title: Disable submit button if all three of three specific dropdown fields are empty
body: <p>There are four dropdowns in the form. One is optional. Of the other three, at least one has to be chosen. I have a script that I'm using on a form with one field, that disables submit until a selection is made. But I can't figure out and can't find how to adapt it to be disabled until at least one of three specific dropdowns has a selection made. Here's the current script:</p>
  
  <pre><code>jQuery(function($) {
      $('#ssbbcmodal-attribute').change(function() {
          var empty = false;
          $('#ssbbcmodal-attribute').each(function() {
              if ($(this).val() == null) {
                  empty = true;
              }
          });
          if (empty) {
              $('#ssbbcmodal-submit').attr('disabled', 'disabled');
          } else {
              $('#ssbbcmodal-submit').removeAttr('disabled');
          }
      });
  })()
  </code></pre>
  
  <p><strong>UPDATE 1</strong></p>
  
  <p>I might have thought of a way to do it. Will be back soon with update.</p>
  
  <p><strong>UPDATE 2</strong></p>
  
  <p>OK, my way to do it didn't work, probably because I'm guessing at this. Here's what I tried:</p>
  
  <pre><code>jQuery(function($) {
  var empty = false;
  
      $('#sseomodal-level').change(function() {
          var levelempty = false;
          $('#sseomodal-level').each(function() {
              if ($(this).val() == null) {
                  levelempty = true;
              }
          });
      });
      $('#sseomodal-username').change(function() {
          var userempty = false;
          $('#sseomodal-username').each(function() {
              if ($(this).val() == null) {
                  userempty = true;
              }
          });
      });
      $('#sseomodal-logged').change(function() {
          var loggedempty = false;
          $('#sseomodal-logged').each(function() {
              if ($(this).val() == null) {
                  loggedempty = true;
              }
          });
      });     
  
  if (levelempty === true &amp;&amp; userempty === true &amp;&amp; loggedempty === true)
      {empty = false}
   if (empty) {
              $('#sseomodal-submit').attr('disabled', 'disabled');
          } else {
              $('#sseomodal-submit').removeAttr('disabled');
          }
  })()
  </code></pre>
  
  <p>The disabled attribute is never removed with this, i.e., it doesn't work.</p>