# `react-hooks-js/set-state-in-render`

Validates against setting state during render, which can trigger additional renders and potential infinite render loops

- **Status:** Active
- **Category:** React Compiler
- **Assessment:** Evidence-required risk
- **Required evidence:** source code
- **Default severity:** error
- **Scope:** All supported frameworks
- **Active when:** eslint-plugin-react-hooks v6+ installed AND React Compiler detected in project
- **Priority:** 87 (P0)
- **Source:** eslint-plugin-react-hooks
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://react.dev/reference/eslint-plugin-react-hooks/lints/set-state-in-render)

## Validation prompt

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

Fires on UNCONDITIONAL setState during render: guaranteed infinite loop. The conditional sync-state-to-prop pattern (if (items !== prevItems) { setPrevItems(items); setSelection(null); }) is explicitly allowed and is the documented escape hatch.

Suppress when: rare; bare setState in the component body is almost always a real bug.

## 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.

## Fix prompt

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

Move the setState into an event handler (onClick, onChange, onSubmit) or into useEffect if it must run after commit. To synchronize state with a prop change across renders, use the gated pattern above: store the previous prop in state and only call setState when it differs. For clamping or derived values, derive during render instead of mirroring into state. See https://react.dev/reference/eslint-plugin-react-hooks/lints/set-state-in-render

## 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-hooks-js/set-state-in-render` diagnostic in the current repository.

Required change:
- Move the setState into an event handler (onClick, onChange, onSubmit) or into useEffect if it must run after commit. To synchronize state with a prop change across renders, use the gated pattern above: store the previous prop in state and only call setState when it differs. For clamping or derived values, derive during render instead of mirroring into state. See https://react.dev/reference/eslint-plugin-react-hooks/lints/set-state-in-render

Validation before editing:
Fires on UNCONDITIONAL setState during render: guaranteed infinite loop. The conditional sync-state-to-prop pattern (if (items !== prevItems) { setPrevItems(items); setSelection(null); }) is explicitly allowed and is the documented escape hatch.

Suppress when: rare; bare setState in the component body is almost always a real bug.

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.
````