var email = " hoge@hoge@example.com\n "
console.log(email);

email = email.trim();
console.log(email);
findA = email.indexOf("@");

var localpart = email.substring(0, findA);
console.log(localpart)
var domainpart = email.substring(findA+1, email.length);
console.log(domainpart)
// console.log(`local=${localpart}, dom=${domainpart}`);
console.log(email.matchAll)