react-hook-form

name	react-hook-form
description	React Hook Form — performant form management with uncontrolled inputs, validation, and field arrays.

react-hook-form

useForm & Register

• useForm({ defaultValues: { name: '' } }) — initialize form context.
• register('name', { required: true }) — spread into <input> for uncontrolled binding.
• register('email', { pattern: /^\S+@\S+$/ }) — inline validation rules.
• register('age', { valueAsNumber: true }) — automatic type coercion.

Validation

• Native rules: required, minLength, maxLength, min, max, pattern, validate.
• validate: (val) => val.length > 3 || 'too short' — custom sync/async validator.
• Schema validation: zodResolver(schema) / yupResolver(schema) from @hookform/resolvers.
• shouldUseNativeValidation: true — browser-native validation messages.

Errors & Form State

• formState.errors.name?.message — per-field error object from validation.
• formState.isDirty, isSubmitting, isValid, submitCount — reactive form state.
• trigger('email') — manually validate a single field.
• setError('name', { message: 'taken' }) — server-side validation errors.

useFieldArray

• useFieldArray({ control, name: 'items' }) — dynamic list of fields.
• fields.map((item, i) => <input key={item.id} {...register(items.${i}.value)} />).
• Methods: append, prepend, remove, insert, swap, move, replace.
• Each field needs unique id from fields array (not index as key).

Controller & Performance

• <Controller render={({ field }) => <Select {...field} />} name="country" control={control} />.
• Uncontrolled inputs = minimal re-renders; Controller for custom/third-party components.
• useWatch({ name: 'field' }) — subscribe to field changes without re-render.
• useFormContext() / <FormProvider> — shared form context for deeply nested components.