Phone Number Validation RegEx Pattern

phoneNumberIsValid.js

/*
Valid phone number patterns:
    01611234567
    0161 123 4567
    (0161) 123 4567
    0161-123-4567
    +44 161 123 4567
    +441611234567
    +44(0)161234567
    00 44 161 1234567
    (011) 44 161 234567
    0161-158-5587
    0161 123 4567 ext. 123
    01611234567x123
    +44161234567x123
    +44 (0) 161 1234567 ext 123
*/

function _isValidPhone(toAssess) {
  var pattern = i = /^\(?(?:(?:0(?:0|11)\)?[\s-]?\(?|\+)44\)?[\s-]?\(?(?:0\)?[\s-]?\(?)?|0)(?:\d{2}\)?[\s-]?\d{4}[\s-]?\d{4}|\d{3}\)?[\s-]?\d{3}[\s-]?\d{3,4}|\d{4}\)?[\s-]?(?:\d{5}|\d{3}[\s-]?\d{3})|\d{5}\)?[\s-]?\d{4,5}|8(?:00[\s-]?11[\s-]?11|45[\s-]?46[\s-]?4\d))(?:(?:[\s-]?(?:x|ext\.?\s?|\#)\d+)?)$/;
  return pattern.test(toAssess);
}