title: Forgiving JavaScript validation for US phone numbers and allowing extensions (jquery allowed)
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/123559/a-comprehensive-regex-for-phone-number-validation">A comprehensive regex for phone number validation</a>  </p>
  </blockquote>
  
  
  
  <p>Perhaps a forgiving JavaScript solution would only make sure that only valid characters are allowed. (digits, dashes, periods, letters for extension.</p>
  
  <p>Although loop seems best, is there a simple regular expression that checks for valid characters?</p>