React Router Code Review
Quick Reference
| Issue Type | Reference |
|---|---|
| useEffect for data, missing loaders, params | references/data-loading.md |
| Form vs useFetcher, action patterns | references/mutations.md |
| Missing error boundaries, errorElement | references/error-handling.md |
| navigate() vs Link, pending states | references/navigation.md |
Review Checklist
- Data loaded via
loadernotuseEffect - Route params accessed type-safely with validation
- Using
defer()for parallel data fetching when appropriate - Mutations use
<Form>oruseFetchernot manual fetch - Actions handle both success and error cases
- Error boundaries with
errorElementon routes - Using
isRouteErrorResponse()to check error types - Navigation uses
<Link>overnavigate()where possible - Pending states shown via
useNavigation()orfetcher.state - No navigation in render (only in effects or handlers)
Valid Patterns (Do NOT Flag)
These patterns are correct React Router usage - do not report as issues:
- useEffect for client-only data - Loaders run server-side; localStorage, window dimensions, and browser APIs must use useEffect
- navigate() in event handlers - Link is for declarative navigation; navigate() is correct for imperative navigation in callbacks/handlers
- Type annotation on loader data -
useLoaderData<typeof loader>()is a type annotation, not a type assertion - Empty errorElement at route level - Route may intentionally rely on parent error boundary
- Form without action prop - Posts to current URL by convention; explicit action is optional
- loader returning null - Valid when data may not exist; null is a legitimate loader return value
- Using fetcher.data without checking fetcher.state - May be intentional when stale data is acceptable during revalidation
Context-Sensitive Rules
Only flag these issues when the specific context applies:
| Issue | Flag ONLY IF |
|---|---|
| Missing loader | Data is available server-side (not client-only) |
| useEffect for data fetching | Data is NOT client-only (localStorage, browser APIs, window size) |
| Missing errorElement | No parent route in the hierarchy has an error boundary |
| navigate() instead of Link | Navigation is NOT triggered by an event handler or conditional logic |
When to Load References
- Reviewing data fetching code → data-loading.md
- Reviewing forms or mutations → mutations.md
- Reviewing error handling → error-handling.md
- Reviewing navigation logic → navigation.md
Review Questions
- Is data loaded in loaders instead of effects?
- Are mutations using Form/action patterns?
- Are there error boundaries at appropriate route levels?
- Is navigation declarative with Link components?
- Are pending states properly handled?
Before Submitting Findings
Load and follow review-verification-protocol before reporting any issue.