Real-World Validation PatternsLesson 5.3

Phone number validation regex for multiple formats

US phone formats, international format, optional parts, character class for separators, normalization after match, test suite approach

Phone Numbers Come in Too Many Formats

Validate the structure, then normalize to a canonical form. Do not try to match all formats in one rigid pattern.

const phoneRe = /^\(?\d{3}\)?[\s.\-]?\d{3}[\s.\-]?\d{4}$/;

phoneRe.test('4155550000')     // true
phoneRe.test('415-555-0000')   // true

function normalizePhone(input) {
  if (!phoneRe.test(input)) return null;
  return input.replace(/\D/g, '');
}