1import React from 'react';import { useForm } from 'react-hook-form'; function App() { const { register, handleSubmit, errors } = useForm(); // initialise the hook const onSubmit = (data) => { console.log(data); }; return ( <form onSubmit={handleSubmit(onSubmit)}> <input name="firstname" ref={register} /> {/* register an input */} <input name="lastname" ref={register({ required: true })} /> {errors.lastname && 'Last name is required.'} <input name="age" ref={register({ pattern: /\d+/ })} /> {errors.age && 'Please enter number for age.'} <input type="submit" /> </form> );}