# `react-hooks-js/void-use-memo`

Validates that useMemos always return a value and that the result of the useMemo is used by the component/hook. See [`useMemo()` docs](https://react.dev/reference/react/useMemo) for more information.

- **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:** 33 (P3)
- **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)

## Validation prompt

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

Fires when a useMemo's return value is never consumed: not assigned, not destructured, not returned from the surrounding component/hook. The cached value is computed and immediately discarded, so the hook is effectively a side-effect call dressed up as memoization.

Suppress when: rare; an unused memo is almost always a mistake.

## 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.

Assign the result and reference it downstream (const sorted = useMemo(() => [...items].sort(), [items]); return <List items={sorted} />). If you do not need the value, you do not need the memo: delete it and either move the work to useEffect for synchronization or to an event handler for user-triggered side effects. See https://react.dev/reference/eslint-plugin-react-hooks

## 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/void-use-memo` diagnostic in the current repository.

Required change:
- Assign the result and reference it downstream (const sorted = useMemo(() => [...items].sort(), [items]); return <List items={sorted} />). If you do not need the value, you do not need the memo: delete it and either move the work to useEffect for synchronization or to an event handler for user-triggered side effects. See https://react.dev/reference/eslint-plugin-react-hooks

Validation before editing:
Fires when a useMemo's return value is never consumed: not assigned, not destructured, not returned from the surrounding component/hook. The cached value is computed and immediately discarded, so the hook is effectively a side-effect call dressed up as memoization.

Suppress when: rare; an unused memo is almost always a mistake.

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.
````