title: Not allow url in textarea value
body: <p>I have a contact form in which I have a textarea.
  I'd like to not allow to submit if the textarea value contains a url.</p>
  
  <p>I tried with html pattern but not effects
  for example : <code>&lt;textarea pattern="[^http:|https]"</code> </p>
  
  <p>Any ideas ?</p>
  
  <p>thanks</p>