title: Trouble with required fields and multi step form
body: <p>I have big trouble with a multi step form I did by myself using jquery (hide, and display divs)</p>
  
  <p>here is how it looks like</p>
  
  <p><img src="https://i.stack.imgur.com/LAIzh.png" alt="enter image description here"></p>
  
  <p>the trouble I have is for the fields that have the attribute "required". In fact All the form works fine, but the trouble is that it does not display the required until I click to the sublit button.</p>
  
  <p>And when we are to the final page and we do submit, it recall that some inputs are missings, here is below the message error in the console of chrome</p>
  
  <pre><code>An invalid form control with name='raison_sociale' is not focusable. index.php?p=demande-devis&amp;categorie=professionnel&amp;type=menuiserie:1
  An invalid form control with name='nom' is not focusable. index.php?p=demande-devis&amp;categorie=professionnel&amp;type=menuiserie:1
  An invalid form control with name='siret' is not focusable. index.php?p=demande-devis&amp;categorie=professionnel&amp;type=menuiserie:1
  An invalid form control with name='prenom' is not focusable. index.php?p=demande-devis&amp;categorie=professionnel&amp;type=menuiserie:1
  An invalid form control with name='no_tva' is not focusable. 
  </code></pre>
  
  <p>I don't know how to check the required attributes without validating the form, but just before changing the step of my form...</p>
  
  <p>anykind of help will be much appreciated.</p>