regex - Regular Expression to reformat a US phone number in Javascript

Question

I'm looking to reformat (replace, not validate - there are many references for validating) a phone number for display in Javascript. Here's an example of some of the data:

• 123 4567890
• (123) 456-7890
• (123)456-7890
• 123 456 7890
• 123.456.7890
• (blank/null)
• 1234567890

Is there an easy way to use a regular expression to do this? I'm looking for the best way to do this. Is there a better way?

I want to reformat the number to the following: (123) 456-7890

Answer 1

Assuming you want the format "(123) 456-7890":

function formatPhoneNumber(phoneNumberString) {
  var cleaned = ('' + phoneNumberString).replace(/D/g, '');
  var match = cleaned.match(/^(d{3})(d{3})(d{4})$/);
  if (match) {
    return '(' + match[1] + ') ' + match[2] + '-' + match[3];
  }
  return null;
}

Here's a version that allows the optional +1 international code:

function formatPhoneNumber(phoneNumberString) {
  var cleaned = ('' + phoneNumberString).replace(/D/g, '');
  var match = cleaned.match(/^(1|)?(d{3})(d{3})(d{4})$/);
  if (match) {
    var intlCode = (match[1] ? '+1 ' : '');
    return [intlCode, '(', match[2], ') ', match[3], '-', match[4]].join('');
  }
  return null;
}
formatPhoneNumber('+12345678900') // => "+1 (234) 567-8900"
formatPhoneNumber('2345678900')   // => "(234) 567-8900"