Normalizes any Sri Lankan phone number string into a clean 10-digit national number (e.g., '0771234567').
Phone number in any common format.
The national form with a leading 0 and no separators, or '' if the input contains other characters.
''
normalizePhoneNumber('+94 77 123 4567'); // '0771234567'normalizePhoneNumber('(011) 234-5678'); // '0112345678' Copy
normalizePhoneNumber('+94 77 123 4567'); // '0771234567'normalizePhoneNumber('(011) 234-5678'); // '0112345678'
Normalizes any Sri Lankan phone number string into a clean 10-digit national number (e.g., '0771234567').