title: jquery.validate - button disabled until valid email
body: <p>I am using <a href="https://jqueryvalidation.org/" rel="nofollow">https://jqueryvalidation.org/</a> to validate my form on the frontend. The basic "if field is empty - validate" works OK.</p>
  
  <p>But I'd like to the submit button to be initially disabled until a valid email address has been entered.   I'd like the button to become enabled as soon as the field becomes valid (on keypress).</p>
  
  <p>So basically I just need to remove the 'btn-disabled' class once its valid.  </p>
  
  <p>I'm struggling with the jQuery to add this function/method. Would be grateful if someone can help out. </p>
  
  <p>Heres a slightly simplifed version:  <a href="http://codepen.io/dagford/pen/kXJpEZ" rel="nofollow">http://codepen.io/dagford/pen/kXJpEZ</a></p>
  
  <pre><code>$(document).ready(function(){
  
      $("#reset-form").validate({
          rules: {
              emailaddress: {
                  required: true,
                  email: true
              }
  
          },
          messages: {
              email: "Please enter a valid email address"
          }
  
      }); 
  
  });
  </code></pre>