FCC - JavaScript Algorithms and Data Structures Projects: Telephone Number Validator

index.js

function telephoneCheck(phoneNumber = "") {
  const hasValidLength = isValidTelephoneLength(phoneNumber);

  let copyPhoneNumber = phoneNumber;

  if (!hasValidLength) return false;

  if (hasCountryCode(copyPhoneNumber)) {
    if (!hasValidCountryCode(copyPhoneNumber)) return false;
    copyPhoneNumber = cleanWhitespaceAtStart(
      copyPhoneNumber.substring(1, copyPhoneNumber.length)
    );
  } else {
    // check if its straight 10 length
    // eg: 5555555555
    if (copyPhoneNumber.length === 10) return true;
  }

  if (containValidPrefixNumberParentheses(copyPhoneNumber)) {
    return isValidPhoneNumberValidAfterPrefixNumber(copyPhoneNumber);
  }
  return (
    containValidPhoneNumberSeparatorAndParts(copyPhoneNumber, "-") ||
    containValidPhoneNumberSeparatorAndParts(copyPhoneNumber, " ")
  );
}

function getPhoneNumberLength(phoneNumber = "") {
  const numberRegex = /\d+/g;
  return phoneNumber.match(numberRegex).join("").length;
}

function isValidTelephoneLength(phoneNumber = "") {
  const acceptedTelephoneLengths = [10, 11];

  const phoneNumberLength = getPhoneNumberLength(phoneNumber);
  return acceptedTelephoneLengths.indexOf(phoneNumberLength) > -1;
}

function hasCountryCode(phoneNumber = "") {
  return getPhoneNumberLength(phoneNumber) === 11 ? true : false;
}

function hasValidCountryCode(phoneNumber = "") {
  const acceptedCountryCodes = [1];
  const firstNumber = parseInt(phoneNumber[0]);
  return acceptedCountryCodes.indexOf(firstNumber) > -1;
}

// A valid parentheses appears for the first 3 digits of the phoneNumber

// !!! Note that this may difer if the phoneNumber has a country code !!!
function containValidPrefixNumberParentheses(phoneNumber = "") {
  const matchCapture = phoneNumber.substring(0, 5);
  // Check if the first and last is ( or )
  if (
    matchCapture[0] === "(" &&
    matchCapture[matchCapture.length - 1] === ")"
  ) {
    return true;
  }
  return false;
}

function isValidPhoneNumberValidAfterPrefixNumber(phoneNumber = "") {
  // eg: (555)555-5555
  // we get the "555-5555" and check if their separator is valid '-'

  // There should only one group of ( )
  // example of invalid: (555)5(55?)-5555
  const [parenthesesIndexA, parenthesesIndexB] = [
    phoneNumber.indexOf(")"),
    phoneNumber.lastIndexOf(")")
  ];
  if (parenthesesIndexA !== parenthesesIndexB) return false;
  const indexAfterLastParentheses = phoneNumber.lastIndexOf(")");
  const telephoneNumberWithoutPrefix = phoneNumber.substring(
    indexAfterLastParentheses + 1,
    phoneNumber.length
  );

  return telephoneNumberWithoutPrefix.split("-").length === 2;
}

function containValidPhoneNumberSeparatorAndParts(
  phoneNumber = "",
  separator = "-"
) {
  const phoneNumberParts = phoneNumber.split(separator);
  phoneNumber;
  if (phoneNumberParts.length === 3) {
    // first part length = 3; second part length = 3; third part length = 4
    phoneNumberParts;
    return (
      phoneNumberParts[0].length === 3 &&
      phoneNumberParts[1].length === 3 &&
      phoneNumberParts[2].length === 4
    );
  }
  return false;
}

function cleanWhitespaceAtStart(phoneNumber = "") {
  return phoneNumber.replace(/^\s+(?=\d)/g, "").replace(/^\s+(?=\W)/g, "");
}