ほぼJSなしで完璧なReactフォームをつくるimport { ChangeEvent, FormEvent } from "react"; export default function Form() { const showError = (message: string) => (e: FormEvent<HTMLInputElement>) => { if (e.currentTarget.validity.valueMissing) { e.currentTarget.setCustomValidity(message); } else if ( e.currentTarget.validity.patternMismatch && e.currentTarget.name === "postcode" ) { e.currentTarget.setCustomValidity("郵便番号正しく入力してね"); } else
