Change <button type="button" to <button type="submit". Remove the onClick. Instead do <form className="commentForm" onSubmit={onFormSubmit}>. This should catch clicking the button and pressing the return key.
const onFormSubmit = e => { e.preventDefault(); // send state to server with e.g. `window.fetch` } ... <form onSubmit={onFormSubmit}> ... <button type="submit">Submit</button> </form>
Full example without any silly form libraries:
function LoginForm() { const [email, setEmail] = useState('') const [password, setPassword] = useState('') const [submitting, setSubmitting] = useState(false) const [formError, setFormError] = useState('') const onFormSubmit = async (e: React.FormEvent<HTMLFormElement>) => { try { e.preventDefault(); setFormError('') setSubmitting(true) await fetch(/*POST email + password*/) } catch (err: any) { console.error(err) setFormError(err.toString()) } finally { setSubmitting(false) } } return ( <form onSubmit={onFormSubmit}> <input type="email" autoComplete="email" value={email} onChange={e => setEmail(e.currentTarget.value)} required /> <input type="password" autoComplete="current-password" value={password} onChange={e => setPassword(e.currentTarget.value)} required /> {Boolean(formError) && <div className="form-error">{formError}</div> } <button type="submit" disabled={submitting}>Login</button> </form> ) }
P.S. Remember that any buttons in your form which should not submit the form should explicitly have type="button".