title: Find the regex used by HTML5 forms for validation
body: <p>Some HTML5 input elements accept the <code>pattern</code> attribute, which is a regex for form validation. Some other HTML5 input elements, such as, <code>input type=email</code> does the validation automatically.</p>
  
  <p>Now it seems that the way validation is handled is different accross browsers. Given a specific browser, say Chrome, is it possible to programmatically extract the regex used for validation? Or maybe there is documentation out there?</p>