What is Custom Hook pattern? Custom Hook pattern क्या है?

// Custom Hook - reusable logic
function useForm(initialValues, onSubmit) {
  const [values, setValues] = React.useState(initialValues);
  
  const handleChange = (e) => {
    setValues({ ...values, [e.target.name]: e.target.value });
  };
  
  const handleSubmit = (e) => {
    e.preventDefault();
    onSubmit(values);
  };
  
  return { values, handleChange, handleSubmit };
}

// Usage
function LoginForm() {
  const form = useForm({ email: '', password: '' }, (values) => {
    console.log('Login:', values);
  });
  
  return <form onSubmit={form.handleSubmit}>...</form>;
}