Formatting the phone number

Answer 1

const formatPhoneNumber = (phoneNumber) => {
  // convert the raw number to (xxx) xxx-xxx format
  const x = phoneNumber && phoneNumber.replace(/\D/g, '').match(/(\d{0,3})(\d{0,3})(\d{0,4})/);
  return !x[2] ? x[1] : `(${x[1]}) ${x[2]}${x[3] ? `-${x[3]}` : ''}`;
};

console.log(formatPhoneNumber("1111111111"));

Answer 2

phone = "0123456789"
formated_phone = "("+phone.substring(0,3)+")"+phone.substring(3,6)+"-"+phone.substring(6,11)

Answer 3

I would prefer to use replace and regexp (less code, more features).

         var phone = "0123456789";
         phone.replace(/(\d{3})(\d{3})(\d{4})/,"($1)$2-$3"); // (012)345-6789

Reference: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/replace