title: javascript regex validation
body: <p>Is there any way to find which input character fails the <strong>regex pattern</strong>.</p>
  
  <p>For ex: consider [A-Za-z\s.&amp;] is only allowable but the user enter like "test/string" where '/' invalidates input. <em>How to find who fails regex <strong>(our case '/')</em></strong></p>