flow is not charged to the owning React function. Confirm the reported branches belong to the component or hook and make its React behavior difficult to follow. Reject ordinary JavaScript functions, functions without React component evidence, and metrics caused only by nested callbacks.

Constraints:
- Confirm every occurrence independently.
- Make the smallest change that addresses the root cause.
- Preserve unrelated behavior, interfaces, content, and semantics.
- Reuse existing project conventions and components.
- Do not suppress the rule merely to clear the report.

Assessment:
- Record detector evidence, applicability, missing evidence, and one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.

Verification:
- Run focused tests and every repository-mandated check.
- Run React Doctor and confirm the diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report checks that were not run instead of claiming they passed.
````