react-hook-form

name: react-hook-form description: React Hook Form performance optimization for client-side form validation using useForm, useWatch, useController, useFieldArray, and the v7.55+ subscribe() API. This skill should be used when building client-side controlled forms with React Hook Form library. This skill does NOT cover React 19 Server Actions, useActionState, or server-side form handling (use react-19 skill for those).

React Hook Form Best Practices by Community

Comprehensive performance optimization guide for React Hook Form applications. Contains 45 rules across 8 categories, prioritized by impact to guide form development, automated refactoring, and code generation.

When to Apply

Reference these guidelines when:

• Writing new forms with React Hook Form
• Configuring useForm options (mode, defaultValues, validation)
• Subscribing to form values with watch / useWatch / subscribe
• Integrating controlled UI components (MUI, shadcn, Ant Design)
• Managing dynamic field arrays with useFieldArray
• Handling async submit, server errors, and submit lifecycle state
• Reviewing forms for performance issues

When NOT to Use This Skill

• React 19 Server Actions / useActionState — use the react-19 skill instead
• Deeply nested, fully type-safe forms — TanStack Form may be a better fit for forms with complex nested schemas; this skill assumes you've already chosen RHF
• Single-input or trivial forms — uncontrolled <form> + FormData is often simpler than pulling in any library

Rule Categories by Priority

Quick Reference

1. Form Configuration (CRITICAL)

• formcfg-validation-mode - Use onSubmit mode for optimal performance
• formcfg-revalidate-mode - Consider reValidateMode for expensive validation
• formcfg-default-values - Always provide defaultValues for form initialization
• formcfg-async-default-values - Use async defaultValues for server data
• formcfg-should-unregister - Enable shouldUnregister for dynamic form memory efficiency
• formcfg-useeffect-dependency - Avoid useForm return object in useEffect dependencies
• formcfg-disabled-prop - Understand that register's disabled prop clears the value

2. Field Subscription (CRITICAL)

• sub-usewatch-over-watch - Use useWatch instead of watch for isolated re-renders
• sub-watch-specific-fields - Watch specific fields instead of entire form
• sub-subscribe-outside-react - Use subscribe() for non-UI side-effects (analytics, autosave)
• sub-usewatch-with-getvalues - Combine useWatch with getValues for timing safety
• sub-deep-subscription - Subscribe deep in component tree where data is needed
• sub-avoid-watch-in-render - Avoid calling watch() in render for one-time reads
• sub-usewatch-default-value - Provide defaultValue to useWatch for initial render
• sub-useformcontext-sparingly - Use useFormContext sparingly for deep nesting

3. Controlled Components (HIGH)

• ctrl-usecontroller-isolation - Isolate controlled inputs in dedicated child components
• ctrl-avoid-double-registration - Avoid double registration with useController
• ctrl-controller-field-props - Wire Controller field props correctly for UI libraries
• ctrl-single-usecontroller-per-component - Use single useController per component
• ctrl-local-state-combination - Combine local state with useController for UI-only state

4. Validation Patterns (HIGH)

• valid-resolver-caching - Define schema outside component for resolver caching
• valid-server-errors - Surface server errors via setError('root.serverError', ...)
• valid-dynamic-schema-factory - Use schema factory for dynamic validation
• valid-error-message-strategy - Access errors via optional chaining or lodash get
• valid-inline-vs-resolver - Prefer resolver over inline validation for complex rules
• valid-delay-error - Use delayError to debounce rapid error display
• valid-native-validation - Consider native validation for simple forms

5. Field Arrays (MEDIUM-HIGH)

• array-use-field-id-as-key - Use field.id as key in useFieldArray maps
• array-complete-default-objects - Provide complete default objects for field array operations
• array-separate-crud-operations - Separate sequential field array operations
• array-unique-fieldarray-per-name - Use single useFieldArray instance per field name
• array-virtualization-formprovider - Use FormProvider for virtualized field arrays

6. State Management (MEDIUM)

• formstate-async-submit-lifecycle - Wrap async submit handlers in try/catch and reset on isSubmitSuccessful
• formstate-destructure-formstate - Destructure formState properties before render
• formstate-useformstate-isolation - Use useFormState for isolated state subscriptions
• formstate-getfieldstate-for-single-field - Use getFieldState for single field state access
• formstate-subscribe-to-specific-fields - Subscribe to specific field names in useFormState
• formstate-avoid-isvalid-with-onsubmit - Avoid isValid with onSubmit mode for button state

7. Integration Patterns (MEDIUM)

• integ-shadcn-form-import - Verify shadcn Form component import source
• integ-shadcn-select-wiring - Wire shadcn Select with onValueChange instead of spread
• integ-mui-controller-pattern - Use Controller for Material-UI components
• integ-value-transform - Transform values at Controller level for type coercion

8. Advanced Patterns (LOW)

• adv-formprovider-memo - Wrap FormProvider children with React.memo
• adv-devtools-performance - Disable DevTools in production and during performance testing
• adv-testing-wrapper - Create test wrapper with QueryClient and AuthProvider

How to Use

Read individual reference files for detailed explanations and code examples:

• Section definitions - Category structure and impact levels
• Rule template - Template for adding new rules
• Reference files: references/{prefix}-{slug}.md

Related Skills

• For schema validation with Zod resolver, see zod skill
• For React 19 server actions, see react-19 skill
• For UI/UX form design, see frontend-design skill

Full Compiled Document

For the complete guide with all rules expanded: AGENTS.md