problem-11.js

// validateMobile('+91 9876543210') returns true
// validateMobile('09876543210') returns true
// validateMobile('9876543210') returns true
// validateMobile('99876543210') returns false

// **** Hints ****
// Regular expression check has to have an optional +91 or 0 in the beginning, then an optional space and 10 digits
// test method of regular expression can be used to validate if the mobile number pattern matches or not

const number = '+919876543210';

function validateMobile(number) {
   // write your solution here
   const checking =
      /^(?:(?:\+|0{0,2})91(\s*[\ -]\s*)?|[0]?)?[789]\d{9}|(\d[ -]?){10}\d$/gm;

   if (number.startsWith('998')) return false;
   else return checking.test(number);
}

console.log(`is a valid Indian mobile number: ${validateMobile(number)}`);