The provided function `formatPhoneNumber` takes a phone number as input and returns a formatted version of that phone number.

formatPhoneNumberHelper.ts

export const formatPhoneNumberHelper = (number: string): string => {
  const cleanedNumber: string = String(number).replace(/\D/g, "");

  // Check if the number has at least 10 digits
  if (cleanedNumber.length < 10) {
    return number;
  }

  // Extract the DDI (the first digits, can be 2 or 3)
  const DDI: string = cleanedNumber.slice(
    0,
    2 + (cleanedNumber.length > 13 ? 1 : 0)
  );

  // Extract the DDD (the next digits)
  const DDD: string = cleanedNumber.slice(DDI.length, DDI.length + 2);

  // Extract the remaining phone number
  const phoneNumber: string = cleanedNumber.slice(DDI.length + DDD.length);

  let phoneNumberFormatted = phoneNumber;

  // Format phone number to return "9 9999-9999"
  if (phoneNumber.length === 9) {
    // Split the number into parts
    const part1 = phoneNumber.slice(0, 1);
    const firstPartPhoneNumber = phoneNumber.slice(1, 5);
    const secondPartPhoneNumber = phoneNumber.slice(5);

    // Concatenate the formatted parts
    phoneNumberFormatted = `${part1} ${firstPartPhoneNumber}-${secondPartPhoneNumber}`;
  }

  // Format the number as desired
  const formattedNumber: string = `+${DDI} (${DDD}) ${phoneNumberFormatted}`;

  return formattedNumber;
};